Benzyne-Mediated Nonconcerted Pathway toward Synthesis of Sterically Crowded [5]- and [7]Oxahelicenoids, Stereochemical and Theoretical Studies, and Optical Resolution of Helicenoids
作者:Prashant M. Gawade、Vaibhav N. Khose、Purav M. Badani、Mohammed Hasan、Sandra Kaabel、Shaikh M. Mobin、Victor Borovkov、Anil V. Karnik
DOI:10.1021/acs.joc.8b02507
日期:2019.1.18
Synthesis of [5]- and [7]oxahelicenoids via Diels–Alder reaction of sterically crowded bichromenes with benzyne is presented. Studies carried out on Diels–Alder addition product establish the unusual preference for a stepwise mechanism over the concerted reaction pathway. This high yielding general synthetic protocol affords unexpected anti cycloadducts [5]- and [7]oxahelicenoids, as confirmed by crystallographic