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Total Syntheses of Cladoacetals A and B: Confirmation of Absolute Configurations

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posted on 20.07.2012, 00:00 by Day-Shin Hsu, Shih-Chung Lin
The first enantioselective syntheses of cladoacetals A (1a, overall yield: 16%) and B (1b, overall yield: 34%) from crotonaldehyde in nine and seven steps, respectively, have been accomplished. Sharpless asymmetric dihydroxylation, Suzuki coupling, and acid-catalyzed intramolecular acetalization were the key steps in the syntheses. The absolute configuration of natural (+)-cladoacetal A was affirmed to be 1S,3S,4R, whereas that of (−)-cladoacetal B was affirmed to be 1R,3S,4S.