CHIRAL ACYLSILANES IN ORGANIC-SYNTHESIS .2. THE ROLE OF THE SOLVENT, THE ORGANOMETALLIC REAGENT, AND THE NATURE OF THE SUBSTRATE FOR THE DIASTEREOSELECTIVITY OF 1,2-ADDITIONS TO RACEMIC ALKOXYMETHYL-SUBSTITUTED ACYLSILANES

The role of the solvent, the organometallic reagent, and the nature of the substrate for the diastereoselectivity of 1,2-additions to racemi c alkoxymethyl-substituted acylsilanes was investigated with the acyls ilanes 1a-d by variation of the reaction parameters. The results obtai ned in this study support strongly the previously proposed preferred ' chelate-controlled' reaction path followed under several reaction cond itions: highest stereoselectivities were obtained with the best chelat ing substrates reacting with the most Lewis-acidic organometallic reag ents in the least donating solvents. It is shown that almost complete stereoselectivity can be obtained using optimal reaction conditions.