Abstract
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The lithium salt of racemic S-benzyl-N-t- butyldiphenylsilyl-S-methylsulfoximine (2) undergoes 1, 2-addition to imines that have been activated by precomplexation with boron trifluoride diethyl etherate (BF3.Et2O), and aldehydes, with high diastereoselectivity. The relative lS*, 2S.*, S*s stereochemistry of the major diastereomeric adducts of (2) and EtCH = NPh and PriCH = NPh, and the relative lS*, 2S*, S*s stereochemistry of the major diastereomeric adduct of (2) and propanal were unequivocally determined by single-crystal X-ray structure analysis. An open transition state has been proposed to account for the stereochemical outcome of these reactions. © 1992 ASEG.