sequence that involves a SmI2-promoted stereoselective Reformatsky addition of chiral nonracemic α-bromo α′-sulfinyl ketones to various aldehydes followed by stereoselective reduction of the Reformatsky adduct. The absolute configuration of the products was determined by comparison with literature data and by 1H NMR NOESY experiments. The observed stereoselectivities can be explained in terms of a boat
Polysubstituted Oxygen Heterocycles by a Reformatsky-Type Reaction/Reductive Cyclization Approach from Enantiopure β-Ketosulfoxides
作者:Françoise Colobert、Sabine Choppin、Leticia Ferreiro-Mederos、Michel Obringer、Sandra Luengo Arratta、Antonio Urbano、M. Carmen Carreño
DOI:10.1021/ol701670g
日期:2007.10.1
The stereoselective synthesis of tetrasubstituted tetrahydrofurans and trisubstituted tetrahydropyrans bearing a sulfoxide was achieved by reductive cyclization (Et3SiH/TMSOTf) from the corresponding enantiopure hydroxy ketonesprotected as a dioxolane. These derivatives are easily accessible from a Reformatsky-type reaction between alpha-bromo-alpha'-sulfinyl ketones and protected alpha- or beta-ketoaldehydes