Organic Reaction Mechanisms -1998: An Annual Survey Covering the Literature (original) (raw)
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Journal of Fluorine Chemistry, 1999
Reaction of tri¯uoroacetaldehyde ethyl hemiacetal with ene compounds in the presence of a Lewis acid gives-tri¯uoromethylated homoallyl alcohols, the same products as those from the ene reaction of tri¯uoroacetaldehyde, in moderate to good yields. Boron tri¯uoride etherate was found to be most effective in this reaction. This method eliminated many dif®culties encountered on the ene reaction of tri¯uoroacetaldehyde, which is a gas at room temperature and polymerizes to insoluble polymer in the presence of a Lewis acid.
Reaction of enamines with trifluoromethyl containing carbonyl reagents
Journal of Fluorine Chemistry, 2010
The reaction of linear push–pull enamines bearing a methyl group at the α-position with a set of trifluoromethylated carbonyl compounds was investigated. It has been found that the reaction proceeds at the methyl group of the enamines. The first computational study of the reaction between push–pull enamines and strong electrophilic reagents was reported. Out of three pathways considered DFT and MP2 calculations support ene-mechanism previously suggested based on experimental results only.The reaction of linear push–pull enamines bearing a methyl group at the α-position with a set of trifluoromethylated carbonyl compounds was investigated. It has been found that the reaction proceeds at the methyl group of the enamines. The first computational study of the reaction between push–pull enamines and strong electrophilic reagents was reported. Out of three pathways considered DFT and MP2 calculations support ene-mechanism previously suggested based on experimental results only.
Reaction Mechanisms in Organic Synthesis Postgraduate Chemistry Series
2013
A series designed to provide a broad understanding of selected growth areas of chemistry at postgraduate student and research level. Volumes concentrate on material in advance of a normal undergraduate text, although the relevant background to a subject is included. Key discoveries and trends in current research are highlighted, and volumes are extensively referenced and cross-referenced. Detailed and effective indexes are an important feature of the series. In some universities, the series will also serve as a valuable reference for final year honours students.
Journal of Catalysis, 2011
The enantioselective hydrogenation of 2,2,2-trifluoroacetophenone (1) on cinchona-modified Pt, combined with the diastereoselective hydrogenation of cinchonidine and NMR analysis of the modifiersubstrate-product interactions, revealed the key role of the product (S)-1-phenyl-2,2,2-trifluoroethanol (2) in enantioselection. We propose a multiple cycle mechanism including a racemic route (a) on the unmodified sites and three enantioselective routes. In the enantioselective cycles, there is an N-H-O type interaction between the quinuclidine N and the carbonyl O-atom of the substrate. At low conversion, the alkaloid alone is the source of chiral information (route b). With increasing conversion, the weakly acidic minor product (S)-2 forms an adduct with the alkaloid and this complex controls the enantioselection (route c, lower ee). The frequently applied strong acid additive TFA replaces (S)-2 and the alkaloid-TFA complex gives the highest ee (route d). The diastereoselective hydrogenation of cinchonidine disproves a former mechanistic model proposed in the literature.
2004
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