Abstract2‐Alkylaminophenylprop‐1‐yn‐3‐ols, prepared from the lithium diisopropylamide (LDA)‐mediated 1,2‐addition of alkynes to 1‐(2‐aminophenyl) ketones, can be converted to 3,3‐disubstituted 2‐oxindoles by using silica gel in n‐hexane/ethyl acetate (20:1 v/v) as the reaction medium. The utility of the approach as a potential scale‐up strategy for the synthesis of 2‐oxindoles was exemplified by the large‐scale synthesis of one adduct in excellent yield. The synthetic applicability of this chemistry was also demonstrated by the recycling of the silica gel up to 8 times with no apparent loss of activity being observed for the same example.magnified image
Palladium-Catalyzed Chemoselective Activation of sp<sup>3</sup> vs sp<sup>2</sup> C–H Bonds: Oxidative Coupling To Form Quaternary Centers
作者:Gang Hong、Pradip D. Nahide、Uday Kumar Neelam、Peter Amadeo、Arjun Vijeta、John M. Curto、Charles E. Hendrick、Kelsey F. VanGelder、Marisa C. Kozlowski
DOI:10.1021/acscatal.9b00091
日期:2019.4.5
activation of alkyl C–H bonds vs arene C–H bonds with Pd(OAc)2 has been found to be generalizable to a number of nucleophilic substrates, allowing the formation of a range of hindered quaternary centers. The substrates share a common mechanistic path wherein Pd(II) initiates an oxidative dimerization. The resultant dimer modifies the palladium catalyst to favor activation of alkyl C–H bonds, in contrast to