Subscribe to RSS
DOI: 10.1055/s-0029-1216823
Synthesis of 2-Methylindoline- and 2-Methyl-1,2,3,4-tetrahydroquinoline-Derived Phosphoramidites and Their Applications in Iridium-Catalyzed Allylic Alkylation of Indoles
Publication History
Publication Date:
19 May 2009 (online)
Abstract
A series of novel phosphoramidite ligands were synthesized from enantiopure BINOL and 2-methylindoline or 2-methyl-1,2,3,4-tetrahydroquinoline. These ligands were found to be efficient in iridium-catalyzed Friedel-Crafts reaction of indoles with allylic carbonates, affording branched products with high regio- and enantioselectivities. Strikingly, these ligands were demonstrated to be superior to the Feringa ligands when the ortho-substituted cinnamyl carbonates were used.
Key words
allylic alkylation - Friedel-Crafts reaction - indoles - iridium - phosphoramidites
The transition-metal-catalyzed allylic substitution reaction is one of the most frequently used methodologies to create chiral centers in organic synthesis. [¹] Despite the success so far, a challenging topic in this area is the regio- and enantioselective allylic alkylation of unsymmetrical substrates, particularly with palladium catalysts. [²] Since Takeuchi and co-workers first reported the iridium-catalyzed allylic alkylation reaction, [³] various chiral ligands such as oxazolinyl-phosphine, [4] binaphthol-based phosphoramidites, [5] phosphites, [6] diene ligands, [7] and PyBox [8] have been used for the allylic alkylation reaction of unsymmetrical allylic carbonates with high regio- and enantioselectivities. [9] In particular, the Feringa ligands, [¹0] phosphoramidites bearing a bis(1-arylethyl)amine moiety, were used most frequently. Recently, we reported the iridium-catalyzed allylic alkylation reaction of indoles. [¹¹] [¹²] With [Ir(cod)Cl]2/Feringa ligand L1 (Figure [¹] ) as catalyst, highly regio- and enantioselective Friedel-Crafts type allylic alkylation products were obtained for various unsymmetrical allylic carbonates. However, only poor enantioselectivities (70% and 31%, respectively) were obtained when o-methoxyphenyl- and 1-naphthyl-substituted allyl carbonates were used. [¹¹] The unfavorable ortho-substituent effect could also be found for many other type of nucleophiles, and a significant drop of product ee was observed for ortho-substituted cinnamyl carbonate. [5d] [p] [s] [t] Therefore, the design of phosphoramidite ligands to achieve high enantioselectivity for ortho-substituted phenylallylic substrates is urgent in this field. Given the ready availability of enantiopure 2-methylindoline [¹³] and 2-methyltetrahydroquinoline, [¹4] we recently synthesized a series of novel phosphoramidite ligands from enantiopure BINOL and 2-methylindoline or 2-methyl-1,2,3,4-tetrahydroquinoline. Remarkably, these ligands were found effective in iridium-catalyzed Friedel-Crafts reaction of indoles with allylic carbonates, even including the ortho-substituted cinnamyl carbonates. The absolute configuration of the alkylation product was also assigned. In this paper, we report the details of this study.
Figure 1 Chiral ligands L1, L4, and L-5
Scheme 1 The synthesis of enantiopure (R)-1a
The synthesis of enantiopure amines 1a and 1b was straightforward by following the known literature. Kinetic resolution of racemic amine 1a using N-tosyl-(S)-prolyl chloride resulted in predominant formation of (R,S)-4 and further acid hydrolysis of the latter afforded (R)-1a in 96% ee (Scheme [¹] ). [¹³] The (R)-2-methyltetrahydroquinoline (1b) was synthesized following the procedure recently developed by Zhou and co-workers through the iridium-catalyzed asymmetric hydrogenation of quinoline derivatives (Scheme [²] ). [¹4a] With the enantiopure amines in hand, the phosphoramidite ligands L2 and L3 were prepared from enantiopure 1,1′-bi-2-naphthol in a one-pot procedure (Scheme [³] ). [¹5]
Scheme 2 The synthesis of enantiopure (R)-1b
Scheme 3 The synthesis of ligands L2 and L3
The ligands L2 and L3 were examined for iridium-catalyzed Friedel-Crafts type reaction of indoles 8 with allylic carbonates 7 under the previously optimized reaction conditions: 2 mol% of [Ir(cod)Cl]2, 4 mol% of ligand, and 100 mol% of cesium carbonate in refluxing dioxane. [¹¹] The results are summarized in Table [¹] . The results from Feringa ligand L1 (Figure [¹] ) are also included for comparison. For the reaction of indole with 4-methoxyphenylallyl carbonate, ligands (R,R a)-L2, (R,R a)-L3, and (R,S a)-L3 afforded the products in relatively lower yields and ees (entries 3, 5, 6), compared to that of (S,S,S a)-L1. Unfortunately, the catalyst derived from (R,S a)-L2 only led to a low conversion (entry 4). Notably, chiral ligands L4 and L5 (Figure [¹] ) could not lead to formation of the desired product, but to a trace amount of 3-(4-methoxyphenyl)acrylaldehyde.
The new ligands (R,R a)-L2, (R,R a)-L3, and (R,S a)-L3 were tested in the reaction of different indoles and allylic carbonates. In general, the reaction with L3 proceeded in higher yields than that of L2. The similar ee values but different optical rotation of the products obtained from the reaction of (R,R a)-L3 and (R,S a)-L3, respectively, indicates that the enantiocontrol is dominated by the axial chirality in the ligands. The 2-phenylindole was demonstrated to be a suitable substrate in the reaction. With (S,S,S a)-L1, the desired branched alkylation product was isolated in 56% yield and 83% ee (entry 21).
To our great delight, the new ligands were found to be very efficient for the reaction of ortho-substituted phenylallyl carbonates, which normally afford poor ee values with Feringa ligand. For instance, the ee of 9da (2-methoxyphenyl derivative) was increased from 70% with (S,S,S a)-L1 to 90% with (R,R a)-L2 (entries 25-28). Significant improvement of the ees were also observed for 2-chlorophenyl (79% vs. 15%), 2-bromophenyl (85% vs. 4%), and 1-naphthyl (82% vs. 31%) substituted allyl carbonates (entries 29-40). These results are very attractive since this favorable ortho-effect might be found in the reactions with other type of nucleophiles.
To determine the absolute configuration of the alkylation product, the enantiopure bromo-containing compound 9ba, from the reaction with (S,S,S a)-L1 in entry 13, was obtained by recrystallization. An X-ray crystallographic analysis of enantiopure 9ba disclosed the absolute configuration as S [¹6] (Figure [²] ). The stereochemistry of the current Friedel-Crafts reaction with (S,S,S a)-L1 parallels that of previous decarboxylative allylic alkylation reactions. [5u]
Figure 2 X-ray crystal structure of (S)-9ba (thermal ellipsoids are set at 30% probability)
In summary, we have synthesized a series of phosphoramidite ligands from enantiopure BINOL and 2-methylindoline or 2-methyl-1,2,3,4-tetrahydroquinoline. These ligands have been tested in iridium-catalyzed Friedel-Crafts reaction of indoles with allylic carbonates, affording branched products with high regio- and enantioselectivities. The absolute configuration of the alkylation product was assigned for the first time. These ligands’ suitability towards ortho-substituted cinnamyl carbonates is particularly attractive for new ligand design. Further studies of the favorable ortho-effect in other type reactions are ongoing in our lab.
