Intramolecular amine-induced [1,3]-sigmatropic rearrangement in the reactions of aminophosphinites or phosphites with elemental sulfur or selenium

Abstract

Ether- and thioether-functionalized cyclodiphosphazanes cis-[(BuNP)-Bu-t(OCH2CH2EMe)](2) (E = O, 1; E = S, 2) react with 2 equiv of elemental sulfur or selenium to produce dichalcogenides cis-[(BuNP)-Bu-t(E)(OCH2CH2EMe)]2 (4-6), whereas the similar reaction of amine-functionalized cyclodiphosphazane cis-[(BuNP)-Bu-t(OCH2CH2NMe2)](2) (3) with elemental chalcogen results in the formation of thio- or selenophosphates trans-[(BuNP)-Bu-t(O)(ECH2CH2NMe2)](2) (E = S, 7; E = Se, 8) through [1,3]-sigmatropic rearrangement. The X-ray crystal structure of 8 confirms the rearranged product as the trans isomer with a planar P2N2 ring. The equimolar reaction of P(OCH2CH2OMe)(3) (9) with elemental sulfur or selenium produces the simple sulfide and selenide E=P(OCH2CH2OMe)(3) (E = S, 11; E = Se, 12) derivatives, respectively. In contrast, the reaction between P(OCH2CH2NMe2)(3) (10) and S or Se furnishes the rearranged products (13 and 14). The rearrangement reaction was monitored by (PNMR)-P-31 spectroscopy, which confirms the formation of selenophosphinic acid as the first step of the rearrangement. The [1,3]-sigmatropic rearrangement presumably takes place through chalcogen-nitrogen interactions.