Reduction of allyl alcohol

To gain mechanistic insight into the reduction of allylic alcohol 46, the reaction was monitored by measuring the hydrogen evolution and ReactIR3). The addition of 0.5 equiv of Red-Al resulted in the evolution of 2 mol of H2 and the formation of the dimeric intermediate 83 (Scheme 7.26) [19b, 30], Figure 7.2 shows the cumulative evolution of hydrogen (mmol) and the cumulative amount of Red-Al ... 

Y. Nakamura, M. Okada, H. Horikawa, T. Taguchi, Preparation of c5-fluorinated homo-allylic alcohol derivatives via regioselective hydride reduction of allylic alcohol derivatives, J. Fluor. Chem. 117 (2002) 143-148. 

Reduction of unsaturated halides 0-78 Reduction of allylic alcohols 0-82 Reductive cleavage of enamines 0-86 Coupling of vinylic halides 0-87 Coupling of unsaturated halides with organometallic reagents 0-88 Coupling of allylic halides, tosylates, or acetates... 

The double bond shift is explained in terms of a kinetically controlled protonation of the anion formed in an ECE process the anion would have the highest negative charge a to the ester group. Such a double bond shift seems to be rather general also for the indirect reduction of allyl alcohols.388... 

Reduction of derivatives of ally lie alcohols. Nickel boride can effect reduction of allylic alcohols to alkenes, but yields are generally improved by reduction of the acetates, benzoates, or trifluoroacetates.1 Reduction of allylic benzyl ethers to alkenes is effected in higher yield with Raney nickel. Methyl ethers are not reduced by either reagent. The trimethylsilyl ethers of allylic alcohols are reduced to alkenes by nickel boride in diglyme.2... 

For reduction of allylic alcohols with double bond transposition, see page 229, Section 4. 

The V(OH)2/Mg(OH)2 gel is believed to be a solid solution with a lattice similar to Cdl2, and the yield of hydrazine reaches a maximum with the magnesium to vanadium ratio in the range 1 5-10 (133). Shilov finds (1) no 14N isotope effect corresponding to the Schrauzer mechanism, (2) that there is no evidence for vanadium IV), (3) that the reduction of allyl alcohol is independent of, and competitive with, dinitrogen reduction, and (4) a different dependence on P 2 from the square dependence claimed. In short, no evidence for diazene, but much more for a direct reduction to hydrazine (136). 

Olefinic alcohols react smoothly with hydrogen over platinum oxide catalyst at room temperature. The procedure is illustrated by the preparation of dihydrocholesterol from cholesterol. Cinnamyl alcohol. CjH5CH = CHCH20H, is reduced to dihydrocinnamyl alcohol by lithium aluminum hydride. The reduction of allyl alcohol to n-propyl alcohol by the reagent, however, is unsatisfactory, ... 

Reductions of allylic alcohols can also go stereospecifically (Scheme 62). However, they are not always substrates. For example, the allylic alcohol arising from reduction of the formyl group of the a, -unsaturated aldehyde (122) is not reduced to (123) by B. sulfurescens. ... 

As this reaction proceeds, [rr-allyl PdClJg is gradually formed. Since the 77-allyl group represents a reduction of allyl alcohol, it has been suggested that allyl alcohol reacts with PdCl2 to give the 77-allyl complex and CeHioOa (750) ... 

Fig. 17. The competition between hydrogenation and isomerization in the Ru-BINAP-cata-lyzed reduction of allylic alcohols...

Reduction of allylic alcohols (1, 592, ref. 32). The preparation of 1,1-diphenyl-cyclopropane has now been published.1... 

During the catalytic reduction of allyl alcohol,(2) the saturation of the double bond (and propanol formation) may also be accompanied by isomerization (with formation of propionaldehyde) and C-0 or C-C bond cleavage (destruction) via hydrogenolysis, yielding gaseous products (propylene, propane, ethylene, acetylene). 

The mechanism of the reduction of allylic alcohols (Scheme 28) has been studied in detail. The aldehyde is rapidly reduced to the allylic alcohol and its level stays low and constant during reaction. The aldehyde present at equilibrium conditions is then transformed into the saturated aldehyde and then into the final product. The reduction reaction described in Scheme 28 has been scaled to hundreds of grams for the preparation of C5 chiral synthons [149]. 

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