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.
Catalytic Asymmetric Synthesis of Ketene Heterodimer β-Lactones: Scope and Limitations
作者:Shi Chen、Ahmad A. Ibrahim、Nicholas J. Peraino、Divya Nalla、Mukulesh Mondal、Maxwell Van Raaphorst、Nessan J. Kerrigan
DOI:10.1021/acs.joc.6b01481
日期:2016.9.2
scope exploration, protocol innovations (including double in situ ketene generation for 7 examples), and an application to a cinnabaramide A intermediate are described. The addition of lithium perchlorate (1–2 equiv) as an additive to the alkaloid catalyst system was found to favor formation of the E isomer of the ketene heterodimer. Ten examples were formed with moderate to excellent (E)-olefin isomer
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。
Mechanistic studies of the phosphine-catalyzed homodimerization of ketoketenes
作者:Pei-Hsun Wei、Ahmad A. Ibrahim、Mukulesh Mondal、Divya Nalla、Gero D. Harzmann、Frank A. Tedeschi、Kraig A. Wheeler、Nessan J. Kerrigan
DOI:10.1016/j.tetlet.2010.10.026
日期:2010.12
ketoketenes has been explored and compared with that of the previously reported trialkylphosphite-mediated reactions. NMR studies of the PBu3-catalyzed reaction implicated the involvement of tetravalent phosphonium intermediates. Phosphonium intermediates in the catalytic cycle were trapped through reaction with trimethylsilyl chloride and 4-chlorobenzaldehyde, and the resulting products were characterized
Catalytic Asymmetric Synthesis of Esters from Ketenes
作者:Sheryl L. Wiskur、Gregory C. Fu
DOI:10.1021/ja0506152
日期:2005.5.1
By building on elementary principles of Brønsted acid-base chemistry, a nucleophile-catalyzed method for the asymmetric synthesis of esters fromketenes has been transformed into a much more versatile and effective Brønsted acid-catalyzed process. The product aryl esters can be converted into useful derivatives, such as enantioenriched alcohols and carboxylic acids.