An asymmetric pericyclic cascade approach to 3-alkyl-3-aryloxindoles: generality, applications and mechanistic investigations
作者:Edward Richmond、Kenneth B. Ling、Nicolas Duguet、Lois B. Manton、Nihan Çelebi-Ölçüm、Yu-Hong Lam、Sezen Alsancak、Alexandra M. Z. Slawin、K. N. Houk、Andrew D. Smith
DOI:10.1039/c4ob02526a
日期:——
The reaction of l-serine derived N-arylnitrones with alkylarylketenes generates 3-alkyl-3-aryloxindoles in good yields and excellent enantioselectivities.
NHC-mediated enantioselectiveformal [4+2] cycloadditions of alkylarylketenes with γ-substituted-β,γ-unsaturated α-ketophosphonates is described. A substrate-dependent switch in diastereoselectivity was observed, with γ-aryl α-ketophosphonates providing preferentially the syn-dihydropyranone-phosphonates and γ-methyl α-ketophosphonates favouring the anti-dihydropyranone-phosphonate. In addition, ketene generation
Ketene-diene [4 + 2] cycloaddition products via cation radical initiated Diels-Alder reaction or vinylcyclobutanone rearrangement
作者:Michael Schmittel、Heinke Von Seggern
DOI:10.1021/ja00059a010
日期:1993.3
thermal reaction of the aryl methyl ketenes 1a and 1b with 2 resulted, as anticipated, in the periselective formation of the vinylcyclobutanones 3-6, the aminium ion salt initiated cycloaddition afforded selectively the Diels-Alder products 10 and 11. The potential role of BrOnsted and Lewis acids, the suitability of different one-electron oxidants, and the effect of reactant concentration, reaction time
ketenes from acyl chlorides and amines may be incompatible with TM catalysis (i.e., reactive acyl chloride and amine hydrochloride byproducts). Herein, we detail the unprecedented asymmetric [4+2] cycloaddition of vinyl benzoxazinanones with a variety of ketene intermediates via sequential visible-light photoactivation and palladiumcatalysis. It is well demonstrated that the traceless and transient generation
Chiral spiro phosphoric acid-catalysed enantioselective reaction of ketenes with N–H pyrroles
作者:Qian-Yi Wang、Teng-Fei Liu、Li-Feng Chu、Yun Yao、Chong-Dao Lu
DOI:10.1039/d1cc05307h
日期:——
In the presence of a chiral spiro phosphoric acid catalyst, the asymmetric reaction of disubstituted ketenes with N–H pyrroles occurred to afford enantioenriched C-acylated pyrroles bearing α-stereogenic carbon centres. The described reaction constitutes a rare example of a catalytic asymmetric reaction of ketenes with carbon-based nucleophiles.