Chemoselective synthesis of allyltrimethylsilanes by cross-coupling of vinyl triflates with tris((trimethylsilyl)methyl)aluminum catalyzed by palladium(0)
Rhodium-Catalyzed Tandem Cyclopropanation/Cope Rearrangement of 4-Alkenyl-1-sulfonyl-1,2,3-triazoles with Dienes
作者:Brendan T. Parr、Huw M. L. Davies
DOI:10.1002/anie.201304310
日期:2013.9.16
Take your pick…︁ A practical method for the synthesis of structurally diverse rhodium vinylcarbenes from stable 1‐sulfonyl‐1,2,3‐triazole precursors has been developed. The reaction is general for a broad range of 4‐alkenyl triazoles and dienes, enabling the stereoselective synthesis of a variety of polycyclic imines, which are readily converted into amines or aldehydes in a one‐pot process.
efficient construction of a series of chiral phenanthrenone derivatives bearing an all‐carbon quaternary center. The effectiveness of this method in the synthesis of terpenes and steroids was demonstrated by a highly efficient synthesis of a kaurene intermediate, the facile construction of the skeleton of the anabolic steroid boldenone, and the enantioselective totalsynthesis of the antimicrobial diterpene
Strictly regio-controlled method for α-alkenylation of cyclic ketones via palladium-catalyzed cross coupling
作者:Ei-ichi Negishi、Zbyslaw R. Owczarczyk、Douglas R. Swanson
DOI:10.1016/0040-4039(91)80010-4
日期:1991.1
Cyclic α-iodoenones and α-triflyloxyenones, but not α-bromoenones, smoothly react with alkenylzinc and related derivatives in the presence of a catalytic amount of a palladium-phosphine complex, such as Pd(PPh3)4 or Cl2Pd(PPh3)2 treated with n-BuLi (2 equiv), to give α-alkenylenones which can be conjugately reduced to the corresponding α-alkenyl ketones with complete retention of both enone regiochemistry
Molecular Oxygen as a Redox Catalyst in Intramolecular Photocycloadditions of Coumarins
作者:Darius Paul Kranz、Axel Georg Griesbeck、Ronald Alle、Raul Perez-Ruiz、Jörg Martin Neudörfl、Klaus Meerholz、Hans-Günther Schmalz
DOI:10.1002/anie.201201222
日期:2012.6.11
Oxygen as a catalyst! While oxygen is usually excluded in nonoxidative photochemical reactions, the photocycloaddition of 3‐(alk‐4‐en‐1‐yl)‐substituted coumarins greatly benefits from the presence of O2, which was shown to act as a redoxcatalyst, preferentially in combination with the common antioxidant 3,5‐di‐tert‐butyl‐4‐hydroxytoluene (BHT).
Palladium-catalyzed coupling of arylstannanes with organic sulfonates: a comprehensive study
作者:Vittorio Farina、Bala Krishnan、Daniel R. Marshall、Gregory P. Roth
DOI:10.1021/jo00072a028
日期:1993.9
The effect of ligands and lithium chloride on the rates of the palladium catalyzed coupling between organic triflates and arylstannanes was studied. The dependence of the rate on the ligand is similar to the one previously reported for the coupling of vinylstannanes, but in the present case triphenylarsine is shown to be superior to both triphenylphosphine and tri(2-furyl)phosphine. The effect of added chloride is complex and varies depending on solvent and ligand used. Ortho-substituted arylstannanes tend to transfer alkyl moieties to a substantial extent , and therefore rates and efficiencies of aryl vs alkyl transfer were quantitated. When ortho substituents that are potentially coordinating to tin are used, no rate acceleration in the alkyl transfer process was observed, which is in contrast with two recently reported studies that suggest nucleophilic assistance at tin to be important in the transmetalation step. An important side reaction in the coupling of poorly reactive vinyltriflates and most aryltriflates is the Pd-induced homocoupling of the stannane to form biaryls. The experimental factors that control this process were evaluated.