All manipulations were carried out in anhyd solvents under argon using standard Schlenk techniques. All glassware were oven- or flame-dried immediately prior to use. All reagents were obtained from commercial sources and used without further purification except indole (Chemical pure), which was purified by vacuum distillation. Petroleum ether (PE) used refers to the fraction boiling in the range 60-90 ˚C.
¹H NMR spectra were recorded at r.t. on the following spectrometers: Varian Mercury vx 300 (300 MHz) or Varian 400-MR (400 MHz) and with TMS (0 ppm) as reference. ¹³C NMR spectra were recorded on the following spectrometers: Varian Mercury vx 300 (75 MHz) or Varian 400-MR (100 MHz) with the solvent resonance (CDCl3, 77.0 ppm) as reference. Optical rotations were measured with a PerkinElmer 341 Polarimeter in a 1 dm thermostated cuvette using a Na lamp. IR spectra were obtained with a Nicolet AV-360 spectrophotometer. Mass spectra and high-resolution mass spectra (HRMS) were obtained on a Finnigan GC-MS 4021 and a Finnigan MAT-8430 spectrometer, respectively.
(R)-2-Methylindoline (1a) [¹³] and (R)-2-methyl-1,2,3,4-tetrahydroquinoline (1b) [¹4a] were prepared according to literature methods.
Phosphoramidite [( R , R a )-L2]; Typical Procedure
A flame-dried 250 mL, two-necked flask was equipped with a vacuum/argon stopcock and a magnetic stirring bar. The flask was charged with toluene (50 mL) and PCl3 (0.67 mL, 7.7 mmol), and then cooled to 0 ˚C. Another flame-dried, 25 mL flask was charged with 1a (1.03 g, 7.7 mmol), toluene (8 mL), and Et3N (1.8 mL, 12.9 mmol). This mixture was added dropwise to the above mentioned PCl3 solution at 0 ˚C. After the addition was complete, the reaction mixture was heated at 80 ˚C for 6 h, and then cooled slowly to -78 ˚C. To this mixture at -78 ˚C was added slowly a solution of (R a)-binaphthol (2.0 g, 7.0 mmol) and Et3N (3.5 mL, 25.2 mmol) in toluene (30 mL) and THF (6 mL). The resulting mixture was stirred at r.t. overnight, then filtered through Celite, and washed with Et2O. The organic phase was concentrated in vacuo. The product was purified by column chromatography over silica gel (PE-EtOAc-Et3N, 10:1:0.01, R f = 0.3). The solvent was evaporated in vacuo to afford 2.63 g (84%) of (R,R a)-L2 as a white powder (>95% de according to ¹H NMR spectrum); mp 201-204 ˚C; [α]D ²0 -315.4 (c 0.5, CHCl3).
IR (KBr): 3054, 2966, 2924, 2849, 1620, 1590, 1508, 1479, 1464, 1457, 1432, 1369, 1253, 1234, 1222, 1204, 1160, 1106, 1071, 1025, 986, 950, 939, 924, 823, 807, 748 cm-¹.
¹H NMR (300 MHz, CDCl3): δ = 8.01-7.86 (m, 4 H), 7.57 (d, J = 8.7 Hz, 1 H), 7.46-7.37 (m, 4 H), 7.32-7.23 (m, 3 H), 7.13 (d, J = 6.9 Hz, 1 H), 6.94-6.79 (m, 3 H), 3.73 (m, 1 H), 3.12 (dd, J = 8.4, 15.6 Hz, 1 H), 2.38 (d, J = 15.6 Hz, 1 H), 1.06 (d, J = 6.0 Hz, 3 H).
¹³C NMR (75 MHz, CDCl3): δ = 149.76, 149.70, 149.4, 145.2, 145.0, 132.77, 132.75, 132.60, 132.59, 131.5, 130.9, 130.64, 130.60, 130.5, 130.1, 128.3, 127.05, 127.01, 126.91, 126.22, 126.17, 125.5, 125.0, 124.7, 124.17, 124.10, 122.69, 122.67, 121.78, 121.76, 121.5, 121.06, 121.03, 112.7, 112.5, 55.84 (d, J = 4.6 Hz), 37.5, 23.23 (d, J = 1.7 Hz).
³¹P NMR (121 MHz, CDCl3): δ = 147.0.
HRMS-EI: m/z [M]+ calcd for C29H22NO2P: 447.1388; found: 447.1392.
O , O ′-[( S )-1,1′-Dinaphthyl-2,2′-diyl]- N -[( R )-2-methylindoline]phosphoramidite [( R , S a )-L2]
Yield: 87%; white powder; mp 167-171 ˚C; R f = 0.3 (PE-EtOAc-Et3N, 10:1:0.01); de >95%; [α]D ²0 +213.4 (c 0.5, CHCl3).
IR (KBr): 3049, 2973, 2953, 2919, 1618, 1590, 1505, 1478, 1459, 1430, 1369, 1325, 1313, 1251, 1232, 1220, 1205, 1106, 1070, 1042, 1025, 982, 949, 906, 819,797, 789, 755, 747 cm-¹.
¹H NMR (300 MHz, CDCl3): δ = 7.97 (d, J = 8.7 Hz, 1 H), 7.91 (d, J = 8.1 Hz, 1 H), 7.80 (d, J = 8.1 Hz, 1 H), 7.64 (d, J = 8.4 Hz, 1 H), 7.54 (d, J = 8.4 Hz, 1 H), 7.43-7.35 (m, 4 H), 7.25 (m, 2 H), 7.11 (d, J = 9.0 Hz, 1 H), 7.07 (d, J = 8.1 Hz, 1 H), 6.79-6.71 (m, 2 H), 6.62-6.57 (m, 1 H), 4.40 (m, 1 H), 3.31 (dd, J = 9.0, 15.0 Hz, 1 H), 2.50 (d, J = 15.3 Hz, 1 H), 0.80 (d, J = 6.3 Hz, 3 H).
¹³C NMR (75 MHz, CDCl3): δ = 150.03, 149.95, 149.0, 145.7, 145.5, 132.83, 132.81, 132.50, 132.48, 131.5, 131.08, 131.04, 130.8, 130.4, 129.6, 128.3, 128.2, 127.0, 126.8, 126.7, 126.2, 126.0, 125.0, 124.8, 124.5, 124.3, 124.2, 122.35, 122.32, 122.1, 121.72, 121.70, 121.1, 113.5, 113.4, 55.43 (d, J = 8.8 Hz), 37.71 (d, J = 1.7 Hz), 23.14 (d, J = 2.9 Hz).
