Isoxazolines phosphorylated

The reactions of isoxazolin-5-ones (1379) with 1 mol of phosphoryl chloride and DMF in boiling chloroform for 1.5 hr afforded 1,3-oxazin-6-ones (1381) in 69-74% yields via aminomethylenemalonate derivatives (1380) (87JOC3426). If 2 mols of Vilsmeier-Haack reagent were used in boiling carbon tetrachloride for 2 hr, then 1381 (R = H) and the amino-methylenemalonamate derivative (1382) were obtained in 8% and 76% yields, respectively, from 1379 (R = H). 

When 3,4-disubstituted 4-aminoisoxazolin-5(4Af)-ones (9) are hydrogenated, and then subsequently recyclized, high yields of imidazoles (10) are obtained (Scheme 6.1.4). The starting materials can be readily made from isoxazolin-5(4Af)-ones by sequential bromination, reaction with sodium azide and conversion of azide into amino by reaction with hydrobromic acid in acetic acid. The amines are then converted into formamidine or acetamidine derivatives with DMF or dimethylacetamide under reflux in phosphoryl chloride-chloroform. Yields at this stage are 50-93%. Catalytic... 

In the presence of BuLi in thf, the active methylene compounds (Et0)2P(0)CH2Z (Z = P03Et2, COOMe, S02Me or CN) add to PhCH—CMe(N02) to give the products 78 as intermediates in a synthesis of C-phosphorylated 2-isoxazoline derivatives Other reactions have been performed between 2-aryl-1-nitroethenes and the anions from dimethyl methylphosphonate " or dimethyl (difluoromethyl)phosphonate in the initial steps towards syntheses of phaclofen 80 X = H) and its difluoro analogue (80 X = F) by the reduction (H2-Raney nickel) of the initial adduct 79 (Scheme 6). 

The cycloaddition of an arylnitrile oxide to methyl ethynylmethylphosphinate in an inert solvent at 5 °C produces a (5) -phosphinoylated-isoxazole 513 in high yield " and phosphorylated 1,2,4-oxadiazoles 514 are obtainable in a similar addition to (R0)2P(Z)CN (Z = O or Phosphorylated nitrile oxides, e.g. 515, are generally prepared by the Et3N-dehydrobromination of the product from the bromination of the oxime of a j5-(dialkoxyphosphinoyl)acetaldehyde, and then used in situ in reactions with alkenes to give isoxazolines and with alkynes to give isoxazoles . The chlorination and subsequent dehydrochlorination of diethyl (nitromethyl)phosphonate yield the nitrile oxides 516 (R = EtO Pr O or morpholinyf and these, with unsaturated centres, yield isomerically phosphorylated isoxazolines and isoxazoles. 

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