allyl ethyl carbonates with isocyanides in the presence of a catalytic amount of Pd(OAc)2 provided ketenimines through β‐hydride elimination of the allyl imidoylpalladium intermediates. The insertion of the isocyanide into the π‐allyl Pd complex proceeded via an unusual η1‐allyl Pd species. The resulting ketenimines were hydrolyzed to β,γ‐unsaturated carboxamides during purification by flash column chromatography
An efficient synthesis of (E)-α,β-unsaturated ketones and esters with total stereoselectivity by using chromium dichloride
作者:José M. Concellón、Humberto Rodríguez-Solla、Carmen Méjica
DOI:10.1016/j.tet.2006.01.052
日期:2006.4
(E)-α,β-Unsaturatedketones 1 or esters 2 can be obtained with complete stereoselectivity by reaction of different 2-chloro-3-hydroxy ketones 3 or esters 4 and CrCl2. A comparative study of the results of synthesis of ketones 1 with CrCl2 or samarium is performed. A mechanism to explain both β-elimination reactions has been proposed.
Stereoselective Olefination Reactions Promoted by Rieke Manganese
作者:José Concellón、Humberto Rodríguez-Solla、Vicente del Amo、Pamela Díaz
DOI:10.1055/s-0029-1216880
日期:2009.8
applied to develop a novel and direct synthesis of (E)-α,β-unsaturated esters or amides and (Z)-α,β-unsaturated α-halo esters and α-choroamides through a Mn*-mediated sequential olefination protocol of aldehydes with dichloro esters or amides and trihalo esters or trichloroamides, respectively. manganese - elimination reactions - stereoselectivity - α,β-unsaturated esters - α,β-unsaturated amides - metalation
A facile and general sequential elimination/reduction process promoted by samariumdiiodide provides an efficient method for synthesizing saturated esters or amides 3 from readily available starting materials. The reaction involves a beta-elimination of the starting 2-halo-3-hydroxyesters or -amides 1 and subsequent 1,4-reduction of the obtained alpha,beta-unsaturated esters or amides in the presence
Manganese-Promoted β-Elimination Reactions: Totally Stereoselective Synthesis of (<i>E</i>)-α,β-Unsaturated Esters
作者:José M. Concellón、Humberto Rodríguez-Solla、Vicente del Amo
DOI:10.1055/s-2005-923592
日期:——
Stereoselective β-elimination of 2-bromo-3-hydroxyesters is achieved by using non-preactivated manganese and trimethylsilyl chloride, to yield (E)-α,β-unsaturated esters with total diastereoselectivity.