Dithiols. Part XXVII. Conversion of aliphatic and alicyclic carbonates and thiocarbonates into trithiocarbonates

Abstract

Reaction of the carbonates of ethane-1,2-, propane-1,2-, meso-butane-2,3-, DL-butane-2,3-, and cyclohexane-cis-1,2-diol with sodium (or potassium)O-ethyl xanthate gave the corresponding trithiocarbonates with (when detectable) a net inversion of configuration at one of the carbon atoms concerned; better yields were obtained from thioncarbonates. The carbonate and the thioncarbonate from cyclohexane-trans-1,2-diol reacted by a different mechanism and gave the trans-trithiocarbonate. High yields of trithiocarbonates were obtained, with retention of configuration, from several dithiolcarbonates. Reactions on carbonate, thioncarbonate, and dithiol-carbonate analogues in the trans-decalin system proceeded less readily. The transformations into trithiocarbonates involve various mechanisms, some of which require attack on the carbonyl (or thiocarbonyl) carbon atom; others proceed with attack on the ‘alkyl’ carbon atom of the cyclic ester.

Mass spectral and i.r. parameters for some cyclic thiocarbonates are tabulated, and the significance of the low-frequency bands is discussed.