1380439-64-4Relevant academic research and scientific papers
Divergent Synthetic Access to E- and Z-Stereodefined All-Carbon-Substituted Olefin Scaffolds: Application to Parallel Synthesis of (E)- and (Z)-Tamoxifens
Ashida, Yuichiro,Honda, Atsushi,Sato, Yuka,Nakatsuji, Hidefumi,Tanabe, Yoo
, p. 73 - 89 (2017)
A highly substrate-general synthesis of all-carbon-substituted E- and Z-stereodefined olefins is performed. The method comprises two sets of parallel and stereocomplementary preparations of (E)- and (Z)-α,β-unsaturated esters involving two robust and distinctive reactions: 1) stereocomplementary enol tosylations using readily available TsCl/diamine/(LiCl) base reagents, and 2) stereoretentive Negishi cross-coupling using the catalysts [Pd(dppe)Cl2] (for E) and [Pd(dppb)Cl2] (for Z). The present parallel approach is categorized as both type I (convergent approach: 16 examples, 56–87 % yield) and type II (divergent approach: 18 examples, 70–95 % yield). The obtained (E)- and (Z)-α,β-unsaturated ester scaffolds are successfully transformed into various E- and Z-stereodefined known and novel olefins (8×2 derivatization arrays). As a demonstration, application to the parallel synthesis of both (E)- and (Z)-tamoxifens, a representative motif of all-carbon-substituted olefins, is accomplished in a total of eight steps with an overall yield of 58 % (average 93 %) and 57 % (average 93 %), respectively.
Oxidative heck arylation for the stereoselective synthesis of tetrasubstituted olefins using nitroxides as oxidants
He, Zhiheng,Kirchberg, Sylvia,Froehlich, Roland,Studer, Armido
, p. 3699 - 3702 (2012/05/20)
One, two, and three! Nitroxides and dioxygen serve as oxidants in highly stereoselective oxidative Pd-catalyzed Heck arylations in which aryl boronic acids are used to synthesize triarylalkyl-substituted olefins. The reactions occur under very mild conditions at room temperature. As an example, the threefold sequential arylation of methyl acrylate is the crucial step in the stereoselective synthesis of Z-Tamoxifen.
