The chiral N-methyl'-(1-phenylethyl)-substituted anthranilamides R-(+)-3 (R C -enantiomer) and S-(-)-3 (S C +nantiomer) were formed by reaction of N-methylisatoic anhydride, 1, with R-(+)-and S-(-)-1-phenylethylamine, R-(+)-2 and S-(-)-2. Reaction of R-(+)-3 and S-(-)-3 with phosphorus trichloride led to mixtures of diastereomers of 5.6-benzo-2-chloro-l-methyl-3-(1-phenylethyl)-1, 3, 2[sgrave]3γ3-diazaphosphorin-4-ones, (R C , S P )-4/(R C , R P )-4 and (S C , R P )-4/(S C , S P )-4. Attempted separation of the diastereomers of 4 by several methods failed. Reaction of the mixtures of (R C , S P )-4/(R C , R P )-4 and (R C , S P )-4/(S C , S P ),-4 with bis-(2-chloroethyl)amine hydrochloride in the presence of uiethylamine again led to mixtures of diastereomers of 5.6-benzo-2-[bis-(2-chloroethyl)amino]-1-methyl-3-(l-phenylethyl)-l, 3, 2[sgrave]3γ3-diazaphosphorin-4-one, (R C , S P )-5/(R C , R P )-5 and (S C , R P )-5/ (S C , S P )-5. By recrystallization it was possible to isolate the pure diastereomers (R C , S P )-5 and (S C , R P )-5. Oxidation reactions on (R C , S P )-5 and (S C , R P )-5 by the hydrogen peroxide-urea 1:1-adduct ((NH2)2C(:O).H2O2) or elemental sulfur led to the formation of the corresponding 2-oxo- and 2-thio-substituted 5, 6-benzo-1, 3, 2[sgrave]4γ5-diazaphosphorin-4-ones, (R C , R P )-6, (S C , S Pp )-6, (R C , R P )-7 and (S C , S P )-7 as pure diastereomers in each case. All compounds were characterized unambiguously by n.m.r.-spectroscopy, mass spectrometry and elemental analysis. Optical rotations were determined for most of the reaction products described. For compounds (R C , S P )-S, (R C , R P )-6, (S C , S P )-6 and (R C , R P )-7, X-ray crystal structure analyses were conducted. In all cases the absolute configuration at phosphorus was determined. The enantiomers of 6 crystallize in different space groups because only the (R C , R P ) form contains solvent of crystallization.
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