First Synthesis of Poly(acylmethylene)s via Palladium-Mediated Polymerization of Diazoketones

Abstract

Palladium-mediated polymerization of diazoketones (1a, 2a, 3a, 4a, and 6a) proceeded to give poly(acylmethylene)s (1b, 2b, 3b, 4b, and 6b), in which all of the main chain carbons had acyl groups. The structures of the novel polymers were characterized by NMR spectroscopy, elemental analyses, and molecular weight measurements (GPC and VPO), where the results of the elemental analyses suggested incorporation of a small amount of azo group (−NN−) into the main chain (ca. one −NN− per polymer chain). The presence of a CC double bond adjacent to the carbonyl carbon in the monomers was required for the polymerization to proceed. Palladium-mediated copolymerizations using a variety of combinations of diazoketones and ethyl diazoacetate, 8, as comonomers proceeded to give various poly(substituted methylene)s.

Carbenchemie: stereoreguläre Polymere aus Diazoverbindungen

“…[13][14][15] Die Veröffentlichung einer beispiellosen stereoselektiven Polymerisation von "Carbenen" aus Ethyldiazoacetat (EDA) zu einem hochmolekularen Poly(ethyl-2-ylidenacetat) (PEA; Schema 1 b mit X = H, Y = CO 2 Et) war kürzlich in dieser Hinsicht bahnbrechend. [ …”

Palladium-Mediated Polymerization of Bifunctional Diazocarbonyl Compounds: Preparation of Crosslinked Polymers by Copolymerization of Bi- and Monofunctional Diazocarbonyl Compounds

“…Elemental analysis of the product (C: 62.03%, H: 4.59%, N: 0.53%) indicates the presence of small amount of N, which should be ascribed to the incorporation of azo group (-N=N-) in the main chain via a mechanism proposed in our previous publication for the Pd-mediated polymerization of diazoketones. 7 Assuming that all the C content is derived from 1 0 , the composition [1 0 ]/ [-N=N-] was calculated to be 1.0:0.044 ([-N=N-] = 4.2 mol %). These results can be expected from the low polymerizability of diazoketones without a C=C at the ; -position of C=O as we reported, 7 and demonstrate that low molecular weight polymers having a pendant ferrocene on all the main chain carbon atoms can be prepared by the Pd-mediated polymerization of 1 (Scheme 2).…”

“…7 Assuming that all the C content is derived from 1 0 , the composition [1 0 ]/ [-N=N-] was calculated to be 1.0:0.044 ([-N=N-] = 4.2 mol %). These results can be expected from the low polymerizability of diazoketones without a C=C at the ; -position of C=O as we reported, 7 and demonstrate that low molecular weight polymers having a pendant ferrocene on all the main chain carbon atoms can be prepared by the Pd-mediated polymerization of 1 (Scheme 2).…”

“…crosslinked insoluble product were obtained depending on the feed ratio of [5]/ [7] (runs 8-10). The mol % values of azo group (-N=N-) listed for runs 6 and 8 show that the content is rather low in these comonomer combinations.…”

“…Cu-, 1 Pd-, 2 Rh-, 3,4 and B-mediated 5 polymerization and oligomerization have been reported for alkyl diazoacetate, which is the most common type of diazocarbonyl compound. 6 In addition, we have reported Pd-mediated polymerization of diazoketone 7,8 and diazoacetamide, 9 which can afford poly-(acylmethylene) and poly(N-substituted carbamoylmethylene), respectively, to extend the utility of the polymerization as a general method for polymer synthesis.…”