Predictable and regioselective insertion of internal unsymmetrical alkynes in rhodium-catalyzed cycloadditions with alkenyl isocyanates.
A regioselective, rhodium-catalyzed cycloaddition between a variety of internal, unsymmetrical alkynes is described. We document the impact of both steric and electronic properties of the alkyne on reaction course, efficiency, and enantioselectivity. The substituent that better stabilizes a positive charge or the larger group, all else being equal, inserts distal to the carbonyl moiety in a predictable and controllable fashion. The reaction scope is broad and the enantioselectivities are high, providing an "instruction manual" for substrate choice when utilizing this reaction as a synthetic tool.
Friedman
Rebecca Keller
RK
Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
Rovis
Tomislav
T
D000480:Alkynes / Q000737:chemistry*; D002384:Catalysis; D004583:Electrons; D017953:Isocyanates / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism; D013379:Substrate Specificity
D000480:Alkynes; D017953:Isocyanates; D012238:Rhodium