Introduction of the (−)-Berkelic Acid Side Chain and Assignment of the C-22 Stereochemistry

X Wu, J Zhou, BB Snider

Index: Wu, Xiaoxing; Zhou, Jingye; Snider, Barry B. Journal of Organic Chemistry, 2009 , vol. 74, # 16 p. 6245 - 6252

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Citation Number: 17

Abstract

A Kiyooka aldol condensation of an aldehyde with a trimethylsilyl ketene acetal and the oxazaborolidinone prepared from N-Ts-(S)-valine gives two of the four possible aldol adducts, which were oxidized and deprotected to complete the synthesis of (−)-berkelic acid and (−)-22-epi-berkelic acid. This synthesis establishes the absolute stereochemistry and assigns the stereochemistry at C-22. A biosynthetic pathway is proposed that is consistent ...