Scope of Palladium-Catalyzed Alkylative Ring Opening
作者:Mark Lautens、Sheldon Hiebert
DOI:10.1021/ja037550s
日期:2004.2.1
We have explored the scope of the palladium-catalyzed nucleophilic ringopening methodology. New highly selective and highly active catalysts have been found for the ringopening of oxabenzonorbornadienes. Employing these catalysts, the addition of various alkyl nucleophiles to oxabenzonorbornadiene has been achieved. In addition, reaction of diethylzinc with [3.2.1] oxabicyclic alkenes has been accomplished
Mechanistic Studies of the Palladium-Catalyzed Ring Opening of Oxabicyclic Alkenes with Dialkylzinc
作者:Mark Lautens、Sheldon Hiebert、Jean-Luc Renaud
DOI:10.1021/ja010498k
日期:2001.7.1
The mechanism of the palladium-catalyzed ring opening of oxabicyclicalkenes with dialkylzinc has been studied. Experiments which rule out a π-allyl mechanism were carried out. Trapping carbometalated products and synthesis and successful reaction of alkyl palladium species provided strong evidence in favor of an enantioselective carbopalladation as the key step in the mechanism. The studies also suggest
Enantioselective Ring Opening of Aza and Oxabicyclic Alkenes with Dimethylzinc
作者:Mark Lautens、Sheldon Hiebert、Jean-Luc Renaud
DOI:10.1021/ol006052a
日期:2000.6.1
A system for efficient, asymmetric alkylative ringopening of azabenzonorbornadienes and [2.2.1] and [3.2.1] oxabicyclicalkenes was developed. The use of Pd(CH(3)CN)(2)Cl(2) and chiral phosphinooxazoline ligands gives the dihydronaphthalenes, cyclohexenols, and cycloheptenols in excellent yields and enantiomeric excesses.
Addition of Bifunctional Organoboron Reagents to Strained Alkenes. Carbon−Carbon Bond Formation with Rh(I) Catalysis in Aqueous Media
作者:Mark Lautens、John Mancuso
DOI:10.1021/jo049874k
日期:2004.5.1
complex to generate a functionalized organorhodium intermediate that can cyclize onto strained olefins in good to excellent yields. The catalytic system involves the use of an electron-rich, sterically bulky ligand to stabilize the organorhodium intermediate and reduce the incidence of protodeboronation in aqueous media.
Rhodium-Catalyzed Tandem Vinylcyclopropanation of Strained Alkenes
作者:Nai-Wen Tseng、John Mancuso、Mark Lautens
DOI:10.1021/ja060877j
日期:2006.4.1
This communication reports an unusual rhodium-catalyzed 1,6-addition of a dienylboronate ester to highly strained alkenes. The resulting vinylcyclopropane-fused tricyclic products were produced in moderate to good yields. Preliminary mechanistic studies are also presented.