| Abstract |
The number of CuCl units per camphor ligand in [\CuCl\(2)L](n) was extended to three or four in [\CuCl\(3)L](n) (2) or [\CuCl\(4)L](n) (1). The Hartree-Fock ab initio calculations support the polymeric structure of 1 and 2 that catalyze the cyclization of 4-pentyn-1-oic acid (A) forming 5-methylenedihydrofuran-2(3H)-one (B) and/or 2-methyl-5-oxotetrahydrofuran-2-ylpent-4-ynoate (C). The catalytic activity of 1, 2 and other polynuclear Cu(I) complexes (3-5) was evaluated under solvent free conditions and/or solution. In the absence of solvent, catalyst 2 displays the highest activity and selectivity (75.8/23.1, C to B ratio, at 5.4\% loading) while 4 reaches the highest level of A B conversion (97.5 \%) in solution. Selected reactions were followed by NMR and the kinetic constants calculated. A mechanism is proposed based on the equations used for the calculations. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 3316-3323 |
