Indolyne and aryne distortions and nucleophilic regioselectivites.
Density functional theory computations reproduce the surprisingly high regioselectivities in nucleophilic additions and cycloadditions to 4,5-indolynes and the low regioselectivities in the reactions of 5,6-indolynes. Transition-state distortion energies control the regioselectivities, activating the 5 and 6 positions over the 4 and 7 positions, leading to high preferences for 5- and 6-substituted products from 4,5- and 6,7-indolynes, respectively. Orbital and electrostatic interactions have only minor effects, producing low regioselectivities in the reactions of 5,6-indolynes. The distortion model predicts high regioselectivities with 6,7-indolynes; these have been verified experimentally. The regioselectivities found with other arynes are explained on the basis of distortion energies that are reflected in reactant geometries.
Cheong
Paul H-Y
PH
Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA.
Paton
Robert S
RS
Bronner
Sarah M
SM
Im
G-Yoon J
GY
Garg
Neil K
NK
Houk
K N
KN
D006841:Hydrocarbons, Aromatic / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry; D008956:Models, Chemical; D008958:Models, Molecular; D015394:Molecular Structure; D011789:Quantum Theory; D013237:Stereoisomerism; D013816:Thermodynamics
D006841:Hydrocarbons, Aromatic; D007211:Indoles