Siddique Khan
Indian Institute of Technology Madras, India
Title: The mono and di-halogenation reactions of the HDDA benzynes
Biography
Biography: Siddique Khan
Abstract
The HDDA reaction forms polycyclic benzyne intermediates via [4+2] cycloaddition between tethered alkyne and 1,3-diyne, yielding complex benzenoid products after trapping reactions. We devised and developed a versatile method for crafting mono and dihaloarenes by trapping HDDA benzynes using Bismuth halides and N-halosuccinimides respectively. Here, we show how BiX3 reagents stimulate the hydrohalogenation reactions of HDDA benzynes to produce complicated aryl halides. Each of the three bismuth(III) halides, Cl-, Br-, or I-, can serve as the source for the corresponding halide. The type of substituent at the diyne terminal determines the regiochemical preference for hydrohalogenation. Natures of the linker and the BiX3 reagent have no effect on the regiochemical outcome of these reactions. This process exhibits broad substrate scope in terms of tethering units and diyne substituents, with good yields and moderate regioselectivity. Extending this, HDDA reactions with N-halosuccinimide gives vicinal di-halogenation of arenes as well as radical di-halogenation of HDDA benzynes. This presentation unveils our effort towards HDDA arynes using halogen based reagents.