2349-70-4Relevant articles and documents
Experimental and semiemprical studies of chemical reactivity of dialkylcadmium reagents addition to α,β-enones
Ghandi, Mehdi,Shahidzadeh, Mansour
, p. 4918 - 4925 (2006)
Experimental and semiempirical calculations were carried out to study the reactivity of dialkylcadmium reagents addition to α,β-enones. It was demonstrated that α,β-enone such as benzoquinone with low lying LUMO energy reacts via single electron transfer (SET) mechanism with the formation of the 1,2 or 1,4-type alkyl addition product depending on the reaction temperature and substrate structure. Site and chemoselectivity in unsymmetrical benzoquinone derivatives are determined by the stability of the cadmium coordinated semienone complex intermediates and the carbon spin densities of these reactive species respectively. On the other hand, by increasing the LUMO energy of α,β-enone system, the reaction mechanism changes from SET to polar addition affording the 1,4-type alkyl addition product. The establishment of a correlation scale between substrate LUMO energies and reaction mechanism presented in this article will be discussed.
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Florjanczyk,Z. et al.
, p. 21 - 28 (1976)
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Candida antarctica lipase B-catalyzed regioselective deacylation of dihydroxybenzenes acylated at both phenolic hydroxy groups
Miyazawa, Toshifumi,Hamada, Manabu,Morimoto, Ryohei
, p. 44 - 49 (2016/01/16)
Candida antarctica lipase B proved to be highly active in the deacylation of substituted hydroquinones and resorcinols acylated at both phenolic hydroxy groups. The deacylation reactions were much faster than the corresponding direct acylations of these dihydroxybenzenes catalyzed by the same lipase. More importantly, they took place generally in a markedly regioselective manner: the acyloxy group remote from the substituent was preferentially cleaved. The main or exclusive products obtained were the regioisomers of those produced through the direct acylation of the dihydroxybenzenes. In the case of alkyl-substituted hydroquinone derivatives, the regioselectivity increased with an increase in the bulk of the substituent. In the case of 4-substituted diacylated resorcinols, the 3-O-monoacyl derivatives were obtained generally as the sole products. Quite interestingly, some secondary alcohols proved to act as better acyl acceptors than the corresponding primary alcohols in these enzymatic deacylations.
Candida antarctica lipase B-mediated regioselective acylation of dihydroxybenzenes in organic solvents
Miyazawa, Toshifumi,Hamada, Manabu,Morimoto, Ryohei,Maeda, Yuki
, p. 3915 - 3923 (2015/06/02)
Candida antarctica lipase B proved to be a highly active biocatalyst for the direct acylation of phenolic hydroxy groups of substituted hydroquinones and resorcinols, which have rarely been reported so far. More importantly, the acylation reactions took place generally in a markedly regioselective manner: the hydroxy group remote from the substituent was preferentially acylated. In the case of substituted hydroquinones, the selectivity increased with the increase in the bulk of the substituent. Interestingly, the 1-O-monoacylated derivatives were obtained as the sole products in the case of 4-substituted resorcinols.
