Neue Phospholen‐ und Phosphepin‐Derivate aus λ 3 ‐Phosphorverbindungen und Hexafluoraceton oder perfluorierten α‐Diketonen

New Phospholene and Phosphepine Derivatives from λ 3 ‐Phosphorus Compounds and Hexafluoroacetone or Perfluorinated α‐Diketones The reaction of the bis(2‐chloroethyl)amino‐substituted benzoxazaphosphorinone 1 with hexafluoroacetone (HFA) proceeds with insertion of the carbonyl group of HFA into the heterocycle of 1 to form the oxazaphosphepinedione 2 . Triethyl phosphite ( 3 ) and triphenyl phosphite ( 4 ) react with the perfluorinated diketones 5 and 6 with formation of the pentaoxyphosphoranes 7–10 containing a dioxaphospholene ring system. The reaction of the (2‐chloroethyl)amino‐ and bis(2‐chloroethyl)amino‐substituted 1,3,5,2‐triazaphosphorinanediones 11–14 with the perfluorinated diketone C 2 F 5 C(:O)C(:O)CF 3 ( 15 ) furnishes spirophosphorane derivatives with the dioxaphospholene ring system, 16 and 17 , in two cases only. Compound 1 and 2‐[bis(2‐chloroethyl)‐amino]‐4 H ‐1,3,2‐benzodioxaphosphorin‐4‐one ( 18 ) react with the perfluorinated α‐diketones 5 and 6 with insertion of the diketones into the heterocycle of 1 and 18 with formation of compounds 19–22 containing dioxa‐ and oxazaphosphepinone ring systems. The expected oxidative addition of the diketones to λ 3 P with formation of spirophosphoranes was not observed. Compounds 19–22 were obtained as mixtures of isomers ( 19a/b–22a/b ). Single crystal X‐ray structure analyses were conducted on 2 and 9 . The seven‐membered ring of 2 displays a “tub” conformation, with the O and benzo C atoms lying out of the plane of the other four atoms. The two independent molecules of 9 are similar, but differ in the degree of distortion from trigonal‐bipyramidal geometry of phosphorus.