Cyclopolymerization of dipropargylamine and dipropargylammonium bromide by transition metal catalysts

Mo(CO)6-catalyzed cyclopolymerization of diethyl dipropargylmalonate to give a polyene containing only five-membered rings

“…A possible explanation for the exclusive formation of poly(DEDPM) containing only five-membered rings is that Mo(CO) 6 , like the classical MoCl 5 system, is sterically very small compared to the well-defined alkylidene complexes, and thus makes more tenable the ␣-addition of the first triple bond.…”

“…Intramolecular cyclopolymerization of ␣,-diynes catalyzed by simple Mo(CO) 6 is unprecedented, although Mo(CO) 6 -based catalysts such as Mo(CO) 6 /Ph 2 CCl 2 /h and Mo(CO) 6 /C 6 H 5 OH/C 6 H 5 Cl have been known to be effective for intermolecular metathesis polymerization of phenylacetylene and norbornene. 17,18 Table I shows the high-yield synthesis of poly(DEDPM)s with a polydispersity (M w /M n ) range of 1.68 -2.48 and the average molecular weights reaching up to 110,000, which is among the highest in the literature.…”

“…A 50-mL three-neck flask equipped with a nitrogen inlet and a stirring bar was charged with 1.18 g (5 mmol) of DEDPM, 26.4 mg (0.1 mmol) of Mo(CO) 6 , and 20 mL of dioxane. The solution was stirred at 100°C for 48 h, during which the color of the solution turned to deep purple with the formation of viscous solid.…”

“…Mo(CO) 6 (Aldrich) was sublimed prior to use. Diethyl dipropargylmalonate was prepared according to a literature procedure.…”

“…In our recent investigations 15 on a new class of catalysts for polyacetylenes, we have serendipitously found that Mo(CO) 6 does exclusively catalyze the ␣-addition route. We now wish to report for the first time Mo(CO) 6 catalyzed cyclopolymerization of diethyl dipropargylmalonate (DEDPM) to exclusively give a polyene containing only five-membered rings.…”