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Dehydrative Coupling of Benzylic Alcohols Catalyzed by Brønsted Acid/Lewis Base
Author(s) -
Böldl Marlene,
Fleischer Ivana
Publication year - 2019
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.201900965
Subject(s) - chemistry , carbocation , brønsted–lowry acid–base theory , catalysis , lewis acids and bases , lewis acid catalysis , organic chemistry , sulfonic acid , coupling reaction , stoichiometry , base (topology) , combinatorial chemistry , mathematical analysis , mathematics
Traditional cross‐coupling reactions show some disadvantages like the use of organohalides or the production of stoichiometric amounts of waste. The dehydrative homo‐ or heterocoupling of alcohols therefore arises as an interesting approach for a highly atom‐economical formation of carbon–carbon bonds, since water is produced as the only by‐product. We herein report a simple and direct, metal‐free protocol for the synthesis of olefins by applying catalytic amounts of a sulfonic acid and triphenylphosphane under air. A variety of olefins could be synthesized from benzylic alcohols under relatively mild conditions. Additionally, dehydrative hydroarylation of benzylic alcohols with electron‐rich arenes was possible by using only Brønsted acid under otherwise same reaction conditions. We could show that phosphane additives are essential to overcome oligomerization as main side reaction by the occupancy of the reactive carbocation intermediate.