Divinyl ester

Divinyl esters reported first by us are efficient monomers for polyester production under mild reaction conditions. In the lipase PF-catalyzed polymerization of divinyl adipate and 1,4-butanediol in diisopropyl ether at 45°C, a polyester with molecular weight of 6.7 x 10 was formed, whereas adipic acid and diethyl adipate did not afford the polymeric materials under similar reaction conditions (Scheme 3). 

Aromatic polyesters were efficiently synthesized from aromatic diacid divinyl esters. Lipase CA induced the polymerization of divinyl esters of isoph-thalic acid, terephthalic acid, and p-phenylene diacetic acid with glycols to give polyesters containing aromatic moiety in the main chain. The highest molecular weight (7.2 x 10 ) was attained from a combination of divinyl isophthalate and 1,10-decanediol. Enzymatic polymerization of divinyl esters and aromatic diols also afforded the aromatic polyesters. ... 

A combinatorial approach for biocatalytic production of polyesters was demonstrated. A library of polyesters were synthesized in 96 deep-well plates from a combination of divinyl esters and glycols with lipases of different origin. In this screening, lipase CA was confirmed to be the most active biocatalyst for the polyester production. As acyl acceptor, 2,2,2-trifluoroethyl esters and vinyl esters were examined and the former produced the polymer of higher molecular weight. Various monomers such as carbohydrates, nucleic acids, and a natural steroid diol were used as acyl acceptor. 

The Lewis acid-catalyzed 1,3-migration of divinyl esters allows the formation of 1,3-butadienes, which can undergo cycloaddition. In this respect, Dai and coworkers described a rearrangement of the divinyl alkoxyacetate 1-203 followed by a Diels-Alder reaction with a dienophile such as maleic anhydride 1-204 in the presence of catalytic amounts of Ln(fod)3 to produce 1-205 in up to 61 % yield (Scheme 1.47) [53],... 

Catalytic site of lipase is known to be a serine-residue and lipase-catalyzed reactions are considered to proceed via an acyl-enzyme intermediate. The mechanism of lipase-catalyzed polymerization of divinyl ester and glycol is proposed as follows (Fig. 3). First, the hydroxy group of the serine residue nucleophilically attacks the acyl-carbon of the divinyl ester monomer to produce an acyl-enzyme intermediate involving elimination of acetaldehyde. The reaction of the intermediate with the glycol produces 1 1 adduct of both... 

Fig. 3. Proposed mechanism of polymerization of dicarboxylic acid divinyl ester and glycol through lipase catalysis...

Polyesters containing aromatic moiety in the main chain were synthesized by lipase CA-catalyzed polymerization of dicarboxylic acid divinyl esters and gly-... 

The formation of 1.4-benzendicarboxylic acid divinyl ester is also a result of a previous type of reaction as shown below ... 

In the case of polyester synthesis from divinyl esters, hydrolysis of the vinyl end group partly took place, resulting in the limitation of the polymer growth.201 A mathematical model showing the kinetics of the polymerization predicts the product composition. On the basis of these data, a batch-stirred reactor was designed to minimize temperature and mass-transfer effects.202 The efficient enzymatic production of polyesters was achieved using this reactor poly(l,4-butylene adipate) with Mn 2 x 104 was synthesized in 1 h at 60 °C. 

In addition the Novozym 435-catalyzed bulk polymerization of divinyl adipate and 1,4-butanediol was reported [44]. The highest M, =23 236 in 98.3% yield was obtained after 72 h polymerization at 50 °C. It was found that the product molecular weight was decreased when the reaction was conducted without taking proper precautions to exclude water in reactions that can hydrolyze reactive divinyl ester groups. They also found excellent agreement between their experimental data and that predicted by a mathematical model [66]. 

Scheme 4.9 Lipase-catalyzed condensation polymerization of various divinyl esters with diols of varying length.

Jennings strategy for obtaining the macrolide skeleton was Yamaguchi esterification and ring closing metathesis (RCM) with 175 and 176 (Scheme 36). Construction of the key 2,6-cis-tetrahydropyran in 176 was carried out via diastereoselective axial reduction of an oxonium cation. The precursor, a pyranone, was prepared via RCM of divinyl ester 177. An asymmetric center was made by Brown s asymmetric allylation. 

---