Reported Asymmetric Synthesis of Santonin

Abstract

THE announcement that santonin containing approximately 93 per cent of the lævo-rotatory variety (naturally occurring santonin is lævo-rotatory) has been obtained by Paranjape, Phalnikar, Bhide and Nargund¹ during the synthesis of santonin without apparently any asymmetric influence at any stage of the synthesis is of unusual interest. The realization of such a result cannot be excluded on the evidence given. On the other hand, it is contrary to all analogous experimental results so far recorded that methylation of an externally compensated and optically inactive compound should proceed at different rates on the lævo- and dextro-constituents of the externally compensated substance even when the asymmetric carbon atom is involved. It is possible, however, to conceive cases when a difference in reaction velocities of the lævo- and dextro- varieties of an externally compensated compound may be realized.