Silver triflate catalyzed cyclopropyl carbinol rearrangement for benzo[b]oxepine and 2H-chromene synthesis

• Main Authors: Chan, Philip Wai Hong, Teo, Wan Teng, Koh, Shaun Wei Yong, Lee, Bo Ra, Ayers, Benjamin James, Ma, Dik-Lung, Leung, Chung-Hang
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2015
• Subjects: DRNTU::Science::Chemistry::Organic chemistry::Organic synthesis
• Online Access: https://hdl.handle.net/10356/105560; http://hdl.handle.net/10220/25972; http://dx.doi.org/10.1002/ejoc.201500374
• Institution: Nanyang Technological University

An efficient AgOTf-catalyzed (TfO = trifluoromethanesulfonate) cyclopropyl carbinol rearrangement for the synthesis of benzo[b]oxepines and 2H-chromenes is reported by starting from 2-[cyclopropyl(hydroxy)methyl]phenols. The reactions proved to be general in scope and furnished a range of the corresponding functionalized oxygen heterocycles. The formation of the benzo-fused six-membered adduct is proposed to result from the ring-contraction of the benzo[b]oxepine derivative. Control of the product selectivity is achievable by fine-tuning the reaction time. The catalytic synergy between the silver(I) cation and the triflate anion was essential for optimal product yields.