REACTIONS OF SILIRANES WITH ELEMENTAL SULFUR AND WITH TERT-BUTYL MERCAPTAN - PREPARATION OF THE 2,3-DITHIA-1-SILACYCLOPENTANE RING-SYSTEM

The reaction of 1,1-dimethyl-trans-2,3,-bis(2′,2′-dimethylcyclopropylidene)-1-silirane with S8 gives a mixture of four isomeric products derived from incorporation of one sulfur atom and a cyclopropylcarbinyl-to-butenyl type rearrangement. This silirane reacts with t-butyl mercaptan to give a product of mercaptan addition in which a cyclopropylcarbinyl-to-butenyl rearrangement also has occurred. Hexamethylsilirane reacts with S8 to give 1,1,4,4,5,5-hexamethyl-2,3-dithia-1-silacyclopentane in high yield. These reactions are discussed in terms of free radical mechanisms. © 1979.