Catalytic Asymmetric Syntheses of Quinolizidines by Dirhodium-Catalyzed Dearomatization of Isoquinolinium/Pyridinium Methylides–The Role of Catalyst and Carbene Source
作者:Xichen Xu、Peter Y. Zavalij、Michael P. Doyle
DOI:10.1021/ja406482q
日期:2013.8.21
enantioenriched substituted quinolizidines has been achieved by chiraldirhodium(II) carboxylate-catalyzed dearomatizing formal [3 + 3]-cycloaddition of isoquinolinium/pyridinium methylides and enol diazoacetates. Coordination of Lewis basic methylides to dirhodium(II) prompts the rearrangement of the enol-carbene that is bound to dirhodium to produce a donor-acceptor cyclopropene. The donor-acceptor
Cycloaddition reactions of cycloimmonium ylides with triphenylcyclopropene
作者:Kiyoshi Matsumoto、Takane Uchida
DOI:10.1039/p19810000073
日期:——
course of the reaction is discussed qualitatively. The pyrazinium dicyanomethylide (16) with TPP produces the 7-azaindolizine (19), whereas pyridazinium (17) and phthalazinium (18) dicyanomethylides give the primary adducts (20) and (21), respectively. Reaction of pyridinium bis(alkoxycarbonyl)methylides (22) with TPP gives, however, generally poor or no yield of the indolizines.
at the ylide carbon undergo cycloadditions with aryl-substituted olefins (acenaphthylene, (E)- and (Z)-stilbenes, indene, and styrene), alkyl-substituted olefins (norbornene, (Z)-3-hexene-1,6-dinitrile, 1-hexene, 2-propen-1-ol, and 3-(trimethylsilyloxy)propene), and electron-rich olefins (vinylene carbonate, butyl vinylether, and phenyl vinyl sulfide). These cycloadditions proceed in an exclusively
underwent 1,3-dipolar cycloaddition with pyridinium bis(methoxy-carbonyl)methylides to afford the corresponding indolizines (8-methoxycarbonyl-7-azatricyclo[7.6.0.02-7]pentadeca-1,3,5,8-tetraenes) in good to moderate yields. Some molecular orbital considerations are also described on this reaction compared with the results on the reaction of pyridiniumdicyanomethylides with cyclooctyne.