Subject succinate ester

Rizzarelli et al. [23] synthesized a series of copolymers with units of butylene succinate (BSu) and butylene adipate (BA) with different composition. The copolymers were subjected to enzymatic hydrolysis by lipase (actually two different lipase enzymes, obtained from Mucor miehei or from Rhizopus arrhizus). The degradation products were water soluble. Thus, they were injected in an LC apparatus (the column was a Cl 8) coupled with an ESI-MS. The LC trace displayed more than 20 peaks that were easily identified using MS. These are due to the monomers (BSu and BA), the dimers, the trimers, and the tetramers. LC peaks due to the oligomers rich in BA (e.g., BA3) are weak. On the other hand, LC peaks due to the oligomers rich in BSu (e.g.,BSus) are strong. The results indicate a preferential hydrolytic cleavage. In particular, succinic ester bonds are hydrolyzed faster than adipic ester bonds in BSu-BA copolyesters. 

L-dihydroxy-succinic acid (L(dexiro)-tartaric acid, CXIII). This result establishes the position of the double bond between C4 and C5 and demonstrates that C4 carries only one hydrogen atom while C5 has attached to it the enolic hydroxyl group. Treatment of the enol CXI with ethereal diazomethane gives 5-methyl-A4-D-glucosaccharo-3,6-lactone methyl ester (CXIY) which upon further methylation with silver oxide and methyl iodide yields 2,5-dimethyl-A4-D-glucosaccharo-3,6-lactone methyl ester (CXV). When the latter is subjected to ozonolysis there is formed oxalic acid and 3-methyl-L-threuronic acid (CXVI). Oxidation of this aldehydic acid (CXYI) with bromine gives rise to a monomethyl derivative (CXVII) of L-ilireo-dihydroxy-succinic acid. 

Figure. 25.3 Succinimidyl succinate-mPEG may be used to modify amine-containing molecules to form amide bond derivatives. The ester bond of the succinylated mPEG, however, is subject to hydrolysis.

Combination of the reagents TiCU, BuaN, and TMSOTf, was reported to be effective for Claisen condensation, as exemplified in Eqs (42) and (43) [129]. When acyl-oxazolidinones were subjected to reaction with TiCU and a tertiary amine, homocoupling reaction at the a-position of the acyl group took place to give succinic acid derivatives [146], The lithium enolate of an ester or amide has been alkylated with an (N,C>)-acetal in the presence of Ti(0-/-Pr)4 (Eq. 44) [147,148]. 

Peroxy esters of malonic and succinic acids have been subjected to thermal decomposition and the kinetic data are given in Table 110. A two-bond homolysis... 

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