Highly efficient organocatalysts for the asymmetric aldol reaction
作者:C. G. Jacoby、P. H. V. Vontobel、M. F. Bach、P. H. Schneider
DOI:10.1039/c7nj04424k
日期:——
synthetic route. The highly efficient five step methodology did not require intermediary purification and provided the compounds in high yields. The catalysts were successfully applied in the asymmetric direct aldolreaction between aromatic aldehydes and cyclic ketones in aqueous media. Aldol adducts were obtained in high yields with perfect stereoselectivities (up to >99% e.e. and >19 : 1 d.r.).
Unprecedented bifunctional enamine–metal Lewisacidcatalysts have been developed. In this bifunctional catalytic system, a tridentateligand tethered with a chiral secondary amine was designed to solve the acid–base self-quenching problem leading to catalyst inactivation. This new bifunctional enamine–metal Lewisacidcatalyst was found to catalyze aldol reactions of ketones efficiently in high yields
<i>N</i>-Primary-Amine-Terminal β-Turn Tetrapeptides as Organocatalysts for Highly Enantioselective Aldol Reaction
作者:Feng-Chun Wu、Chao-Shan Da、Zhi-Xue Du、Qi-Peng Guo、Wei-Ping Li、Lei Yi、Ya-Ning Jia、Xiao Ma
DOI:10.1021/jo9005766
日期:2009.7.3
solution. They were first applied to catalyze aldolreactions, and were found to be effective catalysts for the transformations. The tetrapeptide Val-d-Pro-Gly-Leu-OH (1g) was the optimal organocatalyst. It was shown that the intensive β-turn conformation, indicated by CD and NOESY spectra, contributed to the (R)-aldol and high enantioselectivity of the reaction of acetone in MeOH, whereas the sharply varied
设计并合成了四肽,该四肽包含一个终止的伯胺和构象受限的d -Pro-Gly或d -Pro-Aib(2-氨基异丁酸)链段作为强β-转核元素,并通过N-模块二肽与溶液中的C模块二肽。它们首先被用于催化羟醛反应,并被发现是有效的转化催化剂。四肽Val- d -Pro-Gly-Leu-OH(1g)是最佳的有机催化剂。结果表明,在密集的β转角构象,通过CD和NOESY光谱表明,促成了(ř)-丙酮中的丙酮反应具有较高的对映选择性,而急剧变化的构象应有助于1,2-二氯乙烷(DCE)中反应的低对映选择性和(S)产物。羟基丙酮反应中的不对称诱导不受溶剂的影响,在MeCN中添加1克添加剂(S)-BINOL可达到主要的反产物。
Pyrimidine-Derived Prolinamides as Recoverable Bifunctional Organocatalysts for Enantioselective Inter- and Intramolecular Aldol Reactions under Solvent-Free Conditions
作者:Pascuala Vizcaíno-Milla、José M. Sansano、Carmen Nájera、Béla Fiser、Enrique Gómez-Bengoa
DOI:10.1002/ejoc.201500007
日期:2015.4
ChiralL-prolinamides 2 containing the (R,R)- and (S,S)-trans-cyclohexane-1,2-diamine scaffold and a 2-pyrimidinyl unit are synthesized and used as general organocatalysts for intermolecular and intramolecular aldolreactions with 1,6-hexanedioic acid as a co-catalyst under solvent-free conditions. The intermolecular reaction between ketone–aldehyde and aldehyde–aldehyde must be performed under wet
Highly Diastereo- and Enantioselective Aldol Reactions in Common Organic Solvents Using<i>N</i>-Arylprolinamides as Organocatalysts with Enhanced Acidity
作者:Jarugu Narasimha Moorthy、Satyajit Saha
DOI:10.1002/ejoc.200800960
日期:2008.12.29
steric crowding has been synthesized and its catalytic activity explored for enantioselectivealdolreactions. In DMF containing 10 mol-% of TFA, all arylamides are found to catalyze the reaction between cyclohexanone and a variety of electrophilic aldehydes leading to aldols in excess of 90 % yield and >95 % enantioselectivity. The perfluorophenyl catalyst 8 is found to perform best with a broad substrate