REGIO- AND STEREOSELECTIVE ALCOHOLYSIS OF (R)-STYRENE OXIDE WITH BIS-TRIBUTYLTIN OXIDE AND BIS-CHLORODIBUTIYLTIN OXIDE

CLAUDIO SALOMON; LABORDE M.; GONZALEZ SIERRA M; MASCARETTI A.

MAIN GROUP METAL CHEMISTRY

FREUND PUBLISHING HOUSE LTD

Lugar: Tel Aviv; Año: 1998 vol. 10 p. 617 - 622

0334-7575

We report herein a convenient method for the regio- and stereoselective ringopening of (R)-styrene oxide (1) by means of primary and secondary alcohols, using bis-tributyltin oxide (2) and bis-chlorodibutyltin oxide (3) as Lewis acids, in catalytic or in stoichiometric amount. The alcoholysis of (fl)-styrene oxide has been found to proceed with very good regio- and stereoselectivity affording the corresponding 2-alcoxy-2-phenylethanol. Alcohols attacks at the benzylic position almost exclusively. Introduction Chiral aryl substituted oxiranes are among the most useful chiral building blocks for the asymmetric synthesis of several types of bifunctional compounds,´ in particular for the synthesis of enantiomerically pure Ã?-alkoxy alcohols. The regio- and stereocontrolled addition of suitable alcohols to 1,2-epoxides can, in theory, be helpful for the stereoselective synthesis of several therapeutic agents and natural products. 2 These transformations are generally promoted by different types of Lewis acid, which induce the nucleophilic attack over the position that can best accommodate the positive charge.3 However, the yields are not always satisfactory and stronger reaction conditions promote extensive polymerization. 4 Organotin reagents have been used for the regiospecific conversion of oxiranes into 1,2amino-2 1,2-halo-3, 1,2-phenoxy-3 and 1,2-azido alcohols.4 Organotin phosphate condensates 5 promoted the methanolysis of (R)-styrene oxide (1)