BERTZ SERIES ON THE WEISS REACTION .11. COOK SERIES ON THE WEISS REACTION .16. WEISS ENDO AND CLO[5.5.1.0.(2,6).0(10,13)]TRIDECANE-4,8,12-TRIONE - ANALYSIS OF H-1-NMR COUPLINGS IN A SYSTEM OF FUSED 5-MEMBERED RINGS

The configurational isomers of the title compounds consist of four fus ed five-membered rings. They contain tightly coupled H-1 NMR spin syst ems, which provide excellent models for establishing the relationships between coupling constants and conformation. Complete chemical shift assignments and spin-spin coupling constants are reported for the titl e compounds by using high-field (500 MHz) H-1 NMR techniques (e.g., 2D homonuclear and heteronuclear experiments, difference NOE enhancement s, and computational spin simulations). In addition to the more famili ar two- and three-bond couplings, the spectra of 1 and 2 also contain a number of long-range (four- and five-bond) couplings, which provide a stringent test of Barfield's theoretical treatment of four-bond coup lings.