Carbocations as Lewis Acid Catalysts in Diels-Alder and Michael Addition Reactions
作者:Juho Bah、Johan Franzén
DOI:10.1002/chem.201304160
日期:2014.1.20
the carbocation as a highly powerful Lewis acid catalyst for organic reactions. The stable and easily available triphenylmethyl (trityl) cation was found to be a highly efficient catalyst for the Diels–Alder reaction for a range of substrates. Catalyst loadings as low as 500 ppm, excellent yields, and good endo/exo selectivities were achieved. Furthermore, by changing the electronic properties of the
An examination of VANOL, VAPOL, and VAPOL derivatives as ligands for asymmetric catalytic Diels–Alder reactions
作者:Douglas P Heller、Daniel R Goldberg、Hongqiao Wu、William D Wulff
DOI:10.1139/v06-124
日期:2006.10.1
Several derivatives of the vaultedbiarylligand VAPOL were prepared and evaluated as chiralligands for aluminum Lewis acids in the catalyticasymmetricDiels–Alderreactions of methyl acrylate an...
New Lewis acid catalysts for the Diels-Alder reaction
作者:T. Ross Kelly、Sanat K. Maity、Premji Meghani、Nizal S. Chandrakumar
DOI:10.1016/s0040-4039(00)99464-4
日期:1989.1
Catechol boron bromide (1) and ferrocenium hexafluorophosphate (2) function as Lewisacidcatalysts for the Diels-Alderreaction.
儿茶酚溴化硼(1)和六氟磷酸铯(2)充当Diels-Alder反应的路易斯酸催化剂。
Planar Chiral PHANOLs as Double Hydrogen Bonding Donor Organocatalysts: Synthesis and Catalysis
作者:D. Christopher Braddock、Iain D. MacGilp、Benjamin G. Perry
DOI:10.1002/adsc.200404065
日期:2004.8
4,12-Dihydroxy[2.2]paracyclophanediol (PHANOL; 1), and its para-substituted derivatives 2, 5 and 7, were found to catalyse Diels–Alder cycloadditions of α,β-unsaturated aldehydes or ketones with dienes and/or epoxide ringopening reactions with amines. The mode of catalysis by the PHANOLs is via double hydrogen bonding to the two sp2 lone pairs of a carbonyl group or the two lone pairs of the epoxide
发现4,12-二羟基[2.2]对环庚二醇(PHANOL; 1)及其对位取代的衍生物2、5和7可以催化α,β-不饱和醛或酮与二烯和/或环氧化物的狄尔斯-阿尔德环加成反应与胺的开环反应。PHANOLs的催化方式是通过氢键与羰基的两个sp 2孤对或环氧化物的两个孤对进行双氢键合。该PHANOLs的Diels-Alder反应的催化活性的顺序基本上与基于的吸电子基团的能力(一个或多个)的程度在预期的氢键供体强度相关的对位置。相反,由于对双氢键模式的空间干扰,邻位取代的PHANOL 10、11和14没有活性作为催化剂。为支持所提出的双氢键模式,讨论了各种PHANOL的1 H NMR和IR光谱数据。
Iodine‐Catalyzed Diels‐Alder Reactions
作者:Thiemo Arndt、Philip K. Wagner、Jonas J. Koenig、Martin Breugst
DOI:10.1002/cctc.202100342
日期:2021.6.18
The Diels-Alder cycloaddition is the most popular pericyclic reaction with numerous applications in synthesis and catalysis. We now demonstrate that we can perform this reaction under mild and metal-free conditions relying on molecular iodine as the catalyst. Cycloadditions with cyclohexadiene, cyclopentadiene, or isoprene with various dienophiles can be performed typically within minutes in moderate