Tetrahedron: Asymmetry

Asymmetric conjugate additions to 1, 1′-diactivated cyclic enones—A comparative study

X Tang, AJ Blake, W Lewis, S Woodward

Index: Tang, Xiaoping; Blake, Alexander J.; Lewis, William; Woodward, Simon Tetrahedron Asymmetry, 2009 , vol. 20, # 16 p. 1881 - 1891

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Citation Number: 27

Abstract

A study of copper-phosphoramidite-catalysed ZnR2 and AlR3 additions to 1, 1′-dicarbonyl- activated cyclic Michael acceptors has revealed high enantioselectivities for AlR3 (R= Me, Et) 1, 4-addition to a range of 3-acylcoumarins (85–98% ee, trans: cis∼ 90: 10) using commercial or readily available ligands. Large substituents at the 6-position, and to some extent at the 5-position, of the coumarin are less well tolerated, nor is truncation of the ...