title: Experimental and theoretical investigations into the unusual regioselectivity of 4,5-, 5,6-, and 6,7-indole aryne cycloadditions.
abstract: The 6,7-indolyne shows remarkable regioselectivity in its cycloaddition with 2-substituted furans. Electron-donating groups give predominantly the more sterically crowded product, while electron-withdrawing groups display the opposite regioselectivity. By contrast, 4,5- and 5,6-indolynes show no regioselectivity. Optimized electronic structure calculations using the M06-2X density functional and 6-311+G(2df,p) basis set revealed that the 6,7-indolynes are highly polar structures and that their cycloadditions have substantial electrophilic substitution character that leads to the observed preference for contrasteric products.
authors: Department of Chemistry and Supercomputing Institute, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, USA.
authors: Ashley N
authors: AN
authors: Garr
authors: Diheng
authors: D
authors: Luo
authors: Neil
authors: N
authors: Brown
authors: Christopher J
authors: CJ
authors: Cramer
authors: Keith R
authors: KR
authors: Buszek
authors: David
authors: D
authors: VanderVelde
mesh_terms: D003500:Cyclization; D007211:Indoles / Q000737:chemistry*; D008962:Models, Theoretical; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D007211:Indoles