Platinum(II)-Catalyzed 1,6-Diene Cycloisomerizations: Turnover in the Absence of β-Hydride Elimination
摘要:
Electrophilic pincer-ligated Pt(II)-clications are efficient catalysts for the cycloisomerization of 1,6-dienes, initiated by alkene activation. The tridentate ligands inhibit beta-hydride elimination and thus enable cationic mechanisms that turnover by Pt(II) extrusion. PPP ligands lead to cyclopropane products, while PNP ligands provide cyclohexene products; mechanistic issues are also discussed.
a highly modular, clean, and scalable access to a broad variety of alkynyl sulfides in good‐to‐excellent yields. The utility of this protocol was showcased by the preparation of alkynyl sulfides, which are particularly difficult to obtain or simply unavailable through the existing methodologies. In addition, the synthetic method was extended to the preparation of alkynyl selenides.
Synthesis of Bi- and Tricyclic 1,2-Dihydroquinoline Derivatives from Arylamines and Alkynes by a Consecutive Zinc-Ammonium Salt Catalysis
作者:Nibadita Purkait、Siegfried Blechert
DOI:10.1002/adsc.201200155
日期:2012.8.13
cationic zinc complex and N,N-dimethylaniline hydrotrifluoromethyl sulphonate induces a multiple CC bond and CN bond formation. The one-step synthesis make highly substituted bi- and tricyclic 1,2-dihydroquinoline derivatives easily available from simple starting materials. The high yielding process consists of several simultaneous operating steps.
Synthesis of Bicyclic Pyrane Derivatives via Tungsten-Mediated [3 + 3] Cycloaddition of Epoxides with Tethered Alkynes
作者:Kuo-Hui Shen、Shie-Fu Lush、Tseng-Li Chen、Rai-Shung Liu
DOI:10.1021/jo010698e
日期:2001.11.1
Propargyltungsten compounds bearing a tethered epoxide were prepared in short steps from readily available materials. In the presence of various Lewis acids, BF(3).Et(2)O catalysts (25 mol %) most effectively promote the [3 + 3] cycloaddition of the epoxide with its tethered propargyltungsten group, delivering bicyclic pyranyltungsten compounds in reasonable yields. This cyclization proceeds highly
Gold(<scp>i</scp>)-catalysed cascade reactions in the synthesis of 2,3-fused indole derivatives
作者:Ana Gimeno、Alejandra Rodríguez-Gimeno、Ana B. Cuenca、Carmen Ramírez de Arellano、Mercedes Medio-Simón、Gregorio Asensio
DOI:10.1039/c5cc04606h
日期:——
A gold(I)-catalysed hydroaminative/arylative cascade for the efficient synthesis of a variety of indole-fused skeletons has been developed. Factors controlling the catalyst loading required in these transformations involving 1,3-unsubstituted indole intermediates...
Silylformylation – Fluoride-Assisted Aryl Migration of Acetylenic Derivatives in a Versatile Approach to the Synthesis of Polyfunctionalised Compounds
作者:Laura Antonella Aronica、Patrizio Raffa、Giulia Valentini、Anna Maria Caporusso、Piero Salvadori
DOI:10.1002/ejoc.200500883
日期:2006.4
Polyfunctionalised aldehydes and dihydropyrans are prepared from easily available functionalised 1-alkynes through a two-step silylformylation/arylmigration sequence. The silylformylation process is performed under mild experimental conditions and affords the corresponding beta-silylalkenals in high yields. The fluoride-promoted migration step occurs instantaneously with quantitative conversion. The