Using nucleophilic substitution reactions to understand how a remote alkyl or alkoxy substituent influences the conformation of eight-membered ring oxocarbenium ions.
[reaction: see text] A remote alkoxy substituent strongly stabilizes one particular conformer of an eight-membered ring oxocarbenium ion by a through-space electrostatic effect. X-ray crystallographic analysis of a crystalline derivative proves that kinetically controlled nucleophilic substitution favors the 1,4-trans product. Nucleophilic substitution of the corresponding alkyl-substituted acetate, however, is unselective. A computational model has been developed and experimentally validated to predict the low-energy conformers of C3-, C4-, or C5-alkyl- or alkoxy-substituted eight-membered ring oxocarbenium ions.
Chamberland
Stephen
S
Department of Chemistry, University of California-Irvine, Irvine, California 92697-2025, USA.
Woerpel
K A
KA
D000085:Acetates / Q000737:chemistry; D000478:Alkylation; D003500:Cyclization; D006838:Hydrocarbons; D007477:Ions / Q000737:chemistry; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry*; D008956:Models, Chemical; D035964:Oxocins / Q000737:chemistry*; D013237:Stereoisomerism
D000085:Acetates; D006838:Hydrocarbons; D007477:Ions; D035964:Oxocins; C030011:carbene; D008697:Methane