The deleteriouseffect of ethylenegas on the ring‐closing olefinmetathesis (RCM) for the formation of 5‐ to 8‐membered rings was investigated. Significant rate differences caused by ethylenegas were observed among the different ring‐size formation reactions. Nevertheless, the rate differences can be advantageously utilized for chemoselective RCM.
Diastereo- and Enantioselective Synthesis of Bi- and Tricyclic <i>N</i>-Heterocycle-Fused β-Lactones
作者:Weixu Kong、Daniel Romo
DOI:10.1021/acs.joc.7b02235
日期:2017.12.15
the diastereo- and enantioselectivesynthesis of N-heterocycle-fused-β-lactones from N-linked ketoacids is described. A series of bi- and tricyclic, N-heterocycle-fused, β-lactones were first synthesized in racemic fashion via the NCAL process with excellent diastereoselectivity (>19:1) utilizing 4-pyrrolidinopyridine as an effective achiral Lewis base. A catalytic, enantioselective version of this NCAL
A robust and recyclable ruthenium catalyst immobilised on polyethylene glycol
作者:Shazia Zaman、Andrew D. Abell
DOI:10.1016/j.tetlet.2009.07.022
日期:2009.9
A highly robust and recyclableHoveyda-Grubbs’ secondgeneration ruthenium type catalyst immobilised on polyethylene glycol is conveniently prepared from Grubbs’ secondgenerationcatalyst. The catalyst performs ring-closing metathesis of various di-and tri-substituted olefins efficiently in dichloromethane in air.
Catalytic and Structural Studies of Hoveyda-Grubbs Type Pre-Catalysts Bearing Modified Ether Ligands
作者:Stefano Guidone、Enguerrand Blondiaux、Cezary Samojłowicz、Łukasz Gułajski、Mariusz Kędziorek、Maura Malińska、Aleksandra Pazio、Krzysztof Woźniak、Karol Grela、Angelino Doppiu、Catherine S. J. Cazin
DOI:10.1002/adsc.201200385
日期:2012.10.8
Catalytic and crystallographic studies of Hoveyda–Grubbstypepre-catalysts M51TM and M52TM were performed. These two new instruments in the olefin metathesis catalyst toolbox were shown to be active at ambient temperature and at low loading, leading to clean formation of ring-closing, ring-closing enyne and cross metathesis products.
Regioselective Palladium-Catalyzed Formate Reduction of <i>N</i>-Heterocyclic Allylic Acetates
作者:Hsiu-Yi Cheng、Chong-Si Sun、Duen-Ren Hou
DOI:10.1021/jo0624896
日期:2007.3.1
The regioselective palladium-catalyzed formate reduction of allylicacetates in five- to eight-membered heterocycles is reported. Reduction of allylicacetates under mild conditions using allylpalladium chloride dimer, phosphines, and formic acid/triethylamine in DMF gives the exo-cyclic olefins in good regioselectivities and high yields. Synthetic application in preparing N-tosyl-3-oxo-piperidine