Cyclohexanone and cyclopentanone react with 2,4 - bis - 4 - methoxyphenyl) - 1,3,2,4 - dithiadiphosphetane 2,4-disulfide (lawesson Reagent (LR) at 80° with formation of new spiro - 1,3,5,2 - trithiaphosphorines 1 and 2, respectively. 2-Methyl and 2-phenylcyclohexanone also react with LR at 80° producing the enethiols 3 and 4, which on storage are transformed into the sulfides 5 and 6. Unsaturated cyclohexanones