Silylformylation catalyzed by Rh and Rh-Co mixed metal complexes and its application to the synthesis of pyrrolizidine alkaloids
作者:Iwao Ojima、Robert J. Donovan、Masakatsu Eguchi、William R. Shay、Patrizia Ingallina、Anna Korda、Qingping Zeng
DOI:10.1016/s0040-4020(01)87260-4
日期:1993.1
dialkyne, and an alkynyl nitrile proceed in high yields in which alkene and nitrile functionalities are inert for the reaction. Silylformylation is successfully applied to the syntheses of pyrrolizidinealkaloids, (±)-isoretronecanol and (±)-trachelanthamidine, from 5-ethynyl-2-pyrrolidinone (6) in combination with amidocarbonylation.
Cationic complexes of dirhodium(II) with 1,8-naphthyridine: Catalysis of reactions involving silanes
作者:Marino Basato、Andrea Biffis、Gianluca Martinati、Cristina Tubaro、Claudia Graiff、Antonio Tiripicchio、Laura A. Aronica、Anna M. Caporusso
DOI:10.1016/j.jorganchem.2006.04.030
日期:2006.8
The synthesis of cationic dirhodium(II) complexes by partial or total substitution of the acetate groups of [Rh2(OAc)4] with different homoleptic neutral bidentate ligands has been attempted. The ligand 1,8-naphthyridine gave the best results: substitution of one as well as of all four acetate ligands is possible, giving rise to mono-, di- and tetra-cationic complexes. One of the resulting tetrasubstituted
New synthesis of α-benzylaldehydes from 2-(dimethylphenylsilylmethylene)alkanals by fluoride promoted phenyl migration
作者:Laura Antonella Aronica、Francesca Morini、Anna Maria Caporusso、Piero Salvadori
DOI:10.1016/s0040-4039(02)01178-4
日期:2002.8
α-Benzyl aldehydes are prepared from easily available β-silylalkenals and fluoride reagents, under mild experimental conditions; the reaction occurs instantaneously with almost quantitative yields. A plausible mechanism is suggested, which involves a 1,2-phenylmigrationfrom the silicon to the adjacent carbon atom.
Solvated rhodium atoms, prepared by the metal vapour synthesis technique, promote the silylformylaton reaction of variously substituted alkynes (RRCH)-R-1-C-2(CH2)(n)C equivalent to CH, with catalytic activities comparable with and even higher than more common species such as Rh-4(CO)(12). Z-Silylalkenals are exclusively formed in high yields (60-95%) indicating syn addition both of CO and of the silane (Me2PhSiH) to the triple bond, The chemoselectivity of the process (silylformylation vs. hydrosilylation) is highly affected by the amount of catalyst employed (mmol of Rh species with respect to the alkyne reagent), by the steric requirements of the acetylenic substrates and by the hydrosilane/alkyne molar ratio. When optically active acetylenes are treated in the presence of Me2PhSiH under carbon monoxide pressure, the silylformylation reaction occurs with total retention of stereochemistry of the stereogenic centre, even if it is at the alpha -position of the unsaturated moiety, to afford enantiomerically enriched beta -silylalkenals.
Rhodium-catalyzed intermolecular silylcarbamoylation of acetylenic bonds
作者:Isamu Matsuda、Kiyoshi Takeuchi、Kenji Itoh
DOI:10.1016/s0040-4039(99)00200-2
日期:1999.3
alpha,beta-Unsaturated amides are readily formed by silylcarbamoylation of an acetylenic bond which is accomplished intermolecularly by a one-pot reaction of four components, an alkyne, a hydrosilane, an amine, and CO in the presence of a catalytic amount of Rh-4(CO)(12). (C) 1999 Elsevier Science Ltd. All rights reserved.