Halides alcohols, prim

Alcohols from oxo compds. 20 eqs. NaBH4 added to a soln. of 5 eqs. ZrC in THF at room temp, under N2, a soln. of 4 eqs. acetophenone in the same solvent added, and the mixture stirred at room temp, for 5 h - 1-phenylethanol. Y 96%. ZrCl4 is inexpensive, easy to use, and does not affect ar. nitro compds. and bromides. F.e., also reduction of carboxylic acids, esters and halides to prim, alcohols, and amides, oximes, alkoximes, nitriles, and imines to amines, s. S. Itsuno et al.. Synthesis 1988, 995-6. 

Prim ry and secondary alcohol are best converted into olWyl halides by treatment with such reage nts as thicmyL chloride CSOClj> or phosphorus tribromide (PBra). These reactions, which normally take place readily under mild conditions, are loss acidic and less tikoly to cause acid-catalyzed rearrangemetitB than the HX method. 

Prim, alcohols from halides under mild, neutral conditions... 

A soln. of methyl 5-iodopentanoate in dry dimethylformamide treated with 2 eqs. (Bu3Sn)20 in the presence of 1.3 eqs. AgOTs for 5.5 h at 20°, followed by an aq. work-up - methyl 5-hydroxypentanoate. Y 96%. This is the first direct conversion of unactivated prim, iodides and bromides to alcohols under neutral conditions sec. and tert. halides undergo elimination. F.e. and with AgN03 or Ag20 s. M. Gingras, T.H. Chan, Tetrahedron Letters 30, 279-82 (1989). 

A stirred soln. of tri-n-butylhydroxymethylstannane in petroleum ether (b. p. 30-40°) treated under argon at -20° with a soln. of 2 equivalents -butyllithium in hexane, stirred 6 hrs. at room temp., cooled to -78°, treated with 1 equivalent benzaldehyde, and allowed to warm overnight -> product. Y 62%. F. e., also prim, alcohols from halides (cf. Synth. Meth, 20, 614), s. D. Seebach and N. Meyer, Ang. Ch. 88, 484 (1976). 

Hydride reduction to prim alcohol Halide, ester + L1AIH4 (20-2 to 4)... 

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