Triphenyl phosphite, conversion into

Primary alcohols can be reduced to hydrocarbons in two steps conversion into the iodide with triphenyl phosphite methiodide (methyltriphenoxyphosphonium iodide, 1, 1249 2. 446 ), followed by reduction with sodium cyanoborohydride in HMPT. 

At about 98% conversion, hexamethylene diamine is obtained in 90% yield. The process is a liquid-phase operation, carried out at 120°C. The catalyst is a triphenyl phosphite-Ni(0) complex. It appears that the addition of a promoter such as zinc chloride to the nickel ligand results in a composition that catalyzes the conversion of 2-methylbutenenitrile (the undesired branched isomer) into the linear 3-pentenenitrile [173], which may be recycled into the second process step for isomerization to 4-pentenenitrile. 

When epoxy ester 35 was subjected to these reaction conditions, acetal 36 was formed as a single diastereomer [55]. Hydrolysis of the acetal afforded an enone, thus the net transformation represented a new conversion of an ester into an a,jS-unsaturated ketone. Wipf and Methot used this reaction in a synthesis of pyridazinones [56] (Scheme 9). The optimized conditions included addition of 5 mol% of triphenyl phosphite to the reaction mixture and adsorbing AgCl04 onto Celite to improve the stability and simplify the handling of the reagent. Conjugate addition to 36 followed by hydrolysis formed enone 37. A second cuprate addition, followed by cyclization using hydrazine and subsequent oxidation afforded pyridazinone 38 in 86% yield from 36. 

Attempts to convert the sulfones back into PASHs have been successful with a number of agents such as various metals (zinc, tin, magnesium, aluminum, iron, and nickel) in acetic acid, palladium on carbon with hydrazine, stannous chloride, lithium triethylborohydride, diphenylsi-lane, sodium borohydride, boron trifluoride, dicyclohexylcarbodiimide, triethyl phosphite, dimethyl dichlorosUane with lithium aluminum hydride, diphenylsilane, and triphenyl phosphine with iodine. However, none of them cleanly effect this conversion. 

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