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DOI: 10.1055/s-0028-1087286
Synthesis of (+)-Meloscine
Contributor(s):Philip Kocienski, Zofia KomstaTechnische Universität München, Garching, Germany
Enantioselective Total Synthesis of the Melodinus Alkaloid (+)-Meloscine
Angew. Chem. Int. Ed. 2008, 47: 5082-5084
Publication History
Publication Date:
20 November 2008 (online)
Key words
meloscine - asymmetric [2+2] cycloaddition - ring expansion - Claisen rearrangement
Significance
(+)-Meloscine is one of the alkaloids isolated from certain plants from Apocynacea species, used in Chinese folk medicine. The synthesis highlights construction of the cyclobutane ring in D via a regio- and stereoselective template-controlled [2+2] cycloaddition. The dr of the cycloaddition was not reported.
Comment
The photocycloaddition of A and B in the presence of a chiral complexing agent C gave D in good yield. Treatment of the allylic alcohol H with MeC(OMe)3 resulted in Claisen rearrangement and gave a 2.3:1 mixture of diastereoisomers. The minor, unwanted isomer was removed after Boc deprotection.