2-Methylene-1,3-dioxepane

This indicates the possibility of making addition polymers biodegradable by the introduction of ester linkages in to the backbone. Since the free radical ring-opening polymerization of cyclic ketene acetals, such as 2-methylene-1,3-dioxepane (1, Scheme I), made possible the introduction of ester groups into the backbone of addition polymers, this appeared to be an attractive method for the synthesis of biodegradable addition polymers. 

The dehydration of aldoximes with 2-methylene-1,3-dioxepane has been found to proceed smoothly in the presence of a catalytic amount of scandium(IH) triflate to give the corresponding nitriles. The authors608 proposed that coordination of Sc(OTf)3 to the oxygen atom of the 1,3-dioxepane ring induces C—O bond cleavage to form a cationic... 

Acid-induced ring opening of 2-methylene-1,3-dioxepanes leads to monoacetylated diols (45) with virtually quantitative monoacetylation selectivity (Scheme 6) <95JOC5729>. Acid-catalyzed addition of methanol gives cyclic orthoacetates <86TL1587>. 

Methylene-1,3-dioxepane (28) has also found application in 1,3-dipolar and hetero-Diels-Alder cycloadditions in solvent-free conditions under microwave irradiation to give products (47), (48), and (49) (Scheme 7) <94JCS(Pl)3595>. Treatment with phenyl isocyanate gives Spiro compound (46)... 

Addition of methanol to 2-methylene-1,3-dioxepane (28) leads to the corresponding seven-membered cyclic orthoacetate (156) (Equation (23)) <86TL1587>, and electrochemical reduction of 1,3-dioxepan-2-one (157) in an electrolyte containing alkali metal ions affords orthoester derivatives (158), useful for stabilizing /i-doped polyacetylene as the anode-active material of a battery (Equation (24)) <85JAP(K)60I2628I>. 

Poly(5,6-benzo-2-methylene-1,3-dioxepane-co-jV-isopropylacrylamide) water 2007REN... 

It was also reported recently that a controlled free-radical ring-opening polymerization and chain extension of the living polymer was achieved in a polymerization of 2-methylene-1,3-dioxepane in the presence of 2,2,6,6-tetramethyl-l-piperidinyloxy free radical (TEMPO) [232] The reaction was initiated with di-ferf-butyl peroxide at 125°C... 

Scheme 2.1 Radical ring-opening polymerization of 2-methylene-1,3-dioxepane (MDO) gives an aliphatic polyester (polycaprolactone). The same polymer is conventionally made by ring-opening polymerization of the cyclic ester (e-caprolactone), an isomer of MDO.

Scheme 2.3 Radicai ring-opening polymerization (RROP) mechanism of cyclic ketene acetals initiated by a radicai 2-methylene-1,3-dioxepane (MDO) is taken as an example.

Scheme 2.7 Simple mixing and heating led to a degradable bio-based polymer by reaction of 2-methylene-1,3-dioxepane and Tulipalin-A. (Reproduced from Ref. [40].)...

Z., and Wu, S.R. (1982) Free radical ring opening polymerization of 4,7-dimethyl-2-methylene- 1,3-dioxepane and 5,6-benzo-2 methylene-l,3-dioxepane. Macromolecules, 15, 711 (c) Liu,... 

Roberts, G.E., Coote, ML., Heuts, J.P.A., Morris, L.M., and Davis, X.P. (1999) Radical ring-opening copolymerization of 2-methylene 1,3-dioxepane and methyl methacrylate experiments originally designed to probe the origin of the penultimate unit effect. Macromolecules,... 

Synthesis and enzymatic degradation of 2 methylene-1,3-dioxepane and methyl acrylate copolymers. J. Polym. 

Telechelic polystyrene and polyethylene containing a hydroxyl and a carboxylic end group are obtained by copolymerizing a small quantity of 2-methylene-1,3-dioxepane with a large quantity of st5Tene or ethylene, and then hydrolyzing the resulting polymers (reactions 10 and 11). 

PCL can also be obtained by free radical polymerization of 2-methylene-1,3-dioxepane initiated with AIBN. However, this reaction pathway is not of great importance except in the case of the synthesis of some copolymers. 

Radical ring-opening polymerization has been essentially developed by Bailey et al. in the mid-80s. ° With appropriate monomers such as cyclic ketene acetals, the method leads to polyesters, while keeping all the advantages of a free-radical polymerization process. With NMP, however, results are very scarce and only TEMPO was used so far in the polymerization of 2-methylene-1,3-dioxepane initiated by di-tert-butyl peroxide at 125... 

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