Rhodium-Catalyzed Regio-, Diastereo-, and Enantioselective Intermolecular [4+2] Carbocyclization of 4-Alkynals with Electron-Deficient Alkenes
作者:Ken Tanaka、Yuji Hagiwara、Masao Hirano
DOI:10.1002/ejoc.200600383
日期:2006.8
We established that a cationic rhodium(I)/dppf or dppb complexcatalyzes a regio- and diastereoselective intermolecular [4+2] carbocyclization of 5-trimethylsilyl-4-pentynals with electron-deficient alkenes leading to cyclohexanones. We also established that a cationic rhodium(I)/(R,R)-Walphos complexcatalyzes a regio- and enantioselective intermolecular [4+2] carbocyclization of 5-substituted 4-pentynals
We have developed catalytic isomerizations of 5-alkynals to γ-alkynyl ketones and cyclopent-1-enylketones using [RhP(OPh)3}2]BF4 as a catalyst. Cu(OTf)2 and AgBF4 are also effective catalysts for the formation of γ-alkynyl ketones. The substituents at the 4-positions in 5-alkynals play important roles in the selection of two different isomerization pathways. The first catalytic endo/trans hydroacylation
Rh-Catalyzed [4+2] Annulation of 4-Alkynals with Isocyanates and Its Application to the Parallel Kinetic Resolution of Unfunctionalized 4-Alkynals
作者:Ken Tanaka、Yuji Hagiwara、Masao Hirano
DOI:10.1002/anie.200504470
日期:2006.4.21
Synthesis of substituted 6-imino-2-piperidinones by Rh-catalyzed [4+2] annulation of 4-alkynals with carbodiimides
作者:Ken Tanaka、Marina Mimura、Daiki Hojo
DOI:10.1016/j.tet.2009.06.115
日期:2009.10
Synthesis of substituted 6-imino-2-piperidinones has been achieved by cationic rhodium(1)/dppp complex-catalyzed [4+2] annulations of various 4-alkynals with carbodiimides at room temperature. The reactions of benzene-linked 4-alkynals (2-alkynylbenzaldehydes) and carbodiimides also proceeded at room temperature, affording the corresponding 6-imino-2-piperidinones. (C) 2009 Elsevier Ltd. All rights reserved.
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