An Efficient Asymmetric Synthesis of Cascarillic Acid
作者:Steven Bull、Matt Cheeseman
DOI:10.1055/s-2006-939690
日期:——
An efficient six-step asymmetric synthesis of the cyclopropane containing natural product cascarillic acid in 41% overall yield is described. The key synthetic steps involve the use of a temporary stereogenic hydroxyl group to control the facial selectivity of a directed cyclopropanation reaction and its subsequent removal via a retro-aldol reaction.
A temporary stereocentre approach for the asymmetric synthesis of chiral cyclopropane-carboxaldehydes
作者:Matt Cheeseman、Iwan R. Davies、Phil Axe、Andrew L. Johnson、Steven D. Bull
DOI:10.1039/b908600e
日期:——
A novel way of combining chiral auxiliaries and substrate directable reactions is described that employs a three-step sequence of aldol/cyclopropanation/retro-aldol reactions for the asymmetric synthesis of enantiopure cyclopropane-carboxaldehydes. In the first step, reaction of the boron enolate of (S)-N-propionyl-5,5-dimethyl-oxazolidin-2-one with a series of α,β-unsaturated aldehydes affords their