Saturday, 16 April 2011

Selectivity in Garratt-Braverman Cyclization: An Experimental and Computational Study

Journal: Organic Letters, ASAP, 13 (5), pp 888–891, 2011

Authors: Manasi Maji, Dibyendu Mallick, Sayantan Mondal, Anakuthil Anoop, Subhendu Sekhar Bag, Amit Basak and *Eluvathingal D. Jemmis

Institute : *Indian Institute of Science Education and Research Thiruvananthapuram

Abstract: Bispropargyl sulfones equipped with aromatic rings of dissimilar nature were synthesized. Under basic conditions, these sulfones isomerized to the bisallenic sulfones, creating a competitive scenario between two alternate Garratt−Braverman (GB) cyclization pathways. The observed product distribution ruled out the involvement of any ionic intermediate and supported the diradical mechanism with greater involvement of the electron-rich aromatic ring via the more nucleophilic radical. DFT-based calculations supported the diradical mechanism along with the observed selectivity.

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