Diethyl methylphosphonite

Diethyl methylphosphonite in refluxing dialkylamine is the favored method for the formation of 37/-azepines from nitroarenes,75,176,207 although tributylphosphane and tri-piperidinophosphane are recommended for the deoxygenation of nitrobenzene in piperidine.79 Deoxygenation of nitrobenzene in diethylamine furnishes Ar,Ar-diethyl-3/f-azepin-2-amine, and a range of 5-substituted 3//-azepines 97 have been prepared in a similar manner from 4-sub-stituted nitroarenes.79,176 Curiously, the corresponding 2-substituted nitroarenes, with the exception of 2-nitrotoluene, yield only tarry products. 

The reaction of diethyl methylphosphonite (59) with methyl N-chlo-roacetimide has been studied.30 Besides the normal Arbuzov product (60) large amounts of dialkyl methylphosphonates (61) and (62) are formed, presumably as a result of initial halogen attack. Whether (60) is formed directly (N-attack) or via (63) has not yet been clarified. A simple method to prepare N,0,0 -trialkyl phosphoramid-... 

Application of the fragmentation reaction to a mixture of the isomeric 1,2,5-trimethyl-3-phospholcnes (5a) and (Sb) gives (ra/tr,rran.r-hexadiene-2,4 (6) in quantitative yield together with diethyl methylphosphonite (7). Since the diene (6) is the most stable isomer, it is not possible to comment on the stereospecificity of the reaction. 

Much of the work on deoxygenation of aromatic nitro and nitroso compounds by tervalent phosphorus reagents has been reviewed.3 Triethyl phosphite has been used frequently, but diethyl methylphosphonite was found to be superior for the deoxygenation of nitro compounds.3,263 The isolation of azepines from such reactions (Scheme 42) indicated the initial formation of arylnitrenes. However, a marked influence of the nucleophile upon the direction of the apparent migration of the nitrene—away or toward an ortho substituent—was noted (Scheme 42).264 Evidence that the same intermediates are involved in the azepine forming reactions from phenyl azides and nitro-benzenes was obtained by a careful examination of the azepines formed from meta-substituted derivatives (Scheme 43). The ratios of the azepines 216 and... 

NiCl2 also catalyses the phosphonation of halothiophenes by phosphite and phos-phonite esters. Under NiCl2 catalysis, 2-bromoacetanilide and diethyl methylphosphonite afford 98% of ethyl [(2-acetamidophenyl)methyl]phosphinate . 

The key step in another synthesis is a Michaelis-Arbusov reaction of diethyl methylphosphonite with the JV-protected 2-amino-4-bromobutanoic acid. According to apaper from the Monsanto company [15], the latter may be obtained from bromobutyrolactone, which is first treated with phthalimide, and after ring-opening, esterified. [16]... 

Diethyl methylphosphonite 2-Amino-3H-azepines from nitrobenzenes... 

Nitrobenzene, diethyl methylphosphonite, and a large excess of diethylamine refluxed 5 days at 55° under Ng 2-diethylamino-3H-azepine. Y 83%. - Diethyl methylphosphonite had the highest reducing activity of a series of phosphorus(III) reagents. F. e. s. J. I. G. Cadogan and M. J. Todd, Soc. (C) 1969, 2808. 

Diethyl methylphosphonite added dropwise during 2 min. to a mixture of 2 moles of CGI4 and 4 moles of ethanol, whereupon after a further 2 min. a vigorous reaction occurs, the product isolated after 2 hrs. refluxing diethyl methylphosphonate. Y 86%. F. e., also with BrGClg, s. A. J. Burn and J. I. G. Gadogan, Soc. 1963, 5788. 

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