Reaction of salicylalkylenediimines with 2-chloro-4,5-diphenyl-1,3,2-dioxaphospholene

Abstract

The structure of compounds IIIa–IIIc was proved by the IR, Н, and Р NMR spectroscopy, mass spectrometry, and composition, by the elemental analysis data. The IR spectra of the products IIIa–IIIc contain absorption bands at 1623–1627 (С=N) and 2590–2724 cm (broadened complex band, NH2). The chemical shift of the phosphorus atom at δP from –114 to –122 ppm is characteristic of the hexacoordinated phosphorus derivatives. Notice that the P NMR spectra of the reaction mixtures of IIIa–IIIc contain signals indicative of the formation of diastereoisomers mixture. As a result of fractional crystallization compound IIIa was obtained as the two diastereoisomers mixture in the ratio 1:1. Compounds IIIb and IIIc were isolated as individual diastereomers. Due to their salt structure the Н NMR spectra of compounds IIIa– IIIc contain poorly resolved signals, therefore only group analysis of the proton signals was performed on the basis of chemical shifts without considering the fine structure of the spectra. The transannular N→P bond (2.006–2.007 A) is realized in the compounds IIIa–IIIc. The intermolecular bonding of similar type was earlier observed in the series of pentacoordinated phosphorus derivatives [1–5]. On treating with triethylamine, the product IIIa undergoes dehydrochlorination to give phosphorate IVa of neutral structure (δР –105.87 ppm).