Stereoselective opening of chiral α-stannylacetals with organometallic reagents
摘要:
Alpha-Tributylstannylacetals derived from 2R,3R-tartramide or 2R,4R-pentanediol have been treated with various organometallic reagents to give chiral alpha-oxygenated organotins. Relatively poor diastereoselectivities were obtained with organoaluminium reagents, but reactions involving RCu or R2CuLi in the presence of boron trifluoride etherate or allyltributyltin in the presence of TiCl2, (OiPr)2 gave the desired compounds with diastereoselectivities of > 80/20