Controlled synthesis of 2- and 3-substituted benzo[b]furans.
A controlled regioselective synthesis of either C-2 or C-3 substituted benzo[b]furans from readily accessible 1-(2-hydroxyphenyl)-2-chloroethanones is described. Addition of a range of Grignard reagents to the α-chloro ketones generates alkoxide intermediates, which can form either 2-substituted benzo[b]furans via a [1,2]-aryl migration or 3-substituted benzo[b]furans via a direct cyclization and dehydration sequence. A temperature-dependent [1,2]-aryl migration mechanism for the formation of 2-substituted benzo[b]furan is proposed.
Pei
Tao
T
Department of Process Chemistry, Merck Research Laboratories, P.O. Box 2000, Rahway, New Jersey 07065, United States. tao_pei@merck.com
Chen
Cheng-yi
CY
DiMichele
Lisa
L
Davies
Ian W
IW
D001572:Benzofurans / Q000138:chemical synthesis*; D003500:Cyclization; D015394:Molecular Structure
D001572:Benzofurans