³¹P NMR (121 MHz, CDCl3): δ = 149.4.
HRMS-EI: m/z [M]+ calcd for C29H22NO2P: 447.1388; found: 447.1386.
O , O ′-[( R )-1,1′-Dinaphthyl-2,2′-diyl]- N -[( R )-2-methyl-1,2,3,4-tetrahydroquinoline]phosphoramidite [( R , R a )-L3]
Yield: 92%; white solid; mp 210-212 ˚C; R f = 0.4 (PE-EtOAc-Et3N, 10:1:0.01); de >95%; [α]D ²0 -255.2 (c 1.0, CHCl3).
IR (KBr): 3055, 2976, 2941, 1620, 1590, 1575, 1508, 1490, 1465, 1448, 1432, 1369, 1326, 1311, 1229, 1201, 1161, 1120, 1072, 1023, 987, 952, 944, 940, 930, 869, 861, 823, 806, 786, 749 cm-¹.
¹H NMR (300 MHz, CDCl3): δ = 8.01 (d, J = 9.0 Hz, 1 H), 7.94-7.89 (m, 3 H), 7.60 (d, J = 8.7 Hz, 1 H), 7.55 (dd, J = 3.6, 8.1 Hz, 1 H), 7.42 (dd, J = 3.6, 8.1 Hz, 4 H), 7.31-7.21 (m, 3 H), 7.11-7.06 (m, 2 H), 6.93 (t, J = 7.2 Hz, 1 H), 3.71 (m, 1 H), 2.78 (t, J = 4.5 Hz, 2 H), 2.04-1.92 (m, 1 H), 1.45-1.38 (m, 1 H), 0.94 (d, J = 6.6 Hz, 3 H).
¹³C NMR (75 MHz, CDCl3): δ = 150.0, 149.9, 149.4, 139.9, 139.6, 132.75, 132.73, 132.7, 131.50, 131.48, 130.61, 130.55, 129.9, 129.8, 128.3, 128.2, 127.2, 127.1, 126.38, 126.35, 126.26, 126.20, 126.15, 126.06, 125.0, 124.6, 124.11, 124.03, 122.12, 122.09, 121.8, 121.66, 121.63, 121.31, 121.28, 119.8, 119.3, 45.73 (d, J = 2.3 Hz), 27.9, 22.8, 19.0.
³¹P NMR (121 MHz, CDCl3): δ = 141.0.
HRMS-EI: m/z [M]+ calcd for C30H24NO2P: 461.1545; found: 461.1548.
O , O ′-[( S )-1,1′-Dinaphthyl-2,2′-diyl]- N -[( R )-2-methyl-1,2,3,4-tetrahydroquinoline]phosphoramidite [( R , S a )-L3]
Yield: 87%; white solid; mp 200-202 ˚C; R f = 0.4 (PE-EtOAc-Et3N, 10:1:0.01); de >95%; [α]D ²0 +241.9 (c 1.0, CHCl3).
IR (KBr): 3055, 2974, 1619, 1587, 1577, 1505, 1491, 1463, 1453, 1431, 1378, 1360, 1326, 1307, 1228, 1204, 1190, 1155, 1133, 1116, 1096, 1071, 1054, 1027, 983, 944, 862, 821, 799, 792, 782, 748 cm-¹.
¹H NMR (300 MHz, CDCl3): δ = 7.94-7.85 (m, 4 H), 7.47-7.18 (m, 9 H), 7.08-6.93 (m, 3 H), 3.88-3.82 (m, 1 H), 2.75 (m, 2 H), 1.97-1.85 (m, 1 H), 1.49-1.42 (m, 1 H), 0.83 (d, J = 6.6 Hz, 3 H).
¹³C NMR (75 MHz, CDCl3): δ = 149.54, 149.45, 149.0, 139.8, 139.5, 132.7, 132.5, 131.4, 130.7, 130.4, 129.6, 128.32, 128.25, 127.11, 127.05, 127.0, 126.2, 126.1, 126.0, 124.8, 124.6, 124.05, 123.98, 122.21, 122.16, 121.9, 121.4, 121.1, 45.2, 28.2, 22.2, 17.6.
³¹P NMR (121 MHz, CDCl3): δ = 143.8.
HRMS-EI: m/z [M]+ calcd for C30H24NO2P: 461.1545; found: 461.1549.
Iridium-Catalyzed Allylic Alkylation of Indoles; General Procedure
In a dry Schlenk tube filled with argon, [Ir(COD)Cl]2 (2.7 mg, 0.004 mmol, 2 mol%), phosphoramidite ligand (0.008 mmol, 4 mol%), and propylamine (0.3 mL) were dissolved in THF (0.5 mL). The reaction mixture was heated at 50 ˚C for 30 min and then the volatile solvents were removed under vacuum to give a yellow solid. Then, allylic carbonate 7 (0.20 mmol), indole 8 (0.40 mmol, 200 mol%), Cs2CO3 (65.2 mg, 0.20 mmol), and 1,4-dioxane (2.0 mL) were added. The mixture was refluxed until the carbonate was fully consumed, monitored by TLC or ¹H NMR spectrum. The crude reaction mixture was then filtered through Celite and the solvent was removed under reduced pressure. The ratio of regioisomers (branched to linear, b/l) was determined by ¹H NMR of the crude reaction mixture. The crude residue was purified by flash column chromatography over silica gel (hexanes-EtOAc or hexanes-Et2O) to give the products.
3-[1-(4-Methoxyphenyl)allyl]-1 H -indole (9aa)
(S,S,S a)-L1 was used; b/l: >99:1; 9aa was obtained with 92% ee [Daicel CHIRALCEL OD-H (0.46 cm × 25 cm); hexanes-propan-2-ol, 90:10; flow rate: 1.0 mL/min; detection wavelength: 230 nm; t R = 13.46 (minor), 13.89 (major) min]; yield: 43.1 mg (82%); yellow oil; R f = 0.3 (hexanes-EtOAc, 10:1); [α]D ²0 -2.8 (c 1.0, CHCl3).
IR (KBr): 3420, 3058, 2957, 2836, 1664, 1637, 1608, 1510, 1457, 1247, 1178, 1034, 823, 743 cm-¹.
¹H NMR (300 MHz, CDCl3): δ = 7.97 (br s, 1 H), 7.43 (d, J = 7.8 Hz, 1 H), 7.35 (d, J = 8.1 Hz, 1 H), 7.26-7.16 (m, 3 H), 7.05 (t, J = 7.5 Hz, 1 H), 6.88-6.85 (m, 3 H), 6.36 (ddd, J = 6.9, 9.9, 17.1 Hz, 1 H), 5.20 (d, J = 10.2 Hz, 1 H), 5.08 (d, J = 17.1 Hz, 1 H), 4.94 (d, J = 7.2 Hz, 1 H), 3.81 (s, 3 H).
