Synthesis of 1,3,5,2λ 5 ‐Triazaphosphinines by Intramolecular Cyclisation of ( N ‐Cyanophosphorimidoyl)guanidines and Diguanidinophosphonium Chlorides

The sodium phosphonium diylide Na[Ph 2 P(NCN) 2 ] ( 3 ) − the first example of a stabilised phosphonium diylide − was synthesised by treatment of sodium diphenylphosphide with 2 equiv. of cyanic azide. Compound 3 reacted with alkyl‐ and arylammonium salts [RR′NH 2 ]Cl {R = PhCH 2 , t Bu, Ph; R′ = H; RR′ = −[(CH 2 ) 2 O(CH 2 ) 2 ]−}. Depending on the molar ratios (1:1 or 1:2), ( N ‐cyano‐ P , P ‐diphenylphosphorimidoyl)guanidines Ph 2 P(NCN)N=C(NH 2 )NRR′ ( 8 ) or diguanidinodiphenylphosphonium chlorides [Ph 2 P{N=C(NH 2 )NRR′} 2 ]Cl ( 10 ) were formed. When molten, compounds 8 yielded new cyclic 1,3,5,2λ 5 ‐triazaphosphinines 11 . The fusion of compound 10 allowed the formation of the same 1,3,5,2λ 5 ‐triazaphosphinines 11 , along with the formation of NH 4 Cl or [PhNH 3 ]Cl. A crystal structure analysis of 4‐amino‐6‐morpholino‐2,2‐diphenyl‐1,3,5,2λ 5 ‐triazaphosphinine ( 11a ) revealed an almost planar six‐membered ring for the 1,3,5,2λ 5 ‐triazaphosphinine template. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)