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Synfacts 2017; 13(11): 1128
DOI: 10.1055/s-0036-1591617
Synthesis of Heterocycles
© Georg Thieme Verlag Stuttgart · New York

Synthesis of Pyrrolocoumarins and Substituted Pyrroles

Contributor(s):
Victor Snieckus
,
Marzieh Miranzadeh (Snieckus Innovations and Tarbiat Modares University, Tehran, Iran)
Reddy EP. Sumankumar A. Sridhar B. Hemasri Y. Rao YJ. * Reddy BV. S. * CSIR-Indian Institute of Chemical Technology, Hyderabad, Osmania University, Hyderabad and Telangana University, Nizamabad, India
1,5-Electrocyclization of Conjugated Azomethine Ylides Derived from 3-Formyl Chromene and N-Alkyl Amino Acids/Esters.

Org. Biomol. Chem. 2017;
15: 7580-7583
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Further Information

Publication History

Publication Date:
19 October 2017 (online)

 
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Key words

chromenopyrrolones - chromenecarbox-aldehydes - alkyl amino esters - 1,5-electro-cyclization - azomethine ylides

Significance

Reported is a synthesis of chromeno[3,4-b]pyrrol-4(3H)-ones 3 and substituted pyrroles 5 by using chromene-3-carboxaldehydes 1 and N-alkyl amino acids/esters (4/2) as starting materials. These reactions are postulated to occur through 1,5-electrocyclization of the conjugated azomethine ylides 6. Compounds 1 (R1 = EDG) afforded good yields of products 3 and 5. Compounds 2 (R4 = Ar, Alk) gave products 3 in good yields.


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Comment

Pyrrolocoumarins are found in a variety of natural products and are significant in the pharmaceutical field (S. S. Soman et al. Chem. Heterocycl. Compd. 2011, 46, 1514). Some chromeno[3,4-b]pyrrol-4(3H)-ones, i.e. the marine alkaloids, exhibit HIV-1 integrase inhibition, immunomodulatory activity, or cytotoxicity (P. Langer and co-workers Tetrahedron Lett. 2010, 51, 3897). The current work represents a synthesis of pyrrolocoumarins from chromenecarboxaldehydes without any catalyst, whereas in other work, aminocoumarins and arylglyoxal monohydrates have been converted into chromeno[3,4-b]pyrrol-4(3H)-ones by using PTSA as a catalyst (X. Yang et al. Eur. J. Org. Chem. 2017, 2258). The reaction involves the use of a coumarin ring to construct a pyrrole, based partially on the propensity of the phenolate ion to act as a leaving group.


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