Synthesis of enantioenriched. alpha.-hydroxy-. alpha.-allenylacetic acids by [2, 3] Wittig rearrangement of. alpha.-(propargyloxy) acetates
JA Marshall, XJ Wang
Index: Marshall, James A.; Wang, Xiao-jun Journal of Organic Chemistry, 1991 , vol. 56, # 16 p. 4913 - 4918
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Citation Number: 86
Abstract
Optically active (R)-(propargy1oxy) acetic esters 5, available in ca. 90% ee through reduction of alkynones 2 with Chirald-LiAlH4 followed by alkylation with chloroacetic acid and esterification with CHSNZ, undergo highly stereoselective [2, 3] rearrangement upon treatment with LDA in THF at-78 OC followed by CpzZrC19 to afford a (s)-hydroxy-B (R)- allenic eetsrs 7 with complete transfer of chirality and> 90% diaatereoeelectivity. Upon ...
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