Intramolecular Dehydrogenative Coupling of sp<sup>2</sup> C–H and sp<sup>3</sup> C–H Bonds: An Expeditious Route to 2-Oxindoles
作者:Santanu Ghosh、Subhadip De、Badrinath N. Kakde、Subhajit Bhunia、Amit Adhikary、Alakesh Bisai
DOI:10.1021/ol302767w
日期:2012.12.7
An intramolecular-dehydrogenative-coupling (IDC) using "transition-metal-free" oxidation conditions has been achieved to synthesize a variety of 2-oxindoles bearing an all-carbon quaternary stereogenic center at the benzylic position. The methodology involves a one-pot C-alkylation of beta-N-arylamido esters (3, 6) with alkyl halides using potassium tert-butoxide concomitant with a dehydrogenative coupling. A radical-mediated pathway has been tentatively proposed for the oxidative process.
DDQ-mediated Direct Intramolecular-Dehydrogenative-Coupling (IDC): Expeditious Approach to the Tetracyclic Core of Ergot Alkaloids
An efficient route to 2-oxindoles bearing an all-carbon quaternary center at the pseudobenzylic position has been developed via a DDQ-mediated Intramolecular-Dehydrogenative-Coupling (IDC). The methodology involves a one-pot C-alkylation of beta-N-arylamido esters (7) concomitant with dehydrogenative-coupling in the presence of stoichiometric amount of DDQ. A tentative mechanistic route has been proposed for the oxidative coupling. The methodology provides a two-step entry to the ergoline structure of ergot alkaloids.
Preparation of 3-Alkylated Oxindoles from N-Benzyl Aniline via a Cu(II)-Mediated Anilide Cyclization Process
作者:Pugh, David S.、Taylor, Richard J.K.
DOI:10.15227/orgsyn.089.0438
日期:——
Synthesis of 2-oxindoles via 'transition-metal-free' intramolecular dehydrogenative coupling (IDC) of sp<sup>2</sup> C–H and sp<sup>3</sup> C–H bonds
benzylic position has been achieved via a 'transition-metal-free' intramolecular dehydrogenative coupling (IDC). The construction of 2-oxindole moieties was carried out through formation of carbon-carbon bonds using KOt-Bu-catalyzed one pot C-alkylation of beta-N-arylamido esters with alkyl halides followed by a dehydrogenative coupling. Experimental evidences indicated toward a radical-mediated path for
Preparation of 3-Alkyl-Oxindoles by Copper(II)-Mediated C-H, Ar-H Coupling Followed by Decarboxyalkylation
作者:Richard Taylor、David. Pugh、Johannes Klein、Alexis Perry
DOI:10.1055/s-0029-1219392
日期:2010.4
A novel route for the conversion of anilides into 3-alkyl-oxindoles is described in which a copper(II)-mediated cyclization process is followed by an acid-mediated decarboxyalkylation. Scope and limitation studies are reported together with a telescoped variant which incorporates in situ N-deprotection.