Trimethyl phosphite, reaction with cyclic

Trimethyl phosphite reacts with methyl pyruvate to give a liquid mixture of the two possible diastereoisomeric cyclic orthophosphates on treatment with one equivalent of 2A1 sodium hydroxide these yield the diastereoisomeric dimethyl C,C-dimethyltartrates. The reaction represents a novel method for the formation of a C —C bond. 

Basic hydrolysis of the products from the reaction of 3-P-D-ribofuranosyl-adenine with phosphorus oxychloride in trimethyl phosphite gave the cyclic phosphoramidate (620) as well as the expected 5 -phosphate. Phosphoramid-ates e.g. (621)] have been obtained from the reaction between nucleoside 5 -azides and 3 -silylphosphites the silylation reaction and azide condensation were conducted simultaneously (Scheme 95). ... 

Vicinal syn- and aufi-diols, as shown in Figure 4.42, can be prepared diastereoselectively (cf. Figures 8.10,8.13-8.15,8.32). In the Corey-Winter process they are first converted into cyclic thiocarbonates (cf. Section 6.4.4 for a similar reaction mechanism). Upon heating in trimethyl phosphite, these thiocarbonates furnish olefins. In what is evidently a one-step reaction, phosphorus and sulfur combine with one another and the five-membered heterocycle fragments. C02 is released and the olefin results from a xyu-elimination. Because of the latter, a syu-diol gives the trans-oieim and an anti- diol gives the cw-olefin in the Corey-Winter sequence. 

The di-O-tosylates (prepared by action of tosyl chloride in pyridine) are reduced with zinc (Nal/Zn route e Tipson-Cohen reaction) [13]. Cyclic ortho-esters (prepared by reaction of the diol with ethyl orthoformate) are transformed into olefins by simple heating in the presence of acids (Eastwood reaction, route b) [14]. Cyclic thiocarbonates (obtained by reaction of a diol with thiophosgene or (V,(V -thiocarbonyl-di-imidazole) are reduced to olefin with trimethyl phosphite (Corey-Winter method, route c) [15]. Finally, reduction of vicinal di-xanthates with tri- -butyltin hydride according to the Barton procedure [16] affords olefins via a reductive elimination process route a). The Corey-Winter, Garegg, and Tipson-Cohen methods are most commonly applied for deoxygenation of sugar diols. 

Cyclic thionocarbonates (78) by heating with trimethyl phosphite yield (Z)-alkenes (84) (the Corey-Winter reaction). The starting thionocarbonates (78) may be prepared by condensation of thiophosgene with v/c-glycols (82) (X = 0) or v/c-thiols (82) (X = S) (Scheme 43). The Corey-Winter reaction may proceed via the carbenoid intermediate (83), which subsequently collapses to yield the (Z)-alkene... 

Olefin synthesis. Corey and Winter" devised a novel olefin synthesis from 1,2-diols utilizing in the first step the reaction with thiocarbonyldiimidazole (2), a reagent prepared from 2 moles of imidazole and 1 mole of thiophosgene. Corey postulated that treatment of the cyclic thionocarbonate (3) with a reagent which would abstract sulfur to form the curbenc (4) would effect cis elimination to the olefin and found that trimethyl phosphite effects this reaction cleanly and in high yield. [Pg.1350]

It is evident that the interaction of a phosphorus(III) triester and the alkylating species RX can be pictured as an S 2 process (reaction 2) or, for those alkylating reagents capable of forming a carbocation, as an S l process (reaction 3). Several reactions testify to the importance of carbocationic carbon for the Michaelis-Arbuzov reaction in pursuance of its normal course they include the ease of reaction of cyclopropene dihalides, already encountered, and the ready formation of complexes with species having particularly weakly nucleophilic counter ions. Phosphonic acid formation also takes place with cyclic azonium salts and related ions. 9-Chloroacridine reacts with triethyl phosphite to afford a product thought to be the bisphosphonic acid ester 49 The related phosphonic esters 51 are obtainable when the onium salts 50 (X = NH, NR, O or S) are treated with trimethyl... 

Reaction of the initially formed acylphosphonate with a second mole of trimethyl phosphite leads to the formation of a cyclic product with one pentacoordinated phosphorus atom. Further reaction of this oxaphospholene with a second molecule of butenoyl chloride, followed by the loss of methyl chloride, leads to the final product. ... 

The synthesis of the target compounds started from tetra-O-benzyl derivative 101 (90HCA1338) (Scheme 25). Ozonolysis followed by the Abramov reaction with trimethyl phosphite in acetic acid gave a 3 2 ratio of the epimeric phosphonates 102 and 103. Conversion of 102 to the corresponding cyclic phosphonate with aqueous sodium hydroxide gave a mixture of the methyl esters 104 and 105 (1 2). From each isomer, reduction... 

Reaction with Di- and Polyols. Although intermolecular dehydration between two molecules of alcohols to afford acyclic ethers usually does not occur with the DEAD-TPP system, intramolecular cyclization of diols to produce three to seven-membered ethers is a common and high yielding reaction. Contrary to an early report, 1,3-propanediol does not form oxetane. Oxetanes can be formed, however, using the trimethyl phosphite modification of the Mitsunobu reaction. The reaction of (5)-1,2-propanediol and ( )-l,4-pentanediol with DEAD and TPP affords the corresponding cyclic ethers with 80-87% retention of stereochemistry at the chiral carbon, while (5)-phenyl-1,2-ethanediol affords racemic styrene oxide. In contrast to the reaction of the same 1,2-diols with benzoic acid (eq 4), oxyphos-phonium salts (25a) and (25b) have been postulated as key intermediates in the present reaction (eq 20). ... 

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