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

Ether- and thioether-functionalized cyclodiphosphazanes cis-tBuNP(OCH2CH2EMe)]2 (E = O, 1; E = S, 2) react with 2 equiv of elemental sulfur or selenium to produce dichalcogenides cis-tBuNP(E)(OCH2CH2EMe)]2 (4-6), whereas the similar reaction of amine-functionalized cyclodiphosphazane cis-tBuNP(OCH2CH2NMe2)]2 (3) with elemental chalcogen results in the formation of thio- or selenophosphates trans-tBuNP(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 (31)PNMR 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.