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Copper‐Catalyzed C(sp 3 )–C(sp 2 ) Cross‐Coupling: Synthesis of 4‐Aryl‐2‐alkylamino‐3‐nitro‐4 H ‐chromenes
Author(s) -
Rao H. Surya Prakash,
Rao A. Veera Bhadra
Publication year - 2014
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201402003
Subject(s) - chemistry , aryl , catalysis , nitro , medicinal chemistry , alkyl , copper , stereochemistry , coupling reaction , organic chemistry
Inexpensive copper(II) acetate effectively catalyzes cross‐coupling of electron‐deficient as well as electron‐rich arylboronic acids with 4‐methylsulfanyl‐2‐alkylamino‐3‐nitro‐4 H ‐chromenes under near neutral conditions at room temp. to furnish a range of 4‐aryl‐4 H ‐chromenes. This new strategy enabled substitution of the C(4)SMe group present on a sp 3 hybridized carbon of the 4 H ‐chromenes with aryl/heteroaryl groups. Mechanistic probing revealed that the Cu I –Cu III cycle is involved in catalysis. One‐pot sequential substitution of C(4)SMe followed by C(6)Br with aryl groups has been achieved through Cu(OAc) 2 and Pd 2 (dba) 3 (Suzuki coupling) catalysis.