Rhodium-Catalyzed Intermolecular C–H Functionalization as a Key Step in the Synthesis of Complex Stereodefined β-Arylpyrrolidines
摘要:
The synthesis of beta-arylpyrrolidines via a catalytic enantioselective intermolecular allylic C(sp)(3)-H functionalization of trans-alkenes followed by immediate reduction, ozonolysis, and then in situ diversification of the resulting cyclic hemiaminal to furnish highly substituted, stereoenriched beta-arylpyrrolidines is reported. This methodology utilizes 4-aryl-1-sulfony1-1,2,3-triazoles as carbene precursors and the dirhodium tetracarboxylate catalyst Rh-2(S-NTTL)(4). A variety of beta-arylpyrrolidines were prepared in good yields with high levels of diastereo- and enantioselectivity over four linear steps, requiring only a single purification procedure.
Transannulation of 1-Sulfonyl-1,2,3-triazoles with Heterocumulenes
作者:Stepan Chuprakov、Sen Wai Kwok、Valery V. Fokin
DOI:10.1021/ja400350c
日期:2013.3.27
reactions with isocyanates and isothiocyanates, respectively. The proposed triazole-diazoimine equilibrium results in the formation of highly reactive azavinyl metal-carbenes, which react with heterocumulenes causing an apparent swap of 1,2,3-triazole core for another heterocycle.
The rhodium(II)‐catalyzed denitrogenative coupling of N‐alkylsulfonyl 1,2,3‐triazoles with 1,3,5‐trioxane led to nine‐membered‐ringed trioxazonines in moderate‐to‐good yields. 1,3,5‐Trioxane, acting as an oxygen nucleophile, reacted with the α‐aza‐vinylcarbene intermediate, giving rise to ylide formation, which was probably the key step in the reaction. Triazoles that contained aryl substituents with
A sequential procedure for the synthesis of 2,5-disubstituted thiazoles from terminal alkynes, sulfonyl azides, and thionoesters is reported. A copper(I)-catalyzed 1,3-dipolar cycloaddition of terminal alkynes with sulfonyl azides affords 1-sulfonyl-1,2,3-triazoles, which then react with thionoesters in the presence of a rhodium(II) catalyst. The resulting 3-sulfonyl-4-thiazolines subsequently aromatize
A syn‐selective aza‐aldol reaction of boron aza‐enolates, generated from N‐sulfonyl‐1,2,3‐triazoles and 9‐BBN‐H, is reported. It provides a sequential one‐pot procedure for the stereoselective construction of 1,3‐amino alcohols, having contiguous stereocenters, starting from terminal alkynes.
Catalytic Asymmetric Synthesis of Pyrroloindolines via a Rhodium(II)-Catalyzed Annulation of Indoles
作者:Jillian E. Spangler、Huw M. L. Davies
DOI:10.1021/ja4025337
日期:2013.5.8
Herein we report the synthesis of pyrroloindolines via a catalytic enantioselective formal [3+2] cycloaddition of C(3)-substituted indoles. This methodology utilizes 4-aryl-1-sulfonyl-1,2,3-triazoles as carbenoid precursors and the rhodium(II)-tetracarboxylate catalyst Rh2(S-PTAD)4. A variety of aryl-substituted pyrroloindolines were prepared in good yields and with high levels of enantioinduction