Some contributions to regio and stereo control: from Cincholoipon and Cantharidin to the present.

Abstract

A condensed review of some of the major original contributions of the author's research group to organic synthesis during more than half a century. The emphasis is on methodology, especially as it involves the control of regio- and stereochemistry. The application of these methods in the total synthesis of specific natural products in the author's laboratory is not discussed in extenso, but only by focusing on certain key steps which illustrate the application of the methods mentioned here. Methods discussed in this fashion are: cationic polyene cyclizations; the enamine alkylation and acylation of ketones and aldehydes; the metalloenamine alkylation; the regiospecific formation and trapping of enolates, via electron addition or via conjugate addition of organometallic reagents to enones; regiospecific enolate formation-trapping from saturated ketones and from beta-alkoxy enones; the epoxynitrile and the allylic epoxynitrile cyclizations; the cyclization of olefinic diazoketones; the cyclization of alkynyl ketones; protected cyanohydrins as acylcarbanion equivalents; the vinyl radical cyclization; the control of regio- and stereochemistry via radical cyclization to temporary rings.