The quantum mechanics/molecular mechanics (QM/MM) ONIOM(B3LYP:UFF) approach is applied to the study of the asymmetric carbonylative intramolecular cycloaddition of a HCC-CH2-N(Ts)-CH2-CH=CH2 enyne (Ts = tosyl) catalyzed by [(BINAP)Co-2(CO)(6)] (BINAP = (1,1'-binaphtalene)-2,2',diylbis(diphenylphosphine)). The experimental results, showing formation of the R product when the S-BINAP ligand is used, are reproduced. Comparison of the structures of the computed transition states leading to the R and S products provides a qualitative explanation for the origin of selectivity based on steric repulsions between specific substituents. (C) 2010 Elsevier B.V. All rights reserved.