Chiral Acylsilanes in Organic Synthesis. Diastereoselective 1,2 Additions to Racemic Alkoxymethyl-Substituted Acylsilanes

Article abstract of DOI:10.1002/hlca.19910740712

The synthesis of the three alkoxymethyl-sustituted acylsilanes 1-3 is described (Schemes 1 and 2).Their reactions with NaBH4 as well as PhLi gave the corresponding alcohols with moderate to good diastereoisomeric induction (up to 78percent de; see Table), depending upon the solvent used (Scheme 3).The results indicate that in Et2O, the reactions with PhLi proceed via 6-membered chelates (see C in Scheme 4) leading to the products with high de's (74 - 78percent).In THF, these chelates are not formed, and as a consequence, the additions take place with reversed and lower stereoselectivities (34 - 50percent de).