Chemistry of 1,3,5-triaza-2-phosphorinan-4,6-diones: Part XIV. Synthesis of further P-alkyl- and P-aryl-substituted 1,3,5-trimethyl-1,3,5-triaza-2-phosphorinan-4,6-diones

摘要

The reaction of 1,5-bis(trimethylsilyl)-1,3,5-trimethylbiuret with di- and monochlorophosphanes led, with formation of Me3SiCl, to the 1,3,5-trimethyl-1,3,5-triaza-2 sigma(3)lambda(3)-phosphorinan-4,6-diones 1-4 or to the 1,5-bis-(phosphano)-1,3,5-trimethylbiuret derivatives 5 and 6, respectively. Compounds 1, 2 and 4 were characterized by single-crystal X-ray diffraction studies. All the heterocycles were found to display a flattened boat configuration, with the phosphorus atom and the nitrogen atom opposite to it lying out of the plane. Oxidation of the sigma(3)lambda P-3 derivatives with urea/hydrogen peroxide 1:1 adduct furnished the corresponding 2-oxo-2 sigma(4)lambda(5)-phosphorinan-4,6-diones 8-11 and the 1,5-bis(phosphoryl)-biuret derivatives 12 and 13. Spirophosphoranes 15-22 were formed in the reaction of 1-4 with tetrachloro-o-benzoquinone and of 1, 3 and 4 with hexafluoroacetone. Compounds 20 and 21 featured an oxaphosphetane ring, which was stabilized by the electronegative CF3 groups. Compound 22 was formed through the loss of the trimethylsilyl group from 21. With the exception of 21, all oxaphosphetanes were characterized through their H-1, C-13, F-19 and P-31 NMR spectra, and through electron ionization mass spectrometry. For 20, a single-crystal X-ray structure study was conducted. The coordination at phosphorus in 20 was strongly distorted trigonal bipyramidal, with the oxetane ring attached to the phosphorus at one axial and one equatorial position. The reaction of 1 with 1-trifluoromethyl-2-(heptafluoroisopropyl)-biacetyl furnished the adduct 23, rather than an oxaphosphetane such as 20.