Enantioselective Direct Aldol-Tishchenko Reaction: Access to Chiral Stereopentads
摘要:
The aldol-Tishchenko reaction of aromatic aldehydes in the presence of titanium(IV) tertbutoxide and amino alcohols is described. When used with cinchona alkaloids, stereopentads were isolated for the first time with a high degree of diastereo- and enantioselectivity.
Direct organocatalytic aldol reactions in buffered aqueous media
作者:Armando Córdova、Wolfgang Notz、Carlos F. Barbas III
DOI:10.1039/b207664k
日期:——
Organocatalytic cross-aldol reactions catalyzed by cyclic secondary amines in aqueous media provide a direct route to a variety of aldols including carbohydrate derivatives and may warrant consideration as a prebiotic route to sugars.
Direct Asymmetric Aldol Reaction Catalyzed by C2-Symmetrical Chiral Primary Amine Organocatalysts
作者:Gong-Jian Zhu、Chao-Shan Da、Ya-Ning Jia、Xiao Ma、Lei Yi
DOI:10.2174/157017810790533904
日期:2010.1.1
C-2-symmetrical chiral primaryamines were synthesized from chiral BINOL and diamines. Then their catalytic activities in the asymmetricaldolreactions were evaluated, and the result indicated that 1c was the optimal organocatalyst. The reaction of a variety of aromatic aldehydes with aliphatic ketones, catalyzed by 20 mol % 1c in the addition of benzoic acid in carbon tetrachloride, afforded the aldol products
A NOVEL NUCLEOPHILIC SUBSTITUTION OF THE FORMYL GROUP IN p-NITROBENZALDEHYDE WITH SOME CARBANIONS
作者:Genji Iwasaki、Seitaro Saeki、Masatomo Hamana
DOI:10.1246/cl.1986.173
日期:1986.2.5
p-Nitrobenzaldehyde reacts with some active methylene compounds in the presence of a strong base at low temperatures to give p-substituted nitrobenzenes by the two-step course involving the initial formation of the aldol adducts and the subsequent displacement of the carbinol moieties with excess carbanions.
regio- and diastereoselectivity and enantioselectivity under ambient temperature. Significantly, the reactions accommodate the synthetically important but challenging substrates, such as linear aliphaticketones, with high regioselectivity and unprecedented syn diastereoselectivity. These results are in sharp contrast with the secondary amine mediated similar reactions wherein anti diastereoselectivity
Organocatalytic Asymmetric<i>syn</i>-Aldol Reactions of Aldehydes with Long-Chain Aliphatic Ketones on Water and with Dihydroxyacetone in Organic Solvents
作者:Ming-Kui Zhu、Xiao-Ying Xu、Liu-Zhu Gong
DOI:10.1002/adsc.200800105
日期:2008.6.9
syn-aldol reaction of aliphatic ketones with aromatic aldehydes catalyzed by a primary amino acid-based organocatalyst afforded the syn-aldol adducts in high yields with excellent diastereo- and enantioselectivities (up to > 20/1 dr, >99% ee), and a highly enantioselective syn-aldol reaction of dihydroxyacetone with a variety of aldehydes in THF proceeded with 14/1 to >20/1 dr and 92 to >99% ee. Water not