... Tetrahedron Letters. Volume 28, Issue 48, 1987, Pages 5973–5976. Cover image Cover image. Functionalized cyclopentanes via radical cyclizations using thiocarbonate derivatives as initiators and terminators. ... 8118 USA. Received 25 August 1987, Available online 9 March 2001. Abstract. A radical-based cyclization is described that employs xanthates or cyclic thionocarbonates as initiators and allylic dithiocarbonates or allylic thiocarbamates as terminators. ...