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Palladium‐Catalyzed Hydrobenzylation of ortho‐Tolyl Alkynyl Ethers by Benzylic CH Activation: Remarkable Alkynoxy‐Directing Effect

“…The cyclization smoothly took place to give the corresponding products 11, which upon treatment with acetic acid gave the 2alkenyl-substituted benzofurans 12 by elimination of methanol. [15] For example, cyclization of the 2,6-xylyl 2-(1-methoxycyclohexyl)ethynyl ethers 10 a (R = R' =À(CH 2 ) 5 ), 10 b (R = R' = Ph), and 10 c (R = Ph, R' = H) took place in the presence of 5 mol % of palladium catalyst to form the corresponding products (11), which readily converted into the 2-alkenyl benzofurans 12 in moderate yields over two steps. In the case of 10 c, the b-styryl-substituted benzofuran 12 c was obtained as a single isomer.…”

Palladium‐Catalyzed Hydrobenzylation of ortho‐Tolyl Alkynyl Ethers by Benzylic CH Activation: Remarkable Alkynoxy‐Directing Effect

“…The cyclization smoothly took place to give the corresponding products 11, which upon treatment with acetic acid gave the 2-alkenyl-substituted benzofurans 12 by elimination of methanol. [15] For example, cyclization of the 2,6-xylyl 2-(1-methoxycyclohexyl)ethynyl ethers 10 a (R = R' =À(CH 2 ) 5 ), 10 b (R = R' = Ph), and 10 c (R = Ph, R' = H) took place in the presence of 5 mol % of palladium catalyst to form the corresponding products (11), which readily converted into the 2-alkenyl benzofurans 12 in moderate yields over two steps. In the case of 10 c, the b-styryl-substituted benzofuran 12 c was obtained as a single isomer.…”

Concise Synthesis of α-Substituted 2-Benzofuranmethamines and Other 2-Subsituted Benzofurans via α-Substituted 2-Benzofuranmethyl Carbocation Intermediates

“…In 2002, Ukhin et al reported the synthesis of 2-methylidene­benzofurans 5 , from the cyclizaton reactions of propargyl amines 4 , prepared from aminals 8 of salicylaldehyde 9 and propargyl alcohols 10 according to Scheme . Cyclization of 4 (X = piperidino, R 3 = R 4 = Me) with either AgNO 3 (10 mol %) in MeCN at reflux temperature for 15 min or by treatment with KOH in MeOH at reflux temperature for 40 min gave 5 (R 1 /R 2 = piperidino R 4 = R 5 = Me) in yields of 63 and 74%, respectively.…”