The regiospecific nucleophilic substitution during the ruthenium catalyzed allylicalkylation of 1,3-unsymmetrical disubstituted allylic esters was demonstrated. The nucleophile was selectively introduced at the position originally substituted with leaving group in the 2-DPPBA or ip-pybox ligated [RuCl2(p-cymene)]2 catalyzed allylicalkylation of 1,3-unsymmetrical disubstituted allylic esters. The
Catalytic Enantioselective Epoxidation of Tertiary Allylic and Homoallylic Alcohols
作者:José Luis Olivares-Romero、Zhi Li、Hisashi Yamamoto
DOI:10.1021/ja401182a
日期:2013.3.6
for the enantioselective epoxidation of both tertiary allylic and homoallylicalcoholscatalyzed by Hf(IV)-bishydroxamic acid (BHA) complexes is described. Asymmetric epoxidation, kinetic resolution, and desymmetrization have been developed, demonstrating the flexible nature of the Hf(IV)-BHA system. This is the first report in which these substrates were obtained with enantioselectivities of up to
Enantioselective Synthesis of Allylboronates Bearing a Tertiary or Quaternary B-Substituted Stereogenic Carbon by NHC-Cu-Catalyzed Substitution Reactions
作者:Aikomari Guzman-Martinez、Amir H. Hoveyda
DOI:10.1021/ja104254d
日期:2010.8.11
Allylic substitutions that afford alpha-substituted allylboronates bearing B-substituted tertiary or quaternary carbon stereogenic centers are presented. C-B bond-forming reactions, catalyzed by chiral bidentate Cu-NHC complexes, are performed in the presence of commercially available bis(pinacolato)diboron. Transformations proceed in high yield (up to >98%) and site selectivity (>98% S(N)2'), and
Stereospecific Rhodium-Catalyzed Allylic Substitution with Alkenyl Cyanohydrin Pronucleophiles: Construction of Acyclic Quaternary Substituted α,β-Unsaturated Ketones
作者:Ben W. H. Turnbull、Samuel Oliver、P. Andrew Evans
DOI:10.1021/jacs.5b10270
日期:2015.12.16
toward the synthesis of acyclic quaternary-substituted α,β-unsaturated ketones and thereby provides a new cross-coupling strategy for target directed synthesis. A particularly attractive feature with this process is the ability to directly couple di-, tri- and tetrasubstituted alkenyl cyanohydrin pronucleophiles to prepare the corresponding α,β-unsaturated ketone derivatives in a highly selective manner
Stereochemistry and Mechanism of Vinyl-migrating [1,2]-Wittig Rearrangement of<i>α</i>-Lithioalkyl Vinyl Ethers
作者:Katsuhiko Tomooka、Tadashi Inoue、Takeshi Nakai
DOI:10.1246/cl.2000.418
日期:2000.4
Enantiomerically defined α-stannylalkyl or α-methylbenzyl vinyl ethers, when treated with butyllithium, are shown to undergo the 1,2-vinyl migration to afford the allylic alcohols in almost racemic form in low or high yield, respectively, thereby proposing the radical cleavage-recombination pathway.