¹³C NMR (75 MHz, CDCl3): δ = 140.7, 136.6, 135.3, 129.3, 126.7, 122.4, 121.9, 119.8, 119.2, 118.7, 115.1, 113.6, 111.0, 55.2, 46.1.
HRMS-EI: m/z [M]+ calcd for C18H17NO: 263.1310; found: 263.1322.
5-Methoxy-3-[1-(4-methoxyphenyl)allyl]-1 H -indole (9ab)
(S,S,S a)-L1 was used; b/l: >99:1; 9ab was obtained with 89% ee [Daicel CHIRALPAK AD-H (0.46 cm × 25 cm); hexanes-propan-2-ol, 90:10; flow rate: 1.0 mL/min; detection wavelength: 230 nm; t R = 20.64 (minor), 33.39 (major) min]; yield: 49.8 mg (85%); yellow oil; R f = 0.3 (hexanes-EtOAc, 10:1); [α]D ²0 -20.8 (c 0.5, CHCl3).
IR (KBr): 3419, 3075, 3001, 2954, 2934, 2835, 1625, 1610, 1583, 1510, 1484, 1455, 1440, 1300, 1247, 1211, 1176, 1034, 923, 829, 800 cm-¹.
¹H NMR (300 MHz, CDCl3): δ = 7.90 (br s, 1 H), 7.25-7.17 (m, 3 H), 6.86-6.80 (m, 5 H), 6.31 (ddd, J = 6.9, 10.2, 17.1 Hz, 1 H), 5.17 (d, J = 10.2 Hz, 1 H), 5.05 (d, J = 17.1 Hz, 1 H), 4.86 (d, J = 7.2 Hz, 1 H), 3.79 (s, 3 H), 3.75 (s, 3 H).
¹³C NMR (75 MHz, CDCl3): δ = 157.9, 153.5, 140.6, 135.2, 131.7, 129.3, 127.1, 123.2, 118.2, 115.1, 113.6, 111.9, 111.7, 101.7, 55.7, 55.2, 46.0.
HRMS-EI: m/z [M]+ calcd for C18H17NO: 293.1416; found: 293.1417.
3-[1-(4-Bromophenyl)allyl]-1 H -indole (9ba)
(S,S,S a)-L1 was used; b/l: >99:1; 9ba was obtained with 90% ee (>99% ee after recrystallization from PE-EtOAc) [Daicel CHIRALPAK AD-H (0.46 cm × 25 cm); hexanes-propan-2-ol, 90:10; flow rate: 1.0 mL/min; detection wavelength: 230 nm; t R = 10.23 (minor), 10.92 (major) min]; yield: 50.6 mg (81%); white solid; mp 88-90 ˚C, R f = 0.3 (hexanes-Et2O, 10:1); [α]D ²0 -6.1 (c 0.5, CHCl3).
IR (KBr): 3418, 3058, 1637, 1618, 1486, 1456, 1417, 1353, 1336, 1220, 1095, 1072, 1011, 910, 766, 743 cm-¹.
¹H NMR (300 MHz, CDCl3): δ = 7.98 (br s, 1 H), 7.41-7.33 (m, 4 H), 7.20-7.13 (m, 3 H), 7.03 (t, J = 7.5 Hz, 1 H), 6.87 (d, J = 2.1 Hz, 1 H), 6.30 (ddd, J = 7.2, 10.2, 17.1 Hz, 1 H), 5.20 (dt, J = 1.2, 10.2 Hz, 1 H), 5.04 (dt, J = 1.2, 17.1 Hz, 1 H), 4.91 (d, J = 7.2 Hz, 1 H).
¹³C NMR (75 MHz, CDCl3): δ = 142.1, 139.8, 136.5, 131.4, 130.2, 126.5, 122.4, 122.2, 120.0, 119.6, 117.8, 115.9, 111.1, 46.3.
HRMS-EI: m/z [M]+ calcd for C17H14BrN: 311.0310; found: 311.0312.
3-[1-(4-(Trifluoromethyl)phenyl)allyl)-1 H -indole (9ca)
(S,S,S a)-L1 and 7c (0.41 mmol) were used; b/l: >99:1; 9ca was obtained with 87% ee [Daicel CHIRALCEL OD-H (0.46 cm × 25 cm); hexanes-propan-2-ol, 98:2; flow rate: 1.0 mL/min; detection wavelength: 230 nm; t R = 35.50 (major), 38.16 (minor) min]; yield: 76.0 mg (63%); yellow oil; R f = 0.2 (hexanes-EtOAc, 10:1); [α]D ²0 +8.2 (c 0.5, CHCl3, note: the optical rotation was incorrectly reported previously¹¹).
IR (KBr): 3415, 3061, 2903, 2933, 2874, 1714, 1639, 1618, 1488, 1457, 1419, 1327, 1162, 1110, 1068, 1018, 923, 856, 826, 797 cm-¹.
¹H NMR (300 MHz, CDCl3): δ = 7.98 (br s, 1 H), 7.55-7.01 (m, 8 H), 6.89 (s, 1 H), 6.32 (ddd, J = 7.2, 9.6, 17.1 Hz, 1 H), 5.23 (d, J = 9.6, 1 H), 5.06 (d, J = 17.1 Hz, 1 H), 5.01 (d, J = 7.2 Hz, 1 H).
¹³C NMR (75 MHz, CDCl3): δ = 147.2, 139.5, 136.6, 128.7, 128.3, 126.4, 125.3, 125.2, 122.5, 122.3, 119.5, 119.5, 117.5, 116.3, 111.2, 46.7.
HRMS-EI: m/z [M]+ calcd for C18H14F3N: 301.1078; found: 301.1085.
3-[1-(4-Methoxyphenyl)allyl]-2-phenyl-1 H -indole (9ac)
(S,S,S a)-L1 was used; b/l: >99:1; 9ac was obtained with 83% ee [Daicel CHIRALPAK AS-H (0.46 cm × 25 cm); hexanes-propan-2-ol, 90:10; flow rate: 0.6 mL/min; detection wavelength: 254 nm; t R = 15.65 (major), 17.51 (minor) min]; yield: 37.9 mg (56%); white solid; mp 148-150 ˚C; R f = 0.3 (hexanes-EtOAc, 10:1); [α]D ²0 -30.2 (c 0.5, CHCl3).
IR (KBr): 3406, 3057, 2956, 2924, 2853, 1606, 1581, 1509, 1454, 1304, 1245, 1177, 1032, 916, 821, 743, 764, 700 cm-¹.
¹H NMR (300 MHz, CDCl3): δ = 8.07 (s, 1 H), 7.53-7.36 (m, 7 H), 7.22 (d, J = 8.7 Hz, 2 H), 7.16 (t, J = 7.8 Hz, 1 H), 6.99 (t, J = 7.8 Hz, 1 H), 6.80 (d, J = 9.0 Hz, 2 H), 6.49 (ddd, J = 6.9, 10.2, 17.1 Hz, 1 H), 5.20 (d, J = 9.9 Hz, 1 H), 5.07 (d, J = 8.7 Hz, 1 H), 5.06 (d, J = 16.8 Hz, 1 H), 3.76 (s, 3 H).
