Aza‐nickelacycles: An atom‐economic nickel‐catalyzedsynthesis of isoquinoliniumsalts is reported. The salts are readily reduced to the corresponding reductive homo‐coupling products and oxidized to isoquinolinones (see scheme). Isoquinolinones are important core structures for a vast number of natural products.
Synthesis of Isoquinolines and Pyridines by the Palladium/Copper-Catalyzed Coupling and Cyclization of Terminal Acetylenes and Unsaturated Imines: The Total Synthesis of Decumbenine B
作者:Kevin R. Roesch、Richard C. Larock
DOI:10.1021/jo010579z
日期:2002.1.1
have been developed. However, aryl-, vinylic-, and alkyl-substituted acetylenes undergo palladium-catalyzed coupling and subsequent copper-catalyzed cyclization in excellent yields. The totalsynthesis of the isoquinoline natural product decumbenine B has been accomplished in seven steps and 20% overall yield by employing this palladium-catalyzed coupling and cyclization methodology.
[GRAPHICS]The pinacol reaction of beta-halogenated alpha,beta-unsaturated aldehydes was promoted by titanium tetraiodide to give coupling products in good yields with high di-selectivity. Subsequent reduction with H-2/Pd-C gave saturated vic-diols in good yields. Heck coupling reaction enabled the displacement of halogens with vinyl groups without the loss of stereochemical integrities.
Synthesis of Isoquinolines and Pyridines by the Palladium-Catalyzed Iminoannulation of Internal Alkynes
作者:Kevin R. Roesch、Haiming Zhang、Richard C. Larock
DOI:10.1021/jo0105540
日期:2001.11.1
A wide variety of substituted isoquinoline, tetrahydroisoquinoline, 5,6-dihydrobenz[f]isoquinoline, pyrindine, and pyridine heterocycles have been prepared in good to excellent yields via annulation of internal acetylenes with the tert-butylimines of o-iodobenzaldehydes and 3-halo-2-alkenals in the presence of a palladium catalyst. The best results are obtained by employing 5 mol % of Pd(OAc)(2), an excess of the alkyne, 1 equiv of Na2CO3 as a base, and 10 mol % of PPh3 in DMF as the solvent. This annulation methodology is particularly effective for aryl- or alkenyl-substituted alkynes. When electron-rich imines are employed, this chemistry can be extended to alkyl-substituted alkynes. Trimethylsilyl-substituted alkynes also undergo this annulation process to afford monosubstituted heterocyclic products absent the silyl group.
Propargyl-Allenyl Isomerizations and Electrocyclizations for the Functionalization of Phosphonium Salts: One-Pot Synthesis of Polysubstituted Vinylbenzenes and Naphthalenes
作者:Guoqing Zhao、Qianyun Zhang、Hongwei Zhou
DOI:10.1002/adsc.201300573
日期:2013.11.25
AbstractPhosphonium salts are widely used in organic synthesis as the precursor of Wittig reagents but highly functionalized phosphonium salts are not readily available. We have developed a sequence of propargyl–allenyl isomerizations and electrocyclizations for the functionalization of phosphonium salts via simple starting materials, which may provide an efficient one‐pot synthesis of polysubstituted vinylbenzenes and naphthalenes.magnified image