Triisopropyl phosphite

Intramolecular 1,4-addition is useful for macrolide synthesis. An unusual molecule of punctaporonin B (272) has been synthesized by this 1,4-addition of 271(160]. Cyclization to form the seventeen-membered ring macrolide 273 was carried out at 0.1-0.5 vi concentration[161. The choice of ligands seems to be important in the macrocyclization. The 26-membered ring model 274 for a synthesis of the ring system of tetrin A was obtained in 92% yield by using triisopropyl phosphite as a ligand[162]. 

Phosphite esters are formed readily by the reaction of phosphoms haUdes and isopropyl alcohol. Eor example, triisopropyl phosphite [116-17-6] is prepared from phosphoms trichloride [7719-12-2] and isopropyl alcohol at low temperatures ia the presence of an acid scavenger, eg, pyridine [110-86-1]. 

Reaction of the cyclopropyl-substituted pivalate (25) with dimethyl benzylidenema-lonate in the presence of a palladium catalyst gave a mixture of alkylidenecyclo-propane (26) and vinylcyclopropane (27). The ratio of these two adducts is found to be quite sensitive to the choice of ligand and solvent. While triisopropyl phosphite favors the formation of the methylenecyclopropane (26), this selectivity is completely reversed with the use of the bidentate phosphite ligand dptp (12). Interestingly there was no evidence for any products that would have derived from the ring opening of the cyclopropyl-TMM intermediate (Scheme 2.8) [18]. 

Perhydroindans (46) and (47) could be obtained in 73% yield from the carbonate (48) with only minor amounts of elimination product. The use of BSA and the triisopropyl phosphite-palladium acetate catalytic system provides further improvement. The low cisitrans selectivity in the formation of the first ring, and rapid subsequent cyclization account for the fact that the ratio of (46) to (47) is only 2 1 (Scheme 2.14). Even the presence of a bulky trialkylsiloxyl substituent adjacent to the vinyl sulfone moiety has only a minor influence on the cisitrans selectivity [24]. 

ETHYL BENZOATE VIA THE NITRO-SOAMIDE DECOMPOSITION, 47, 44 Decachlorobi-2,4-cyclopentadienyl, dechlorination by triisopropyl phosphite, 46, 93 a-Decalones, 46, 82 Decanoyl fluoride, 46, 6 Decarboxylation, in formation of couma-rone from o-formylphenoxyacetic acid, 46, 28... 

In another reaction tetraalkylmethylenediphosphonates, obtained by Arbusov reaction from triisopropyl phosphite and dibromomethane [see Eq. (58)], were... 

C9H21BO3 5419-55-6) see Losartan potassium Rofecoxib triisopropyl phosphite... 

Kinetic studies of the oxidation of phosphites such as triisopropyl phosphite with BTSP 1949 to give phosphates such as triisopropyl phosphate [177] led to the discovery that oxidation of diphosphite nucleotide intermediates such as 2008 with BTSP 1949 at -20 °C in the presence of TMSOTf 20 (instead of iodine in... 

Diisopropyl methylphosphonate is an organophosphate compound that was first produced in the United States as a by-product of the manufacture of the nerve gas isopropyl methylphosphonofluoridate (GB, or Sarin) (ATSDR 1996 EPA 1989 Robson 1977, 1981). It is not a nerve gas and is not a metabolite or degradation product (Roberts et al. 1995). Diisopropyl methylphosphonate constitutes approximately 2-3% of the crude GB product, but it is neither a metabolite nor a degradation product of GB (EPA 1989 Rosenblatt et al. 1975b). Diisopropyl methylphosphonate is not normally produced except for its use in research. One method of producing diisopropyl methylphosphonate is to combine triisopropyl phosphite and methyl iodide. The mixture is then boiled, refluxed, and distilled, yielding diisopropyl methylphosphonate and isopropyl iodide (Ford-Moore and Perry 1951). Diisopropyl methylphosphonate may also be prepared from sodium isopropyl methylphosphonate by a reaction at 270° C, but a portion of the resulting diisopropyl methylphosphonate is converted to trimethylphosphine oxide at this temperature (EPA 1989). 