¹³C NMR (75 MHz, CDCl3): δ = 157.7, 140.3, 136.2, 125.3, 135.2, 132.9, 129.2, 128.7, 128.4, 127.9, 127.8, 122.0, 121.3, 119.4, 115.8, 113.8, 113.5, 110.9, 55.1, 45.0.
HRMS-EI: m/z [M]+ calcd for C24H21NO: 339.1623; found: 339.1621.
3-[1-(2-Methoxyphenyl)allyl]-1 H -indole (9da)
(R,R a)-L2 was used; b/l: >99:1; 9da was obtained with 90% ee [Daicel CHIRALCEL OD-H (0.46 cm × 25 cm); hexanes-propan-2-ol, 98:2; flow rate: 1.0 mL/min; detection wavelength: 254 nm; t R = 27.49 (minor), 32.31 (major) min]; yield: 24.9 mg (47%); yellow oil; R f = 0.3 (hexanes-EtOAc, 10:1); [α]D ²0 +7.8 (c 0.5, CHCl3).
IR (KBr): 3418, 3078, 3059, 3003, 2955, 2934, 2837, 1637, 1619, 1599, 1587, 1548, 1490, 1457, 1438, 1419, 1244, 1105, 1029, 917, 743 cm-¹.
¹H NMR (300 MHz, CDCl3): δ = 7.63 (br s, 1 H), 7.43 (d, J = 7.8 Hz, 1 H), 7.19-7.08 (m, 4 H), 7.00 (t, J = 7.2 Hz, 1 H), 6.87-6.81 (m, 2 H), 6.71 (d, J = 1.2 Hz, 1 H), 6.29 (ddd, J = 6.3, 10.2, 16.8 Hz, 1 H), 5.43 (d, J = 6.0 Hz, 1 H), 5.14 (d, J = 10.2 Hz, 1 H), 4.98 (d, J = 16.8 Hz, 1 H), 3.76 (s, 3 H).
¹³C NMR (75 MHz, CDCl3): δ = 156.7, 140.0, 136.4, 131.4, 129.2, 127.3, 126.9, 122.5, 121.7, 120.4, 119.7, 119.0, 118.0, 115.0, 110.9, 110.6, 55.5, 38.7.
HRMS-EI: m/z [M]+ calcd for C18H17NO: 263.1310; found: 263.1319.
3-[1-(2-Chlorophenyl)allyl]-1 H -indole (9ea)
(R,R a)-L3 was used; b/l: >99:1; 9ea was obtained with 79% ee [Daicel CHIRALCEL OD-H (0.46 cm × 25 cm); hexanes-propan-2-ol, 98:2; flow rate: 0.8 mL/min; detection wavelength: 254 nm; t R = 31.07 (minor), 33.48 (major) min]; yield: 29.4 mg (55%); yellow oil; R f = 0.2 (hexanes-Et2O, 10:1); [α]D ²0 +44.0 (c 0.5, CHCl3).
IR (KBr): 3418, 3059, 3008, 2980, 2924, 2854, 1637, 1619, 1592, 1571, 1548, 1471, 1457, 1442, 1418, 1352, 1338, 1245, 1221, 1125, 1095, 1046, 1036, 1011, 995, 921, 801, 743 cm-¹.
¹H NMR (300 MHz, CDCl3): δ = 7.96 (br s, 1 H), 7.41-7.31 (m, 3 H), 7.19-7.12 (m, 4 H), 7.03 (t, J = 7.2 Hz, 1 H), 6.89 (d, J = 2.4 Hz, 1 H), 6.28 (ddd, J = 6.6, 9.9, 17.1 Hz, 1 H), 5.48 (d, J = 6.0 Hz, 1 H), 5.23 (d, J = 9.9 Hz, 1 H), 5.05 (d, J = 16.8 Hz, 1 H).
¹³C NMR (75 MHz, CDCl3): δ = 140.3, 138.7, 136.5, 133.9, 129.9, 129.5, 127.6, 126.7, 126.8, 122.7, 122.1, 119.6, 119.4, 117.4, 116.2, 111.0, 42.7.
HRMS-EI: m/z [M]+ calcd for C17H14ClN: 267.0815; found: 267.0814.
3-[1-(2-Bromophenyl)allyl]-1 H -indole (9fa)
(R,R a)-L3 was used; b/l: >99:1; 9fa was obtained with 85% ee [Daicel CHIRALPAK AD-H (0.46 cm × 25 cm); hexanes-propan-2-ol, 90:10; flow rate: 1.0 mL/min; detection wavelength: 254 nm; t R = 8.15 (minor), 11.24 (major) min]; yield: 25.5 mg (41%); yellow oil; R f = 0.2 (hexanes-Et2O, 10:1); [α]D ²0 +86.8 (c 0.5, CHCl3).
IR (KBr): 3418, 3056, 2959, 2923, 2853, 1636, 1459, 1437, 1417, 1337, 1221, 1095, 1022, 921, 743 cm-¹.
¹H NMR (300 MHz, CDCl3): δ = 8.00 (br s, 1 H), 7.59 (d, J = 7.5 Hz, 1 H), 7.36 (t, J = 8.1 Hz, 2 H), 7.19-7.00 (m, 5 H), 6.91 (d, J = 2.1 Hz, 1 H), 6.27 (ddd, J = 6.3, 9.9, 16.8 Hz, 1 H), 5.46 (dd, J = 1.2, 6.0 Hz, 1 H), 5.24 (dt, J = 1.5, 9.9 Hz, 1 H), 5.00 (dt, J = 1.5, 16.8 Hz, 1 H).
¹³C NMR (75 MHz, CDCl3): δ = 142.0, 138.8, 136.6, 132.8, 130.1, 127.9, 127.4, 126.7, 124.8, 122.7, 122.1, 119.7, 119.4, 117.6, 116.3, 111.0, 45.5.
HRMS-EI: m/z [M]+ calcd for C17H14BrN: 311.0310; found: 311.0311.
5-Methoxy-3-[1-(naphthalen-1-yl)allyl]-1 H -indole (9gb)
(R,S a)-L3 was used; b/l: >99:1; 9gb was obtained with 82% ee [Daicel CHIRALPAK AD-H (0.46 cm × 25 cm); hexanes-propan-2-ol, 90:10; flow rate: 1.0 mL/min; detection wavelength: 254 nm; t R = 16.84 (major), 30.83 (minor) min]; yield: 56.9 mg (92%); yellow oil; R f = 0.2 (hexanes-Et2O, 10:1); [α]D ²0 +59.2 (c 1.0, CHCl3).
