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).
Metal‐Free Hydrosilylation of Ketenes with Silicon Electrophiles: Access to Fully Substituted Aldehyde‐Derived Silyl Enol Ethers
作者:Avijit Roy、Martin Oestreich
DOI:10.1002/chem.202100877
日期:2021.6.4
catalysts is reported. The boron Lewis acid tris(pentafluorophenyl)borane accelerates the slow uncatalyzed reaction of ketenes and hydrosilanes, thereby providing a convenient access to the new class of β,β-di- and β-monoaryl-substituted aldehyde-derived silyl enolethers. Yields are moderate to high, and Z configuration is preferred. The corresponding silyl bis-enol ethers are also available when using
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。
Access to Quaternary Stereogenic Centers via Rhodium(III)-Catalyzed Annulations between 2-Phenylindoles and Ketenes
作者:Xifa Yang、Yunyun Li、Lingheng Kong、Xingwei Li
DOI:10.1021/acs.orglett.8b00497
日期:2018.4.6
Rh(III)-catalyzed C–H activation of arenes and mild oxidative [4 + 2] annulative coupling with ketenes have been realized. The uniquely high reactivity of the C(3) of 2-phenylindoles was successfully utilized to facilitate the reductive elimination process, leading to efficient synthesis of cyclic products with a quaternary carbon stereocenter.
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.