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

Abstract

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Molybdenum imido alkylidene and tungsten oxo alkylidene N-heterocyclic carbene complexes for olefin metathesis

“…While complexes 3a, 3b, 4, 5, 8, and 9 contain two triflate groups, compound 6 contains two different anionic ligands, i.e., one triflate and one hexafluro-2-propoxide group. As found for MAP-type catalysts [14,[25][26][27][28][29][30][31][32][33][34][35][36][37][38][39], no ligand scrambling is observed. Cationic 7 is unique: it represents the first cationic Mo imido alkylidene catalyst that displays substantial olefin metathesis reactivity (vide infra).…”

“…Also, it should be regio-and stereoselective, whether in the synthesis of small molecules or polymers. Mo-and W-alkylidenes [10][11][12][13][14][15][16] clearly fulfill the requirements in terms of regio-and stereoselectivity; however, so far they are not competitive to Ru-based catalysts, which clearly outrival these group 6 metal-based catalysts in terms of functional group tolerance [1,17]. Unfortunately, the latter cannot fully compete with the high stereo-and regioselectivity of group 6 metal alkylidenes and if, often on the expense of activity/stability or functional group tolerance [18][19][20][21][22].…”

Selective ring-opening metathesis polymerization (ROMP) of cyclobutenes. Unsymmetrical ladderphane containing polycyclobutene and polynorbornene strands

“…To illustrate this, polynorbornenes and polycyclobutenes are readily obtained from the corresponding monomeric norbornene and cyclobutene derivatives under various conditions. Symmetrical DNA-like double stranded ladderphanes are conveniently synthesized from bisnorbornene [4–15] or from biscyclobutene [16] linked with a range of different rigid linkers. When a flexible linker is used, bisnorbornene derivatives undergo cascade metathetical cyclopolymerization giving the corresponding polynorbornenes with hammock-like pendants [17–18].…”

Stromaphane: A New Type of Two-dimensional Covalent Organic Framework with Subnanometric Slit-Shaped Pores

“…25 We have extensively applied ruthenium- 26 or molybdenum-based catalysts 27 for the stereoselective ring opening metathesis polymerisation (ROMP) 28 of N-arylpyrrolidenefused norbornene or cyclobutene derivatives (NB or CB) leading to the corresponding polymers, PNB and PCB, respectively. Double bonds in PNB are all in trans con guration, when the Grubbs G-I catalyst 26 is used, 28-30 and in cis form in both PNB 31 and PCB 32 upon treatment with a Schrock-Hoveyda catalyst SHMo (Figure 1b). 27 The presence of the N-aryl pyrrolidine moiety in NB and CB, is vital for the stereoselective formation of the corresponding polymers PNB and PCB.…”

“…The pendants in PNB and PCB thus obtained are all aligned towards a similar direction. [29][30][31][32][33] This kind of conformation offers a unique route to synthesise both symmetric and unsymmetrical double stranded ladderphanes (Figure 1a). [21][22][23][24] ROMPs of cyclopropene derivatives have been brie y explored.…”