IR (KBr): 3424, 3051, 3001, 2934, 2830, 1718, 1636, 1625, 1596, 1583, 1508, 1484, 1456, 1438, 1209, 1172, 1045, 1027, 921, 800, 781 cm-¹.
¹H NMR (300 MHz, CDCl3): δ = 8.08 (d, J = 7.5 Hz, 1 H), 7.85-7.70 (m, 3 H), 7.44-7.37 (m, 4 H), 7.17-7.12 (m, 1 H), 6.89 (d, J = 2.4 Hz, 1 H), 6.82 (dd, J = 2.7, 8.7 Hz, 1 H), 6.57 (d, J = 2.1 Hz, 1 H), 6.40 (ddd, J = 6.0, 9.9, 16.8 Hz, 1 H), 5.66 (d, J = 6.3 Hz, 1 H), 5.24 (d, J = 10.2 Hz, 1 H), 5.00 (d, J = 16.8 Hz, 1 H), 3.71 (s, 3 H).
¹³C NMR (75 MHz, CDCl3): δ = 153.6, 139.7, 138.7, 133.9, 131.7, 131.6, 128.6, 127.2, 127.0, 125.8, 125.7, 125.4, 125.3, 124.2, 124.1, 117.5, 116.2, 111.8, 111.7, 101.5, 55.7, 42.1.
HRMS-EI: m/z [M]+ calcd for C22H19NO: 313.1467; found: 313.1472.
Acknowledgment
We thank the NSFC (20872159, 20821002), National Basic Research Program of China (973 Program 2009CB825300), and the STCSM (07pj14106, 07JC14063) for generous financial support.
- For reviews, see:
- 1a
Trost BM.Van Vranken DL. Chem. Rev. 1996, 96: 395 - 1b
Trost BM.Crawley ML. Chem. Rev. 2003, 103: 2921 - 1c
Lu Z.Ma S. Angew. Chem. Int. Ed. 2008, 47: 258 - Some exceptional examples:
- 2a
Hayashi T.Kawatsura M.Uozumi Y. J. Am. Chem. Soc. 1998, 120: 1681 - 2b
Prétôt R.Pfaltz A. Angew. Chem. Int. Ed. 1998, 37: 323 - 2c
You S.-L.Zhu X.-Z.Luo Y.-M.Hou X.-L.Dai L.-X. J. Am. Chem. Soc. 2001, 123: 7471 - 2d
Yan XX.Liang CG.Zhang Y.Hong W.Cao BX.Dai LX.Hou XL. Angew. Chem. Int. Ed. 2005, 44: 6544 - 2e
Zheng W.-H.Zheng B.-H.Zhang Y.Hou X.-L. J. Am. Chem. Soc. 2007, 129: 7718 - 2f
Zhang K.Peng Q.Hou X.-L.Wu Y.-D. Angew. Chem. Int. Ed. 2008, 47: 1741 - 3
Takeuchi R.Kashio M. Angew. Chem., Int. Ed. Engl. 1997, 36: 263 - 4
Janssen JP.Helmchen G. Tetrahedron Lett. 1997, 38: 8025 - 5a
Bartels B.Helmchen G. Chem. Commun. 1999, 741 - 5b
Kiener CA.Shu C.Incarvito C.Hartwig JF. J. Am. Chem. Soc. 2003, 125: 14272 - 5c
Bartels B.García-Yebra C.Helmchen G. Eur. J. Org. Chem. 2003, 1097 - 5d
López F.Ohmura T.Hartwig JF. J. Am. Chem. Soc. 2003, 125: 3426 - 5e
Kiener CA.Shu C.Incarvito C.Hartwig JF. J. Am. Chem. Soc. 2003, 125: 14272 - 5f
Tissot-Croset K.Polet D.Alexakis A. Angew. Chem. Int. Ed. 2004, 43: 2426 - 5g
Lipowsky G.Miller N.Helmchen G. Angew. Chem. Int. Ed. 2004, 43: 4595 - 5h
Alexakis A.Polet D. Org. Lett. 2004, 6: 3529 - 5i
Shu C.Hartwig JF. Angew. Chem. Int. Ed. 2004, 43: 4794 - 5j
Shu C.Leitner A.Hartwig JF. Angew. Chem. Int. Ed. 2004, 43: 4797 - 5k
Polet D.Alexakis A. Org. Lett. 2005, 7: 1621 - 5l
Pouy J.Hartwig JF. J. Am. Chem. Soc. 2005, 127: 15506 - 5m
Graening T.Hartwig JF. J. Am. Chem. Soc. 2005, 127: 17192 - 5n
Shekhar S.Trantow B.Leitner A.Hartwig JF. J. Am. Chem. Soc. 2006, 128: 11770 - 5o
Schelwies M.Dübon P.Helmchen G. Angew. Chem. Int. Ed. 2006, 45: 2466 - 5p
Polet D.Alexakis A.Tissot-Croset K.Corminboeuf C.Ditrich K. Chem. Eur. J. 2006, 12: 3596 - 5q
Alexakis A.Hajjaji SE.Polet D.Rathgeb X. Org. Lett. 2007, 9: 3393 - 5r
Weix DJ.Hartwig JF. J. Am. Chem. Soc. 2007, 129: 7720 - 5s
Yamashita Y.Gopalarathnam A.Hartwig JF. J. Am. Chem. Soc. 2007, 129: 7508 - 5t
Pouy MJ.Leitner A.Weix DJ.Ueno S.Hartwig JF. Org. Lett. 2007, 9: 3949 - 5u
He H.Zheng X.-J.Li Y.Dai L.-X.You S.-L. Org. Lett. 2007, 9: 4339 - 5v
Markovic D.Hartwig JF. J. Am. Chem. Soc. 2007, 129: 11680 - 5w
Bondzic BP.Farwick A.Liebich J.Eilbracht P. Org. Biomol. Chem. 2008, 6: 3723 - 5x
Ueno S.Hartwig JF. Angew. Chem. Int. Ed. 2008, 47: 1928 - 5y
Förster S.Tverskoy O.Helmchen G. Synlett 2008, 2803 - 5z
Dübon P.Schelwies M.Helmchen G. Chem. Eur. J. 2008, 14: 6722 - (aa)
Spiess S.Welter C.Franck G.Taquet J.-P.Helmchen G. Angew. Chem. Int. Ed. 2008, 47: 7652 - (ab)
Onodera G.Watabe K.Matsubara M.Oda K.Kezuka S.Takeuchi R. Adv. Synth. Catal. 2008, 350: 2725 - 6a
Fuji K.Kinoshita N.Tanaka K.Kawabata T. Chem. Commun. 1999, 2289 - 6b
Kinoshita N.Marx KH.Tanaka K.Tsubaki K.Kawabata T.Yoshikai N.Nakamura E.Fuji K. J. Org. Chem. 2004, 69: 7960 - 6c
Kanayama T.Yoshida K.Miyabe H.Takemoto Y. Angew. Chem. Int. Ed. 2003, 42: 2054 - 7
Fischer C.Defieber C.Suzuki T.Carreira EM. J. Am. Chem. Soc. 2004, 126: 1628 - 8a
