Convolutamydine A: the first authenticated absolute configuration and enantioselective synthesis

The absolute configuration of (+)-convolutamydine A 1 isolated from Amathia convoluta has been unambiguously established as (R) by enantioselective synthesis, based on chiral auxiliary-directed π-face discrimination in an allyl metal addition to (1R,2S,5R)-8-phenylmenthyl ester 7. For an independent and unequivocal proof, the absolute stereochemistry of synthetic precursor 11 en route to 1 was determined by X-ray crystallography.

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(3R)-4,6-Dibromo-3-hydroxy-3-(2-oxopropyl)-1,3-dihydroindol-2-one ((+)-convolutamydine A)C11H9Br2NO3[α]D20=+48.2 (c 0.20, MeOH)Source of chirality: (−)-(1R,2S,5R)-8-phenylmentholAbsolute configuration: (3R)