Rhodium-catalyzed [2 + 2 + 2] cycloaddition of alkenyl isocyanates and alkynes.
A rhodium(I)-catalyzed [2 + 2 + 2] cycloaddition between alkenyl isocyanates and alkynes has been developed. Heating a mixture of an alkenyl isocyanate and a symmetrical internal alkyne in the presence of [Rh(ethylene)2Cl]2/P(4-OMe-C6H4)3 in toluene delivers substituted indolizinones and quinolizinones. Depending on the substrates, a rare fragmentation of the isocyanate unit can be involved within the cycloaddition process to furnish a vinylogous amide embedded in the indolizinone.
Yu
Robert T
RT
Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA.
Rovis
Tomislav
T
D000475:Alkenes / Q000737:chemistry*; D000480:Alkynes / Q000737:chemistry*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000138:chemical synthesis*; D002384:Catalysis; D003500:Cyclization; D017953:Isocyanates / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry
D000475:Alkenes; D000480:Alkynes; D019086:Bridged Bicyclo Compounds, Heterocyclic; D017953:Isocyanates; D012238:Rhodium