Copper-catalysed approach to spirocyclic oxindoles via a direct C–H, Ar-H functionalisation
摘要:
A practical and efficient entry to spirocyclic oxindoles from readily accessible anilide precursors, using only catalytic amounts of an inexpensive copper salt together with air as the sole re-oxidant, is described. In addition to providing access to a broad range of spiro-oxindole products, the utility of this method is demonstrated in a formal synthesis of the natural product, horsfiline. (C) 2012 Elsevier Ltd. All rights reserved.
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.
Copper-catalysed approach to spirocyclic oxindoles via a direct C–H, Ar-H functionalisation
作者:Catherine L. Moody、Vilius Franckevičius、Pauline Drouhin、Johannes E.M.N. Klein、Richard J.K. Taylor
DOI:10.1016/j.tetlet.2012.01.120
日期:2012.4
A practical and efficient entry to spirocyclic oxindoles from readily accessible anilide precursors, using only catalytic amounts of an inexpensive copper salt together with air as the sole re-oxidant, is described. In addition to providing access to a broad range of spiro-oxindole products, the utility of this method is demonstrated in a formal synthesis of the natural product, horsfiline. (C) 2012 Elsevier Ltd. All rights reserved.
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