Total Synthesis and Stereochemical Reassignment of Citrafungin A
Zongjia Chen, Angus Robertson, Jonathan M White, Mark A Rizzacasa
ORGANIC LETTERS | AMER CHEMICAL SOC | Published : 2019
The stereoselective 12-step total synthesis of the reassigned structure for citrafungin A (1a) via cyclobutene diester 10 is described. Key steps involved a formal [2 + 2]-cycloaddition, oxa-Michael/cyclobutanone ring-opening cascade to secure the alkyl citrate core, and asymmetric vinylzinc addition to form the C6 stereocenter. In addition, no oxidative adjustments are required to secure the citrate oxidation level.
We thank the Australian Research Council Discovery Grants Scheme and the University of Melbourne Research Grants Support Scheme for funding. We also thank Dr. Christian Gunawan and Tony Duncan (Circa Pty Ltd.) for the generous gift of (S)-(+)-gamma-hydroxymethyl-gamma-butyrolactone.