Cyclic esters, ring-opening

Cyclic esters, ring-opening polymerization of, 85-87 Cyclic lactams, 174 Cyclic oligoesters, 31 Cyclic oligomers, 63, 542 formation of, 39... 

Cyclic amino-carbenes, in molybdenum carbonyls, 5, 457 Cyclic bis(phosphine) dichlorides, with iron carbonyls, 6, 48 Cyclic carbenes, as gold atom ligands, 2, 289 Cyclic carbometallation, zirconium complexes, 10, 276 Cyclic carbozirconation characteristics, 10, 276 intermolecular reactions, 10, 278 intramolecular reactions, 10, 278 Cyclic dinuclear ylides, and gold , 2, 276 Cyclic 1,2-diols, intramolecular coupling to, 11, 51 Cyclic enones, diastereoselective cuprate additions, 9, 515 Cyclic esters, ring-opening polymerization, via lanthanide catalysis, 4, 145 Cyclic ethers... 

Pitet and HiUmyer [436] formed triblock copolymers from 1,5-cycloocatadiene and OL-Lactide by combining ring opening metathesis polymerization with cyclic ester ring opening polymerization. 

Cyano compounds liquid crystals, 12, 278 in silver(III) complexes, 2, 241 Cyanocuprates, with copper, 2, 186 Cyano derivatives, a-arylation, 1, 361 Cyanosilanes, applications, 9, 322 Cyclic acetals, and Grignard reagent reactivity, 9, 53 Cyclic alkenes, asymmetric hydrosilylation, 10, 830 Cyclic alkynes, strained, with platinum, 8, 644 Cyclic allyl boronates, preparation, 9, 196 Cyclic allylic esters, alkylation, 11, 91 Cyclic amides, ring-opening polymerization, via lanthanide catalysis, 4, 145... 

The addition of nucleophiles to cyclic fluoroolefins has been reviewed by Park et al. [2 ]. The reaction with alcohols proceeds by addition-elimination to yield the cyclic vinylic ether, as illustrated by tlie reaction of l,2-dichloro-3,3-di-fluorocyclopropene Further reaction results in cyclopropane ring opening at the bond opposite the difluoromethylene carbon to give preferentially the methyl and ortho esters of (Z)-3-chloro-2-fluoroacrylic acid and a small amount of dimethyl malonate [29] (equation 8). 

Less important methods are the self condensation of w-hydroxy acid and the ring opening of lactones and cyclic esters. In self condensation of w-hydroxy acids, cyclization might compete seriously with linear polymerization, especially when the hydroxyl group is in a position to give five or six membered lactones. 

Other ring-opening copolymerizations (of, for example, the cyclic allyl sulfide 19), also yield polymers with in-chain ester groups and copolymcrizc more readily (Section 4A2.2). 

This scheme is remarkably close to the coordination insertion mechanism believed to operate in the metal alkoxide-catalyzed ring-opening polymerization of cyclic esters (see Section 2.3.6). It shares many features with the mechanism proposed above for the metal alkoxide-catalyzed direct polyesterification (Scheme 2.18), including the difficulty of defining reaction orders. 

Polyesters from the Ring-Opening Polymerization of Cyclic Esters... 

When excess amounts of the HHT of phenyl glycinate 42 were used with diphenyl phosphite, the preferred product was the novel cyclic derivative 45 (2). Presumably, ring-opening of the HHT produced intermediate 43 first, which lost an equivalent of glycinate formaldimine to give 44. The proximity of the activated phenyl carboxylate ester to the N-H in 44 presumably promoted intramolecular cyclization to 45 with loss of phenol (2). 

Various cyclic esters have been subjected to hpase-catalyzed ring-opening polymerization. Lipase catalyzed the ring-opening polymerization of 4- to 17-membered non-substituted lactones.In 1993, it was first demonstrated that medium-size lactones, 8-valerolactone (8-VL, six-membered) and e-caprolactone (e-CL, seven-membered), were polymerized by lipases derived from Candida cylindracea, Burkholderia cepacia (lipase BC), Pseudomonas fluorescens (lipase PF), and porcine pancreas (PPL). °... 

Polyester syntheses have been achieved by enzymatic ring-opening polymerization of lactide and lactones with various ring-sizes. Here, we focus not only on these cyclic esters but also other cyclic monomers for lipase-catalyzed ringopening polymerizations. Figure 8 summarizes cyclic monomers for providing polyesters via lipase catalysis. 

RING-OPENING POLYMERIZATION OF CYCLIC ESTERS 9.1.6.1 Introduction... 

The high level of interest in the ring-opening polymerization (ROP) of cyclic esters (lactones) stems from the biocompatibility and biodegradability of their polymers. Resorbable aliphatic... 

Brunelle, D. J. and Serth-Guzzo, J. Titanate-catalyzed ring-opening polymerization of cyclic phthalate ester oligomers, Polym. Prep., 40(1), 566 (1999). 

Diol monoacetates are obtained from the diols via the intermediate formation of the bromomethyl acetals and their conversion into cyclic methylene acetals, which undergo acid-catalysed ring-opening to yield the acetate ester [31]. The ring-opening is regio-specific to form the ester at the least hindered hydroxyl group. 

Lactams are cyclic amides that have several features in common with their ester counterparts (lactones). As with lactones, the ring opening of lactams should be regarded as hydration rather than hydrolysis, since lactams,... 

H-1,3-Benzoxazine-2,4(3H)-dione (7.98) is an interesting cyclic carbamate. Hydrolysis of the ester group likely yields the ring-opened carbamic acid 7.99 as an undetected intermediate, which very rapidly decarboxylates to form the product salicylamide (7.100). When the cyclic carbamate was ad-... 

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