Stereoselective Synthesis of Nipecotic Acid Derivatives via Palladium-Catalyzed Decarboxylative Cyclization of γ-Methylidene-δ-valerolactones with Imines
作者:Ryo Shintani、Masataka Murakami、Tamio Hayashi
DOI:10.1021/ol802569q
日期:2009.1.15
A new synthetic method of multisubstituted nipecotic acid (piperidine-3-carboxylic acid) derivatives has been developed by way of palladium-catalyzeddecarboxylative cyclization of γ-methylidene-δ-valerolactones with imines. By employing the diethoxyphosphinoyl group as the N-protecting group for imines, the reaction proceeds smoothly with high diastereoselectivity. The products thus obtained can be
Mechanistic Investigation of the Palladium-Catalyzed Decarboxylative Cyclization of γ-Methylidene-δ-valerolactones with Isocyanates: Kinetic Studies and Origin of the Site Selectivity in the Nucleophilic Attack at a (π-Allyl)palladium
of this selectivity is provided. The selectivity between 3 and 4 is also influenced by the nature of the nitrogen substituent on isocyanates 2, and more electron-rich substituents tend to give higher selectivity toward azaspiro[2.4]heptanones 4. These studies represent the first systematic investigation into the selectivity between terminal attack and central attack at (pi-allyl)palladium species by
Palladium-catalyzed Decarboxylative [4+1] Cyclization of γ-Methylidene-δ-valerolactones with Isocyanides
作者:Soyoung Park、Ryo Shintani、Tamio Hayashi
DOI:10.1246/cl.2009.204
日期:2009.3.5
A palladium-catalyzed decarboxylative cyclization of γ-methylidene-δ-valerolactones with isocyanides has been developed to afford conjugated cyclopentenimines under mild conditions. Some preliminary results toward the development of an asymmetric variant have also been described.
Palladium-Catalyzed Asymmetric (4 + 2) Annulation of γ-Methylidene-δ-valerolactones with Alkenes: Enantioselective Synthesis of Functionalized Chiral Cyclohexyl Spirooxindoles
作者:Zhi-Long Jia、Xian-Tao An、Yu-Hua Deng、Lin-Han Pang、Chun-Fang Liu、Le-Le Meng、Jia-Kun Xue、Xian-He Zhao、Chun-An Fan
DOI:10.1021/acs.orglett.0c03963
日期:2021.2.5
(S,S,S)-(−)-Xyl-SKP, offering a new approach for the diastereo- and enantioselective synthesis of chiral cyclohexadienone-fused cyclohexyl spirooxindoles. Significantly, three highly congested contiguous tetrasubstituted carbonatoms embedded in bispirocyclic skeleton, of which two are vicinalquaternarystereogenic centers, are forged in an effective and selective manner (up to 99% yield, up to 95%