Cis, Isotactic Selective ROMP of Norbornenes Fused with N-Arylpyrrolidines. Double Stranded Polynorbornene-Based Ladderphanes with Z-Double Bonds

Abstract

Upon treatment with a molybdenum-carbene with bidentate substituted biaryl-o,o′-diphenoxide ligand 12, norbornene fused with N-aryl-endo-pyrrolidine 9a undergoes ROMP to give exclusively polynorbornene with cis, isotactic-selectivity. Bis(norbornenes) connected with ferrocene 18 or benzene 20 linkers yield the corresponding double-stranded ladderphanes 19 and 21, respectively with isotactic stereochemistry having all double bonds in Z-configuration. Like the corresponding ladderphanes with E-double bonds, ladderphane 19 also assembles on HOPG to give a highly ordered two-dimensional array as revealed by STM images.