N -Acyliminium ion chemistry and palladium catalysis: a useful combination to obtain bicyclic heterocycles
摘要:
By using N-acyliminium ion chemistry, several omega -propadienyllactams and a propadienyloxazolidine were prepared from N-acyliminium ion precursors and propargylsilanes. Treatment of these allene containing lactams and oxazolidinone with allyl halides or an allyl carbonate using Pd(II)-salts as the catalyst gave rise to a coupling-cyclization reaction, yielding bicyclic systems in which the allyl moiety is incorporated. With this methodology several substituted pyrrolizinones, an oxazolone and indolizinone were prepared. (C) 2001 Elsevier Science Ltd. All rights reserved.
The rates of monometallation of alkylphenylacetylenes
作者:James Y. Becker
DOI:10.1016/s0022-328x(00)84192-3
日期:1977.2
Alkylphenylacetylenes, C6H5CCCH2R, have been metallated at the propargylic positions with an excess of n-butyllithium in diethyl ether at 0°C. Mono- and di-silyl derivatives have been isolated by quenching the metallation mixtures with Me3SiCl at different times. Pseudo-first order rate constants have been calculated for the monometallation from the rate of formation of the silylated products. A Taft
Tethered NHC Ligands for Stereoselective Alkyne Semihydrogenations
作者:Felix Pape、Johannes Teichert
DOI:10.1055/s-0036-1590112
日期:2017.6
N-heterocyclic carbene (NHC) complexes have been investigated, leading to a highly Z-selective transformation. The catalyst is generated from inexpensive copper(I) chloride in situ and allows catalytic semihydrogenation down to 10 bar H2. A copper(I)-catalyzed semihydrogenation of internal alkynes has been developed. A variety of oxygen- and nitrogen-tethered N-heterocyclic carbene (NHC) complexes
摘要 已经开发了铜(I)催化的内部炔烃的半氢化反应。已经研究了多种氧和氮束缚的N-杂环卡宾(NHC)配合物,从而导致高度Z选择性的转化。该催化剂由廉价的原位氯化铜(I)生成,并允许低至10 bar H 2的催化半氢化作用。 已经开发了铜(I)催化的内部炔烃的半氢化反应。已经研究了多种氧和氮束缚的N-杂环卡宾(NHC)配合物,从而导致高度Z选择性的转化。该催化剂由廉价的原位氯化铜(I)生成,并允许低至10 bar H 2的催化半氢化作用。
Synthese regiospecifique d'allenes terminaux a partir de propargyltrimethylsilanes simples ou fonctionnels
作者:J. Pornet、D. Damour、L. Miginiac
DOI:10.1016/s0022-328x(00)99606-2
日期:1987.1
Protodesilylation of varied propargyltrimethylsilanes, using boron trifluorideacetic acid as reagent, give regiospecifically terminal allenes with very good yields. Yet, particular ω-functional propargyltrimethylsilanes may lead to vinylsilanes resulting from a ring-closing cyclisation reaction.
Propargyltrimethylsilanes as Allene Equivalents in Transition Metal-Catalyzed [5 + 2] Cycloadditions
作者:Paul A. Wender、Fuyuhiko Inagaki、Magnus Pfaffenbach、Matthew C. Stevens
DOI:10.1021/ol501114q
日期:2014.6.6
including metal-catalyzed [5 + 2] cycloadditions. We report herein that rhodium-catalyzed [5 + 2] cycloadditions of propargyltrimethylsilanes and vinylcyclopropanes provide, after in situ protodesilylation, a highly efficient route to formal allene cycloadducts. Propargyltrimethylsilanes function as safe, easily handled synthetic equivalents of gaseous allenes and hard-to-access monosubstituted allenes
Predictable and Regioselective Insertion of Internal Unsymmetrical Alkynes in Rhodium-Catalyzed Cycloadditions with Alkenyl Isocyanates
作者:Rebecca Keller Friedman、Tomislav Rovis
DOI:10.1021/ja903899c
日期:2009.8.5
A regioselective, rhodium-catalyzed cycloaddition between a variety of internal, unsymmetrical alkynes is described. We document the impact of both steric and electronic properties of the alkyne on reaction course, efficiency, and enantioselectivity. The substituent that better stabilizes a positive charge or the larger group, all else being equal, inserts distal to the carbonyl moiety in a predictable