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.
Formal [3+2] Cycloaddition of Ketenes and Oxaziridines Catalyzed by Chiral Lewis Bases: Enantioselective Synthesis of Oxazolin-4-ones
作者:Pan-Lin Shao、Xiang-Yu Chen、Song Ye
DOI:10.1002/anie.201003532
日期:2010.11.2
Choose the right cat.: A highly enantioselectivesynthesis of oxazolin‐4‐ones by the formal [3+2] cycloaddition of ketenes and a racemic oxaziridines has been developed (see scheme; cat.=N‐heterocyclic carbenes for disubstituted ketenes or cinchonaalkaloids for monosubstituted ketenes, Ts=4‐toluenesulfonyl).
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
N-Heterocyclic Carbene Catalysis: Enantioselective Formal [2+2] Cycloaddition of Ketenes and N-Sulfinylanilines
作者:Teng-Yue Jian、Lin He、Cen Tang、Song Ye
DOI:10.1002/anie.201102488
日期:2011.9.19
Sultam of swing: Both enantiomers of 1,2‐thiazetidin‐3‐one oxides were obtained in very good yields with excellent enantioselectivities when using N‐heterocyclic carbene catalysts (see scheme; M.S.=molecular sieves, TBS=tert‐butyldimethylsilyl). The products were easily converted into 3‐oxo‐β‐sultams, α‐mercapto amides, and β‐mercapto amines through oxidation or reduction.
摇摆的结果:使用N杂环卡宾催化剂时,1,2-噻嗪丁-3-氧化物的两种对映体均以非常高的收率获得,并具有出色的对映选择性(参见方案; MS =分子筛,TBS =叔丁基二甲基甲硅烷基)。产物可以通过氧化或还原轻松地转化为3-氧代-β-杜马酰胺,α-巯基酰胺和β-巯基胺。
Enantioselective [4+2] cycloaddition of ketenes and 1-azadienes catalyzed by N-heterocyclic carbenes
作者:Teng-Yue Jian、Pan-Lin Shao、Song Ye
DOI:10.1039/c0cc04839a
日期:——
Optically active highly functionalized 3,4-dihydropyridin-2-ones were synthesized by N-heterocyclic carbene-catalyzed [4+2] enantioselective cycloaddition of ketenes and 1-azadienes.