Synthesis of Linear and Cyclic Carbophosphazenes via an Oxidative Chlorination Strategy

Abstract

The use of a mild, oxidative chlorination route for the synthesis of linear and cyclic carbophosphazenes is described. For example, chlorination of the linear PNCN chain Ph(2)P-N=C(Ph)-N(SiMe(3))(2) (1) with C(2)Cl(6) led to the clean formation of the previously known 8- and 6-membered rings [Ph(2)PNC(Ph)N](2) (2) and [Ph(2)PNC(Ph)NP(Ph)(2)N] (3), respectively. In a similar fashion, the N-alkyl-substituted PNCN derivatives, Ph(2)P-N=C(Ph)-N((t)Bu)SiMe(3) (4) and Ph(2)P-N=C(Ph)-N(i)Pr(2) (7) were readily converted by C(2)Cl(6) into the halogenated derivatives ClPh(2)P=N-C(Ph)=N(t)Bu (5) and [ClPh(2)P=N=C(Ph)-N(i)Pr(2)]Cl (8), respectively. Protonation of 5 was accomplished using HCl and gave the carbophosphazenium salt [ClPh(2)P=N-C(Ph)=N((t)Bu)H]Cl (6). In addition, the isolation of a rare 8-membered P(2)N(4)C(2) heterocycle [(Cl(3)P=N)ClPNC(Ph)NP(Cl)(2)NC(Ph)N] (9) from the reaction of PCl(5) and Li[PhC(NSiMe(3))(2)] is reported. Treatment of 9 with one equivalent of GaCl(3) led to the discovery of an unusual Lewis acid-induced ring contraction reaction whereby the (PNCN)(2) ring in 9 is converted into the novel 6-membered P(2)N(3)C heterocyclic adduct [(Cl(3)P=N)ClPNP(Cl)(2)NC(Ph)N].GaCl(3) (10) with concomitant release of PhCN. Structural characterization of compounds 1, 5, 6, and 8-10 by single-crystal X-ray diffraction is also provided.

A Triazadiphosphole

“…[23] Because of the astonishing stability of 2 and 3 in solution as Scheme 2. Binary P-N five-membered rings with P III atoms.…”

Reperfusion strategies in the management of extremity vascular injury with ischaemia

“…In conclusion, we present here an easy, high‐yielding (>95 %) synthetic procedure and full characterization (see the Supporting Information) of the first triazadiphosphole stabilized as a GaCl 3 mono‐ and diadduct 7a–d. Moreover, 2 and 3 are rare examples of structurally characterized Lewis acid–base adducts involving a ring atom within a PN ring 23. Because of the astonishing stability of 2 and 3 in solution as well as in solid, both compounds may have great synthetic potential, for example, as sources for binary PN or ternary PNGa species.…”

The Chemistry of Cyclic Carbaphosphazenes: The First Observation of (R2PN)(ClCN)2 (R═Cl, Ph) as a Reagent for the Conversion of Alcohols to Aldehydes, Ketones, and Alkyl Chlorides

“…11 New examples of carbaphosphazenes and better methods for their synthesis have also been reported recently. 12 In this article we report the first observation of the use of chlorinated carbaphosphazenes as a reagent along with dimethylsulfoxide for the mild oxidation of alcohols to aldehydes and ketones. We also report herein the conversion of alcohols to alkyl chlorides when DMF is used instead of DMSO along with the carbaphosphazene.…”