Bond rotation dynamics of N-cycloalkenyl-N-benzyl alpha-haloacetamide derivatives.
Barriers to rotation of the N-alkenyl bond in a series of N-cycloalkenyl-N-benzyl alpha-haloacetamide derivatives have been measured by variable-temperature NMR experiments. The barriers range from 10 to 18 kcal/mol, depending on ring size and on substituents on the cycloalkene and the amide. The observed trends aid in the design of substituent combinations that provide resolvable enantiomers or diastereomers at ambient temperature. The compounds undergo 4-exo and 5-endo radical cyclizations at rates that may be faster or slower than the estimated rate of N-alkenyl bond rotation in the derived radicals, depending on the substituents.
Guthrie
David B
DB
Department of Chemistry, University of Pittsburgh, Pittsburgh Pennsylvania 15260, USA.
Damodaran
Krishnan
K
Curran
Dennis P
DP
Wilson
Paul
P
Clark
Andrew J
AJ
D000081:Acetamides / Q000737:chemistry*; D000475:Alkenes / Q000737:chemistry*; D003500:Cyclization; D007700:Kinetics; D008968:Molecular Conformation; D013816:Thermodynamics
D000081:Acetamides; D000475:Alkenes