Abstract: The addition reaction of 5-hydro-1, 9-dioxa-4 , 6-diaza-5-phosphaspiro-[4, 4]-nonane 1 with carbon disulfide or isothiocyanates is accompanied by a rearrangement to produce 2-mercaptothia-zoline 2, and 2-substituted aminothiazolines 4 respectively. The mechanism of reaction may involve the addition of 1 and its tautomer 6 to the unsaturated bond.

Key words: Phosphorane compound, Isothiocyanates, Thiazolines