C1 polymerisation and related C–C bond forming ‘carbeneinsertion’ reactions

Abstract

In this critical review we summarise the currently available 'C1 polymerisation' techniques as valuable alternatives for 'C2 polymerisation' in the preparation of saturated main-chain carbon-based polymers. C1 polymerisation involves the growth of polymers from monomers delivering only one functionalised carbon unit (C1 monomers; typically 'carbene precursors') in each chain-growth step, which contrasts with common polymerisation of C=C bond containing substrates (C2 monomers). In the general introduction (section 1) we comment on the availability of C1 monomers and the most important differences between C1 and C2 polymerisation techniques, highlighting the opportunities provided by C1 polymerisation to prepare new polymer structures. In section 2 we describe several Lewis acid mediated C1 polymerisation reactions based on diazocompounds and sulfur ylides as C1 monomers. Some of these are 'living polymerisation' reactions which allow the synthesis of functional telechelic block-copolymers and polymethylenic homo-polymers with a wide variety of different functional end-groups at both polymer chain-ends in a controlled fashion. Miscellaneous related reactions of other C1 monomers are described in section 3. Transition metal mediated C1 polymerisation methods in section 4 allow the polymerisation of polar functionalised C1 monomers. Several homogeneous and heterogeneous catalysts are capable of producing polymers from a variety of diazo compounds, some of which even allow the formation of stereoregular polar functionalised polymers (which is a major challenge in traditional olefin polymerisation). An overview of the current state-of-the art, challenges and opportunities, as well as an overview of the available mechanistic information (sections 4 and 5) is provided. Some related C-C bond forming reactions proceeding via (migratory) carbene insertion (section 6) are also discussed (106 references).

Photocatalytic Reaction of Diazo Compounds with Aldehydes

“…Pyrrolidine-catalyzed reactionf urnished product 10 in av ery low yield, opposite to most enamine-iminiumc atalyzed reactions (entry 1). [34] However, less basic secondary, cyclica mines were quite effective( entries [3][4][5][6][7][8]. The superiority of six-membered, secondary amines over pyrrolidine suggests that nucleophilicity of the nitrogen could play ar ole,a st he highest yieldsw ere obtained for aminesw ith extra heteroatoms (oxygen or nitrogen).…”

Recent Developments in Pd‐Catalyzed Reactions of Diazo Compounds

“…For polymerization with diazo compounds as monomers, polymers with backbones consisting of one-carbon units will be generated. [20][21][22] This type of polymerization is fundamentally different from traditional vinyl polymerization, which generally produce polymers containing carbon-carbon single-bond units. The polymerization of α-diazocarbonyl compounds has attracted attention very recently, although polymerization of the less stable diazoalkanes has been known for a long time.…”

Synthesis of polymers with densely-grafted oligo(ethylene glycol)s by Pd-initiated polymerization of oxyethylene-containing diazoacetates

“…1,2 In this method, the polymer backbone is constructed from one carbon unit with N 2 releasing in each chain-growth step to give carbon-carbon main chain polymers possessing an ester substituent on every main chain carbon atom. 1,2 In this method, the polymer backbone is constructed from one carbon unit with N 2 releasing in each chain-growth step to give carbon-carbon main chain polymers possessing an ester substituent on every main chain carbon atom.…”