Efficient and general copper catalyzed oxidative cyclization of ortho-vinylaniline has been accomplished employing N-tosylhydrazone as coupling partner. Various substituted quinoline derivatives of biological importance were achieved in good to excellent yield. The important features are the high functional group tolerates, up-gradation to gram scale synthesis and possible one-pot synthesis of quinoline from corresponding carboxaldehyde. Synthetic potential of the obtained quinoline derivatives was demonstrated through C-H bond functionalization reaction. Furthermore, preliminary mechanistic investigation revealed the possible generation of non-stabilized diazo compound and imine derivative as potential intermediates as well as copper catalyzed electrocyclic reaction and oxidative aromatization. © 2018 Elsevier Inc.

Pazhamalai Anbarasan

Department Of Chemistry

Angula Chandra Shekar Reddy

catalysis

Copper

Reaction intermediates

Annulation

ORTHO-VINYLANILINE

OXIDATIVE CYCLIZATION

quinoline

TOSYLHYDRAZONE

Cyclization

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Catalysis

Metal-catalyzed in situ functionalization of ammonium ylides has emerged as a mild and atom/step economy strategy for the construction of complex building blocks. Despite the success, these trapping reactions are limited to activated polar double bonds such as (α,β-unsaturated) carbonyl derivatives. Trapping of ammonium ylides with nonpolar double bonds, which allows the all-carbon quaternary center, is unprecedented. In this article, an efficient stereoselective palladium-catalyzed intramolecular trapping of N-ylides derived from o-vinylaniline and α-diazocarbonyl compounds has been accomplished, a carbenylative hydroamination of alkenes. The present reaction allows the synthesis of various tri- and tetrasubstituted indolines in good yield with high diastereoselectivity. Important features are the construction of two contiguous quaternary carbon centers via the formation of C-N and C-C bonds in a single operation, high diastereoselectivity, wide functional group tolerance, and high atom and step economy. A reaction mechanism has also been explored by a combination of experimental and DFT studies, which revealed the formation of N-ylide followed by cyclization through metallo-ene-type reaction involving a six-membered cyclic transition state, where the diastereoselectivity is also established. © 2017 American Chemical Society.

ACS Catalysis

Stereoselective Palladium-Catalyzed Synthesis of Indolines via Intramolecular Trapping of N-Ylides with Alkenes

Efficient palladium catalyzed aerobic oxidative cyclization of ortho-vinylanilines with isocyanides have been achieved for the synthesis of 2-aminoquinolines in good to excellent yield. Characteristic features of the method are tolerance to various functional groups, use of catalytic amount of [Pd]/base and O2, the most sustainable oxidant, gram scale synthesis and high step and atom efficiency. Control experiments suggested the formation of carbodiimide followed by electrocyclization and [1, 7]-H shift as possible pathway. Utility of the developed method was further demonstrated through synthesis of anti-depressant agent. © 2016 Printed in India.

Fulltext

Proceedings of the Indian National Science Academy

Palladium catalyzed aerobic oxidative cyclization of ortho-vinylanilines with isocyanides

An efficient cobalt(III)-catalyzed intramolecular cross-dehydrogenative C−H/N−H coupling of ortho-alkenylanilines has been developed utilizing O2as a terminal oxidant. The developed reaction tolerates various reactive functional groups and allows the synthesis of diverse indole derivatives in good to excellent yields. The method was successfully extended to the synthesis of benzofurans through the intramolecular cross-dehydrogenative C−H/O−H coupling of ortho-alkenylphenols. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Chemistry - A European Journal

Cobalt(III)-Catalyzed Intramolecular Cross-Dehydrogenative C−H/X−H Coupling: Efficient Synthesis of Indoles and Benzofurans

An efficient diastereoselective rhodium catalyzed synthesis of indolines possessing two contiguous tetrasubstituted carbon centers has been achieved with good to excellent yields using ortho-vinylanilines and iminocarbenes derived from N-sulfonyl-1,2,3-triazoles. The reaction affords excellent cis-diastereoselectivity through the initial formation of a N-ylide followed by intramolecular trapping with unactivated alkenes via an ene-type reaction with a well-organized transition state, namely intramolecular carbenylative amination of alkenes. The developed transformation was further extended to the successful synthesis of tricyclic compounds, imidazoindolines, through reduction and hypervalent iodine mediated oxidative cyclization. © 2016 The Royal Society of Chemistry.

Chemical Science

Rhodium catalyzed diastereoselective synthesis of 2,2,3,3-tetrasubstituted indolines from: N -sulfonyl-1,2,3-triazoles and ortho -vinylanilines

A general and efficient synthesis of diarylacetate, a diarylmethine derivative, was accomplished through rhodium catalyzed direct arylation of diazo compounds with arylboronic acids. The reaction tolerates various boronic acid derivatives and functional groups. Notably, chemoselective arylation of diazo compounds over other electrophiles were demonstrated. The efficacy of the developed methodology is shown by the expeditious synthesis of the core structure of diclofensine. © 2015 American Chemical Society.

Journal	Journal of Catalysis
Publisher	Academic Press Inc.
ISSN	00219517
Open Access	No