Abstract Three pathways were observed in the reactions of Schiff bases of Thiohydrazides with P(NR2)3. (a) MeS-R2N exchange: MeS-C([dbnd]S)-NHN[dbnd]CHPh (1) reacted with P(NR2)3 led to new Schiff bases, R2N-C([dbnd]S)-NHN[dbnd]CH = Ph (2). (b) Cleavage of C[dbnd]S bond and the formation of P[dbnd]S bond: H2N-C([dbnd]S)-NHN[dbnd]CH = Ph (3) reacted with P(NR2)3 gave rise to the thiophosphoric amide. (Et2N)2P([dbnd]S)-NH-CH = N-N[dbnd]CH-Ph (4). (c) Formation of thiadiazole and triazole: Schiff bases 2a and H2N(MeS)C = N-N[dbnd]CH-Ph (6) reacted with P(NR2)3 respectively and produced 5-dimethyl...
