Causation in a cascade: the origins of selectivities in intramolecular nitrone cycloadditions.
The factors controlling chemo-, regio-, and stereoselectivity in a cascade of reactions starting from a bis(cyanoalkenyl)oxime and proceeding via nitrone cycloadditions have been unraveled through a series of density functional theory calculations with several different functionals. Both kinetic and thermodynamic control of the reaction cascade are important, depending upon the conditions. Kinetic control was analyzed by the distortion/interaction model and found to be dictated by differences in distortions of the cycloaddends in the transition states. A new mechanism competing with that originally proposed in the application of these reactions to the histrionicotoxin synthesis was discovered in these studies.
School of Chemistry, University of Melbourne, VIC 3010, Australia. ekrenske@unimelb.edu.au
Elizabeth H
EH
Krenske
Sesil
S
Agopcan
Viktorya
V
Aviyente
K N
KN
Houk
Brian A
BA
Johnson
Andrew B
AB
Holmes
D003500:Cyclization; D008958:Models, Molecular; D009589:Nitrogen Oxides / Q000737:chemistry*; D010091:Oximes / Q000737:chemistry*; D013237:Stereoisomerism; D013816:Thermodynamics
D009589:Nitrogen Oxides; D010091:Oximes; C015388:nitrones