Derivate der 5,6-benzo-1,3-dialkyl-2-oxo-1,3,2 λ4-diazaphosphorinan-4-one: Umsetzung mit ketonen (hexafluoraceton und trifluoracetophenon); Einkristall-röntgenstrukturanalysen von konstitutionsisomeren

Abstract

5,6-Benzo-1-methyl-3-(2-chloroethyl)-2-hydro-2-oxo-1,3,2 λ 4-diazaphosphorinan-4-one ( 2) reacts with p-benzoquinone in a 1:1 molar ratio in the presence of triethylamine as a catalyst to give as the sole addition product 5,6-benzo-1-methyl-3-(2-chloroethyl)-2-(2,5-dihydroxyphenyl)-2-oxo-1,3,2 λ 4-diazaphosphorinan-4-one ( 3). No reaction occurred betwwen 2 and acetone, methyl t-butylketone or acetophenone in the presence of triethylamine, even at elevated temperature. The reaction of the 5,6-benzo-1,3-diorgano-2-hydro-2-oxo-1,3,2 λ 4-diazaphosphorinan-4-ones 1 and 2 with hexafluoroacetone furnished the 2-hexafluoroisoproposy-substituted compounds 4a and 5a. In both cases, the 2-bis(trifluoromethyl)hydroxymethyl-substituted structural isomers 4b and 5b were formed in low yield. Analogous reactions of 1 and 2 with trifluoroacetophenone, catalysed by triethylamine, furnished as the main products the 2-trifluoromethylphenylmethoxy-substituted compounds 6a and 7a, together with small amounts of the 2-trifluoromethylphenylhydroxymethyl-substituted isomers 6b and 7b. The unusual reaction of the acetylaminophosphorinanone 8 with hexafluoroacetone in a 1:2 molar ratio led to the formation of the 2-hexafluoroisopropoxy-substituted compound 4a with N-acetyl-bis(trifluoromethyl)imine ( 11) as a by-product. A pathway for the formation of 4a is proposed. Characterization of 3 and 4a–7a was based on 1H, 13C, 19F and 31P NMR and mass spectra. The existence of 4a, 5a, 4b and 5b as enantiomeric pairs was established mainly by 19F NMR spectroscopy. The diasteromeric pairs 6a and 7a, 6b and 7b were not observed in the 19F and 31P NMR spectra. X-ray structure analyses were carried out for 4a, 5b and 7a. Compound 7a crystallizes with two independent molecules, which are however closely similar. Intermolecular hydrogen bonds of the form P(:O)…H are observed for all compounds, leading to centrosymmetrical dimers. In 4a the two trifluoromethyl substituents presumably make the carbon H atom more positive. The existence of hydrogen bonds is confirmed by infrared spectroscopic studies. In all structures the phosphorus atom exhibits a distorted tetrahedral coordination. The six-membered heterocycle of 4a displays an envelope conformation with the phosphorus atom out of plane.