Silver-Promoted, Palladium-Catalyzed Direct Arylation of Cyclopropanes: Facile Access to Spiro 3,3′-Cyclopropyl Oxindoles
摘要:
The Pd-catalyzed, Ag(I)-mediated intramolecular direct arylation of cyclopropane C H bonds is described. Various spiro 3,3'-cyclopropyl oxindoles can be obtained in good to excellent yields from easily accessible 2-bromoanilides. The kinetic isotope effect was determined and epimerization studies were conducted, suggesting that the formation of a putative Pd-enolate is not operative and that the reaction proceeds via a C-H arylation pathway.
Domino Corey–Chaykovsky Reaction for One-Pot Access to Spirocyclopropyl Oxindoles
作者:Saumen Hajra、Sayan Roy、SK Abu Saleh
DOI:10.1021/acs.orglett.8b01840
日期:2018.8.3
The development of the sequential Corey–Chaykovsky reactions of isatins, spiroepoxy-, or spiroaziridine oxindoles with sulfur ylide has led to the discovery of a unique reaction mode that allows easy and direct one-pot access to a range of spirocyclopropyl oxindoles.
The synthesis of spirooxindoles fused with cyclopropanes from carbamoyl chlorides, via methine C(sp3)–H activation, is reported. The regioselectivity of C–H activation in the presence of competitive C–H bonds at the appropriate position was investigated under the optimized conditions.
We have demonstrated a Pd(0)-catalyzed Heck/C(sp3)–Hactivationcascade for the synthesis of spirocyclopropyloxindoles in high yields from easily accessible ortho-bromoacrylamides. The formation of spirocyclopropyloxindole is guided by an unconventional four-membered palladacycle through C(sp3)–Hactivation. The reaction exhibits a wide range of substrate scope and operates efficiently with a mere