Miyabe H.Matsumura A.Moriyama K.Takemoto Y. Org. Lett. 2004, 6: 4631 - 8b
Miyabe H.Yoshida K.Reddy VK.Takemoto Y. J. Org. Chem. 2009, 74: 305 - For reviews, see:
- 9a
Takeuchi R. Synlett 2002, 1954 - 9b
Miyabe H.Takemoto Y. Synlett 2005, 1641 - 9c
Takeuchi R.Kezuka S. Synthesis 2006, 3349 - 9d
Helmchen G.Dahnz A.Dübon P.Schelwies M.Weihofen R. Chem. Commun. 2007, 675 - For reviews, see:
- 10a
Feringa BL. Acc. Chem. Res. 2000, 33: 346 - 10b
Minnaard AJ.Feringa BL.Lefort L.de Vries JG. Acc. Chem. Res. 2007, 40: 1267 - 11
Liu W.-B.He H.Dai L.-X.You S.-L. Org. Lett. 2008, 10: 1815 - For transition metal catalyzed allylic alkylation of indoles, see:
- 12a
Bandini M.Melloni A.Umani-Ronchi A. Org. Lett. 2004, 6: 3199 - 12b
Bandini M.Melloni A.Piccinelli F.Sinisi R.Tommasi S.Umani-Ronchi A. J. Am. Chem. Soc. 2006, 128: 1424 - 12c
Ma S.Yu S.Peng Z.Guo H. J. Org. Chem. 2006, 71: 9865 - 12d
Trost BM.Quancard J. J. Am. Chem. Soc. 2006, 128: 6314 - 12e
Cheung HY.Yu W.-Y.Lam FL.Au-Yeung TT.-L.Zhou Z.Chan TH.Chan ASC. Org. Lett. 2007, 9: 4295 - 12f
Zaitsev AB.Gruber S.Plüss PA.Pregosin PS.Veiros LF.Wörle M. J. Am. Chem. Soc. 2008, 130: 11604 - 12g
Usui I.Schmidt S.Keller M.Breit B. Org. Lett. 2008, 10: 1207 - 12h
Kagawa N.Malerich JP.Rawal VH. Org. Lett. 2008, 10: 2381 - 13
Krasnov VP.Levit GL.Bukrina IM.Andreeva IN.Sadretdinova LS.Korolyova MA.Kodess MI.Charushin VN.Chupakhin ON. Tetrahedron: Asymmetry 2003, 14: 1985 - 14a
Lu S.-M.Han X.-W.Zhou Y.-G. Adv. Synth. Catal. 2004, 346: 909 - 14b
Lu S.-M.Wang Y.-Q.Han X.-W.Zhou Y.-G. Angew. Chem. Int. Ed. 2006, 45: 2260 - 14c
Zhou Y.-G. Acc. Chem. Res. 2007, 40: 1357 - 14d
Wang Z.-J.Deng G.-J.Li Y.He Y.-M.Tang W.-J.Fan Q.-H. Org. Lett. 2007, 9: 1243 - 14e
Wang X.-B.Zhou Y.-G. J. Org. Chem. 2008, 73: 5640 - 14f
Li Z.-W.Wang T.-L.He Y.-M.Wang Z.-J.Fan Q.-H.Pan J.Xu L.-J. Org. Lett. 2008, 10: 5265 - 14g
Zhou H.Li Z.Wang Z.Wang T.Xu L.He Y.Fan Q.-H.Pan J.Gu L.Chan ASC. Angew. Chem. Int. Ed. 2008, 47: 8464 - 15a
Alexakis A.Rosset S.Allamand J.March S.Guillen F.Benhaim C. Synlett 2001, 1375 - 15b
Naasz R.Arnold LA.Minnaard AJ.Feringa BL. Angew. Chem. Int. Ed. 2001, 40: 927 - 15c
Polet D.Alexakis A. Synthesis 2004, 2586
References
CCDC 722528 contains the supplementary crystallographic data for 9ba. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data request/cif.
- For reviews, see:
- 1a
Trost BM.Van Vranken DL. Chem. Rev. 1996, 96: 395 - 1b
Trost BM.Crawley ML. Chem. Rev. 2003, 103: 2921 - 1c
Lu Z.Ma S. Angew. Chem. Int. Ed. 2008, 47: 258 - Some exceptional examples:
- 2a
Hayashi T.Kawatsura M.Uozumi Y. J. Am. Chem. Soc. 1998, 120: 1681 - 2b
Prétôt R.Pfaltz A. Angew. Chem. Int. Ed. 1998, 37: 323 - 2c
You S.-L.Zhu X.-Z.Luo Y.-M.Hou X.-L.Dai L.-X. J. Am. Chem. Soc. 2001, 123: 7471 - 2d
Yan XX.Liang CG.Zhang Y.Hong W.Cao BX.Dai LX.Hou XL. Angew. Chem. Int. Ed. 2005, 44: 6544 - 2e
Zheng W.-H.Zheng B.-H.Zhang Y.Hou X.-L. J. Am. Chem. Soc. 2007, 129: 7718 - 2f
Zhang K.Peng Q.Hou X.-L.Wu Y.-D. Angew. Chem. Int. Ed. 2008, 47: 1741 - 3
Takeuchi R.Kashio M. Angew. Chem., Int. Ed. Engl. 1997, 36: 263 - 4
Janssen JP.Helmchen G. Tetrahedron Lett. 1997, 38: 8025 - 5a
Bartels B.Helmchen G. Chem. Commun. 1999, 741 - 5b
Kiener CA.Shu C.Incarvito C.Hartwig JF. J. Am. Chem. Soc. 2003, 125: 14272 - 5c
Bartels B.García-Yebra C.Helmchen G. Eur. J. Org. Chem. 2003, 1097 - 5d
López F.Ohmura T.Hartwig JF. J. Am. Chem. Soc. 2003, 125: 3426 - 5e
Kiener CA.Shu C.Incarvito C.Hartwig JF. J. Am. Chem. Soc. 2003, 125: 14272 - 5f
Tissot-Croset K.Polet D.Alexakis A. Angew. Chem. Int. Ed. 2004, 43: 2426 - 5g
Lipowsky G.Miller N.Helmchen G. Angew. Chem. Int. Ed. 2004, 43: 4595 - 5h
Alexakis A.Polet D. Org. Lett. 2004, 6: 3529 - 5i
Shu C.Hartwig JF. Angew. Chem. Int. Ed. 2004, 43: 4794 - 5j
Shu C.Leitner A.Hartwig JF. Angew. Chem. Int. Ed. 2004, 43: 4797 - 5k
Polet D.Alexakis A. Org. Lett. 2005, 7: 1621 - 5l
Pouy J.Hartwig JF. J. Am. Chem. Soc. 2005, 127: 15506 - 5m
Graening T.Hartwig JF. J. Am. Chem. Soc. 2005, 127: 17192 - 5n
