441313-03-7Relevant articles and documents
A temporary stereocentre approach for the asymmetric synthesis of chiral cyclopropane-carboxaldehydes
Cheeseman, Matt,Davies, Iwan R.,Axe, Phil,Johnson, Andrew L.,Bull, Steven D.
scheme or table, p. 3537 - 3548 (2010/01/06)
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 corresponding syn-aldol products in high de. In the second step, directed cyclopropanation of the alkene functionalities of these syn-aldols occurs under the stereodirecting effect of their 'temporary'β-hydroxyl stereocentres to give a series of cyclopropyl-aldols in high de. Finally, retro-aldol cleavage of the lithium alkoxide of these cyclopropyl-aldols results in destruction of their temporary β-hydroxy stereocentres to afford the parent chiral auxiliary and chiral cyclopropane-carboxaldehydes in >95% ee. The potential of this methodology has been demonstrated for the asymmetric synthesis of the cyclopropane containing natural product cascarillic acid in good yield.
An efficient asymmetric synthesis of cascarillic acid
Cheeseman, Matt,Bull, Steven D.
, p. 1119 - 1121 (2007/10/03)
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 selectivi