The presence of trialkyl phosphite 198 in the above mentioned reduction of the gem-dibromocyclopropanes 150 with dialkyl phosphonate and triethylamine alters the reaction course. Dialkyl cyclopropanephosphonates 199 are produced via reductive phosphonation [104]. Trialkyl phosphite participates in the carbon-phosphorous bond formation. It is supported by the exclusive formation of diisopropyl cyclopropylphosphonate in the phosphonation reaction with diethyl phosphonate and triisopropyl phosphite. (Scheme 74)... 

Preparation of 5-(3-benzoylpropionyl)-3-deoxy-3-diisopropoxyphosphinylmethyl-l,2-di-0-acetyl-D-ribofuranose — Reaction of an alkyl bromide in a carbohydrate series with triisopropyl phosphite... 

A solution of 5-0-(3-benzoylpropionyl)-3-deoxy-3-bromomethyl-l,2-di-O-acetyl-D-ribofuranose (2.35 g, 4.89 mmol) in triisopropyl phosphite (17 g, 81 mmol) was heated at 160 to 180°C with exclusion of moisture for 72 h. Volatile materials were removed under reduced pressure, and the residue was purified by chromatography on a silica gel column (48 x 2.7 cm) eluting with chloroform ethyl acetate (1 1). From the 150 to 500 ml eluent, there was isolated the pure 5-(3-benzoylpropionyl)-3-deoxy-3-diisopropoxyphosphinylmethyl-l,2-di-O-acetyl-D-ribofuranose (1.73 g, 68%) as an oil that exhibited IR and NMR spectra and analyses in accord with the proposed structure. 

Corresponding replacement of halide from an unconjugated vinylic site has also been reported. The use of the sodium salts of dialkyl phosphites in tetrahydrofuran at low temperature has been found to provide the vinylic phosphonate in good yield,72 (Figure 6.22) and triisopropyl phosphite serves similarly to replace a fluoride of trifluoroiodoethene (Figure 6.23).91 The reaction proceeds ste-reospecifically to replace the fluoride cis to the iodide, and in continuing reaction the iodide is replaced. 

E)-2-Chlorovinyl phenyl ketone (1.83 g, 11 mmol) and triisopropyl phosphite (2.08 g, 10 mmol) were heated under an argon atmosphere for 1 h at 120 to 130°C. When all of the isopropyl chloride formed had distilled, the residue was chromatographed on a column of silica gel (18 g) being eluted with a 1 1 mixture of methylene chloride-ethyl acetate. The eluent was evaporated of solvent and the residue vacuum distilled to give pure diisopropyl (E)-2-benzoylvinylphosphonate (1.33 g, 45%). 

Pheny 1-3-pheny 1 imino-3-// -indole N -oxide (an indolic nitrone) reacts with triethyl and triisopropyl phosphite in refluxing xylene and fert-butylbenzene to give 2-phenylimino-3// -indole (indolenine) in very good yield (505). 

The [3+2] cycloaddition of trimethylenemethane (TMM) on the unsaturated lactam 288 worked efficiently with the use ofPd[P(0 Pr)3]4 (generated in situ from palladium(n) acetate (20mol%) and triisopropyl phosphite (160mol%)). The reaction proceeded cleanly in refluxing toluene to afford exclusively the desired cycloadduct 290 in 80% isolated yield (Equation 48) <2003TL5033>. 

Reductive cleavage of enedicarbonates.1 2 The dicarbonates of enediols in the presence of this Pd(0) complex and triisopropyl phosphite undergo reductive elimination to afford 1,3-dienes. 

Another hydride for the preparation of aldehydes from acyl chlorides is obtained by treatment of a mixture of cuprous chloride and triphenylphos-phine, trimethyl phosphite or triisopropyl phosphite in chloroform with an ethanolic solution of sodium borohydride. Such reagents reduce acyl chlorides to aldehydes in acetone solutions at room temperature in 15-90 minutes in yields ranging from 57% to 83% [115],... 

N,N-Diethyl-l,2,2-trichlorovinylamine has been prepared by the action of trimethyl, triethyl, or triisopropyl phosphite or triphenylphosphine on N,N-diethyl-2,2,2-trichloroacetamide., These methods require a reaction temperature of 150-160° and several distillations in order to obtain a pure product. Consequently, the yields of the vinylamine are lower than by the present procedure.3... 

Triisoamyl phosphate, triisobutyl phosphate, triisooctyl thiophosphate and triisopropyl phosphite see entries in Chapter 4. 

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