Diisopropyl phosphite

The reactions of sodium dimethyl and diisopropyl phosphite with 4-nitrobenzyl chloride, 9-chlorofluorene, and diphenylchloromethane provided information that supported the proposed reaction mechanism. The RaPO anion acts towards an arylmethyl chloride as a base and abstracts a proton to form a carbanion, which can then participate in single-electron transfer processes to produce carbon-centred radicals. ... 

Akiyama et al. disclosed an asymmetric hydrophosphonylation in 2005 (Scheme 32) [55], Addition of diisopropyl phosphite (85a) to A-arylated aldimines 86 in the presence of BINOL phosphate (R)-M (10 mol%, R = 3,5-(CF3)j-C Hj) afforded a-amino phosphonates 87 in good yields (72-97%). The enantioselectivities were satisfactory (81-90% ee) in the case of imines derived from a,(3-unsaturated aldehydes and moderate (52-77% ee) for aromatic substrates. 

A BINOL-derived phosphoric acid derivative has been used as a catalyst in the enantioselective synthesis of a-amino phosphonates via hydrophosphonylation of imines with diisopropyl phosphite.82... 

Lefebvre and Evans found that lithium diethyl phosphite [(EtO)2POLi] adds to (Ss)-N-benzylidene-p-toIuenesulfinamide (126) to give (Ss,S)-128 in 85% yield and 84% de.77 The diastereomeric excess was improved to 93% de by using the sodium salt and to >97% with lithium diisopropyl phosphite. Transition state 127, involving si-face attack of the nucleophile, was proposed to account for the favored formation of 128. a-Aminobenzyl phosphonic acid 129 was obtained on hydrolysis of 128.78 Similar results were reported for the addition of diamido phosphite to 126.78... 

Sodium diisopropyl phosphite (1) reacts with dibromodifluoromethane to give tetraisopropyl dinuoromethylene bisphosphonate (2). ... 

A solution of dibromodifluoromethane (5.05 g. 24 mmol) in anhyd hexane (10 mL) was added dropwise over 30 min to a solution of sodium diisopropyl phosphite (1 9.03 g, 48 mmol) in anhyd hexane under N2 at — 78 C. The solution was stirred at this temperature for 3 h then filtered through a bed of Celite 545. Evaporation of the solvent under vacuum left a colorless oil, which was distilled to yield a fraction distilling above 75 C at 0.8 mbar. Purification of this fraction by flash chromatography (silica gel. acetone/ petroleum ether 1 15) yielded the bisphosphonate 2 yield 3.6 g (40%). 

Tetraisopropyl difluoromethylenediphosphonate has been prepared in 40% yield by the reaction of dibromodifluoromethane with sodium diisopropyl phosphite in hexane at -78°C. The reaction is believed to proceed via metal-halogen exchange to give a stabilized carbanion, which reattacks the diisopropyl bromophosphate formed during the transmetallation step. ... 

Regioselective addition of diisopropyl phosphite to protected derivatives of L-vinylglycine, racemic or enantiomerically pure, in xylene at 120°C catalyzed by tert-butyl per-2-ethylhcxanoatc affords the protected aminocarboxyalkylphosphonate in only moderate yield (3S%, Scheme 8.8S). The L-2-amino-4-phosphonobutanoic acid (APB) is isolated as hydrochlorides by acidic hydrolysis with 6 M HCl. 

A solution of diisopropyl phosphite (3.32 g) in dry hexane (20 ml) is treated with sodium (5 mg). When the metal has dissolved, a solution of p-chlorophenyl isocyanate (3.3 g) in hexane (10 ml) is added rapidly at about 30° with stirring and exclusion of moisture. The temperature then rises to about 40°. After 10 min the mixture is heated under reflux for 1.5 h, then filtered and concentrated. The product (4.4 g, 69% m.p. 122-127°) crystallizes and after several recrystallizations from hexane has m.p. 128-128.7°. 

The synthesis of a,j5-dihydroxyphosphonic acids is easily accomplished by the addition of lithiated diisopropyl phosphite to 464. Unfortunately, under these conditions there is no asymmetric induction, and a 1 1 mixture of 563 and 564 is produced, but the two are separable by flash chromatography [177]. The highest ratio of diastereomers (1 3) is obtained using diisopropyl trimethyl phosphite. Treatment of either 563 or 564 with trimethyl-silyl-bromide followed by hydrogenolysis of the benzyl protecting group furnishes the corresponding free dihydroxyphosphonic acid. 

To a 500 mL flask, were added 150 mL carbon tetrachloride and 83.0 g diisopropyl phosphite (0.5 mol). To this solution was added 50.5 g iV-methylmorpholine (0.5 mol), no apparent reaction occurred until refluxing. After 3 h the solvent was removed in vaccum (distillate contained chloroform) the residue was stirred with 200 mL light petroleum and... 

Dimethyl phosphite added to a soln. of (/-PrO)4Ti in isopropanol, and the soln. kept at 40° for 18 h - diisopropyl phosphite. Y 91%. cf. Synth. Meth. 37, 214. F.e. inch partial transesterification with /err-butanol or benzyl alcohol s. M. Froneman, T.A. Modro, Tetrahedron Letters 29, 3327-30 (1988). 

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