Y-Hydroxyphosphine oxides

The stereospecific olefination method involving synthesis, separation, and base-catalysed, decomposition of diastereomeric P-hydroxyalkylphosphine oxides has been used for the preparation of pure isomers of y,S-unsaturated acetals (Scheme 11). The same principle has been extended to trisubstituted alkenes. The yields are generally still good, but the diastereomeric hydroxyphosphine oxides involved are less stable in some cases and the routes to them are less stereoselective. However, the method works reasonably well for the synthesis of ( )-and (Z)-allylic amines (Scheme 12). Unfortunately, (2-substituted-2-amino)-... 

A soln. of startg. phosphine imine in THF added dropwise to /-PrjNLi in the same solvent at —30° under argon, the mixture stirred for 1 h, cooled to —70°, treated dropwise with benzaldehyde in THF, then allowed to warm to room temp. - erythro-product. Y 86%. F.e., electrophiles, and conversion to p-hydroxyphosphine oxides, s. J. Barluenga et al.. Synthesis 1988, 562-4. 

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