The α-alkylation of ketones using an earth-abundant and nonprecious NiBr2/L1 system is reported. This nickel-catalyzed reaction could be performed in gram scale and successfully applied in the synthesis of donepezil (Alzheimer’s drug) and functionalization of steroid hormones and fatty acid derivatives. Synthesis of N-heterocycles, methylation of ketones, and one-pot double alkylation to bis-hetero
Herein an operationally simple alkylation of methylene ketones with primary alcohols is reported. Use of an inexpensive and earth abundant Mn/1,10-phenanthroline system enables direct access to a series of functionalised branchedketones including one-pot sequential double alkylation and Alzheimer's drug donepezil. Preliminary mechanistic investigation, determination of the rate and order of reactions
demonstrate a general and broadly applicable catalytic cross coupling of methylene ketones and secondary alcohols with a series of primaryalcohols to disubstituted branched ketones. A simple and nonprecious Fe2(CO)9 catalyst enables one-pot oxidations of both primary and secondary alcohols to a range of branched gem-bis(alkyl) ketones. A number of bond activations and formations selectively occurred in
Under borrowinghydrogen conditions, NHC–iridium(I) catalyzed the direct or one-pot sequential synthesis of α,α-disubstituted ketones via the alkylation of secondary alcohols with primary alcohols is reported. Notably, the present approach provides a new method for the facile synthesis of α,α-disubstituted ketones and featured with several characteristics, including a broad substrate scope, using easy-to-handle
β-Phenyl Quenching of Triplet Excited Ketones: How Critical Is the Geometry for Deactivation?
作者:Subhas Samanta、Brijesh Kumar Mishra、Tamara C. S. Pace、Narayanasami Sathyamurthy、Cornelia Bohne、Jarugu Narasimha Moorthy
DOI:10.1021/jo060200e
日期:2006.6.1
The phenomenon of β-phenyl quenching has been examined by laser-flash photolysis in a series of α- and/or β-substituted ketones 4−8 with similar excited-state characteristics. It is found that α-substitution markedly increases the triplet lifetimes in contrast to β-substitution. The force field calculations for the various staggered conformers of ketones 4−6 and 8-syn show that the lowest-energy conformation