Shekhar S.Trantow B.Leitner A.Hartwig JF. J. Am. Chem. Soc. 2006, 128: 11770 - 5o
Schelwies M.Dübon P.Helmchen G. Angew. Chem. Int. Ed. 2006, 45: 2466 - 5p
Polet D.Alexakis A.Tissot-Croset K.Corminboeuf C.Ditrich K. Chem. Eur. J. 2006, 12: 3596 - 5q
Alexakis A.Hajjaji SE.Polet D.Rathgeb X. Org. Lett. 2007, 9: 3393 - 5r
Weix DJ.Hartwig JF. J. Am. Chem. Soc. 2007, 129: 7720 - 5s
Yamashita Y.Gopalarathnam A.Hartwig JF. J. Am. Chem. Soc. 2007, 129: 7508 - 5t
Pouy MJ.Leitner A.Weix DJ.Ueno S.Hartwig JF. Org. Lett. 2007, 9: 3949 - 5u
He H.Zheng X.-J.Li Y.Dai L.-X.You S.-L. Org. Lett. 2007, 9: 4339 - 5v
Markovic D.Hartwig JF. J. Am. Chem. Soc. 2007, 129: 11680 - 5w
Bondzic BP.Farwick A.Liebich J.Eilbracht P. Org. Biomol. Chem. 2008, 6: 3723 - 5x
Ueno S.Hartwig JF. Angew. Chem. Int. Ed. 2008, 47: 1928 - 5y
Förster S.Tverskoy O.Helmchen G. Synlett 2008, 2803 - 5z
Dübon P.Schelwies M.Helmchen G. Chem. Eur. J. 2008, 14: 6722 - (aa)
Spiess S.Welter C.Franck G.Taquet J.-P.Helmchen G. Angew. Chem. Int. Ed. 2008, 47: 7652 - (ab)
Onodera G.Watabe K.Matsubara M.Oda K.Kezuka S.Takeuchi R. Adv. Synth. Catal. 2008, 350: 2725 - 6a
Fuji K.Kinoshita N.Tanaka K.Kawabata T. Chem. Commun. 1999, 2289 - 6b
Kinoshita N.Marx KH.Tanaka K.Tsubaki K.Kawabata T.Yoshikai N.Nakamura E.Fuji K. J. Org. Chem. 2004, 69: 7960 - 6c
Kanayama T.Yoshida K.Miyabe H.Takemoto Y. Angew. Chem. Int. Ed. 2003, 42: 2054 - 7
Fischer C.Defieber C.Suzuki T.Carreira EM. J. Am. Chem. Soc. 2004, 126: 1628 - 8a
Miyabe H.Matsumura A.Moriyama K.Takemoto Y. Org. Lett. 2004, 6: 4631 - 8b
Miyabe H.Yoshida K.Reddy VK.Takemoto Y. J. Org. Chem. 2009, 74: 305 - For reviews, see:
- 9a
Takeuchi R. Synlett 2002, 1954 - 9b
Miyabe H.Takemoto Y. Synlett 2005, 1641 - 9c
Takeuchi R.Kezuka S. Synthesis 2006, 3349 - 9d
Helmchen G.Dahnz A.Dübon P.Schelwies M.Weihofen R. Chem. Commun. 2007, 675 - For reviews, see:
- 10a
Feringa BL. Acc. Chem. Res. 2000, 33: 346 - 10b
Minnaard AJ.Feringa BL.Lefort L.de Vries JG. Acc. Chem. Res. 2007, 40: 1267 - 11
Liu W.-B.He H.Dai L.-X.You S.-L. Org. Lett. 2008, 10: 1815 - For transition metal catalyzed allylic alkylation of indoles, see:
- 12a
Bandini M.Melloni A.Umani-Ronchi A. Org. Lett. 2004, 6: 3199 - 12b
Bandini M.Melloni A.Piccinelli F.Sinisi R.Tommasi S.Umani-Ronchi A. J. Am. Chem. Soc. 2006, 128: 1424 - 12c
Ma S.Yu S.Peng Z.Guo H. J. Org. Chem. 2006, 71: 9865 - 12d
Trost BM.Quancard J. J. Am. Chem. Soc. 2006, 128: 6314 - 12e
Cheung HY.Yu W.-Y.Lam FL.Au-Yeung TT.-L.Zhou Z.Chan TH.Chan ASC. Org. Lett. 2007, 9: 4295 - 12f
Zaitsev AB.Gruber S.Plüss PA.Pregosin PS.Veiros LF.Wörle M. J. Am. Chem. Soc. 2008, 130: 11604 - 12g
Usui I.Schmidt S.Keller M.Breit B. Org. Lett. 2008, 10: 1207 - 12h
Kagawa N.Malerich JP.Rawal VH. Org. Lett. 2008, 10: 2381 - 13
Krasnov VP.Levit GL.Bukrina IM.Andreeva IN.Sadretdinova LS.Korolyova MA.Kodess MI.Charushin VN.Chupakhin ON. Tetrahedron: Asymmetry 2003, 14: 1985 - 14a
Lu S.-M.Han X.-W.Zhou Y.-G. Adv. Synth. Catal. 2004, 346: 909 - 14b
Lu S.-M.Wang Y.-Q.Han X.-W.Zhou Y.-G. Angew. Chem. Int. Ed. 2006, 45: 2260 - 14c
Zhou Y.-G. Acc. Chem. Res. 2007, 40: 1357 - 14d
Wang Z.-J.Deng G.-J.Li Y.He Y.-M.Tang W.-J.Fan Q.-H. Org. Lett. 2007, 9: 1243 - 14e
Wang X.-B.Zhou Y.-G. J. Org. Chem. 2008, 73: 5640 - 14f
Li Z.-W.Wang T.-L.He Y.-M.Wang Z.-J.Fan Q.-H.Pan J.Xu L.-J. Org. Lett. 2008, 10: 5265 - 14g
Zhou H.Li Z.Wang Z.Wang T.Xu L.He Y.Fan Q.-H.Pan J.Gu L.Chan ASC. Angew. Chem. Int. Ed. 2008, 47: 8464 - 15a
Alexakis A.Rosset S.Allamand J.March S.Guillen F.Benhaim C. Synlett 2001, 1375 - 15b
Naasz R.Arnold LA.Minnaard AJ.Feringa BL. Angew. Chem. Int. Ed. 2001, 40: 927 - 15c
Polet D.Alexakis A. Synthesis 2004, 2586
References
CCDC 722528 contains the supplementary crystallographic data for 9ba. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data request/cif.
Figure 1 Chiral ligands L1, L4, and L-5
Scheme 1 The synthesis of enantiopure (R)-1a
Scheme 2 The synthesis of enantiopure (R)-1b
Scheme 3 The synthesis of ligands L2 and L3
Figure 2 X-ray crystal structure of (S)-9ba (thermal ellipsoids are set at 30% probability)