A-Methylbenzyl alcohol

Charlton121 has recently reported the asymmetric induction in the reaction of dimethyl fumarate and l,3-dihydrobenzo[c]thiophene 2,2-dioxide (198) containing a chiral a-alkoxy group at the 2-position (equation 128). A diastereomeric excess of 2.8 1 of 199 to 200 is achieved by using 198 derived from optically active a-methylbenzyl alcohol. 

Amino-a-methylbenzyl alcohol, a256 2-Amino-3-methylpentanoic acid, i88 2-Amino-2-methylpropane, b511... 

The metabolism of ethylbenzene in humans occurs along one major pathway which is oxidation at the a-carbon, yielding 1-phenylethanol (also called a-methylbenzyl alcohol) as the primary product. A metabolic scheme is presented in Figure 1. The a-carbon of ethylbenzene is a prochiral centre and hydroxylation thus yields a chiral product. The issue of stereoselectivity has been addressed in animal studies (see Section 4.1.2). 

In the hydrogen transfer between propan-2-ol and acetophenone catalyzed by ruthenium catalyst L 2Ru(methallyl)2 (L 2 = chiral diphosphine ligand), Genet et al. observed racemization of a-methylbenzyl alcohol 63 formed as a final product (Scheme 12.8) [28]. 

The ruthenium-catalyzed racemization of a-methylbenzyl alcohol was combined with an enzyme-catalyzed transesterification with lipase. Dinuclear ruthenium complex 64 effectively catalyzes the racemization of a-methylbenzyl alcohol and the combination of 64, p-chlorophenyl acetate, and enzyme N-435 in the reaction of racemic amethylbenzyl alcohol gave enantiomerically pure (R)-a-methylbenzyl acetate in the excellent yield (Eq. 12.26) [29]. 

C8H9BrO 4-bronno-a-methylbenzyl alcohol 5391-88-8 393.15 33.720 1,2 13655 C8H9I 2-iodo-1,4-dimethylbenzene 1122-42-5 500.15 43.899 2... 

First consider the catalyst cost for the dehydration of a-methylbenzyl alcohol. Given that 1 kg of catalyst is required per 100 kg/hr of fee the amount of catalyst required per 100 kg/h of styrene product is approximately (122/104). Three catalysts are required, thus,... 

PRpropylene, PO=propylene oxide, EB=ethylbenzene, EBHP= ethylbenzene hydroperoxide, and MBA=a-methylbenzyl alcohol, S=styrene... 

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