Tartaric-acid-derived cyclic carbonates

Scheme 11.3 Lipase-catalyzed polymerization of L-tartaric acid derive cyclic carbonate followed by deprotection of the ketal groups to give chiral, hydroxy functional polycarbonate.

One attractive feature of the 2,3-dihydroxy groups present in tartaric acid derivatives is the fact that they can be incorporated into cyclic derivatives in which the protecting group also maintains a reactive center, as already discussed in the case of the orthoester protected tartrates. Cylic carbonates and cyclic sulfur compounds of tartaric acids offer additional opportunities for exploitation of the chirality of the tartaric acids in the preparation of very useful chiral intermediates. 

Enantiomerically pure functional polycarbonate was synthesized from a novel seven-membered cyclic carbonate monomer derived from naturally occurring L-tartaric acid [99]. The ROP catalyzed by Novozym 435 was performed in bulk, at 80 °C, for 48h to afford optically active polycarbonate with M = 15500 g/mol and PDI 1.7 (Scheme 4.17). Hydroxy group functionality in the carbonate chain was achieved by deprotection of the ketal group. The polycarbonates have potential in biomedical applications. 

Wu, R., Al-Azemi, T.F., and Bisht, K.S. (2008) Functionalized polycarbonate derived from tartaric acid enzymatic ring-opening polymerization of a seven-membered cyclic carbonate. Biomacromolecules, 9 (10), 2921-2928. 

Chiral, hydroxy functional polycarbonates were prepared by the enzymatic ring opening polymerization (ROP) of a seven-membered cyclic carbonate (12) derived from L-tartaric acid (Scheme 11.3) [24]. Among others Novozym 435, PFL, and... 

Enantiomerically pure functional polycarbonate, having many potential biomedical uses, was synthesised from a novel seven-membered cyclic carbonate monomer derived from naturally occurring L-tartaric acid, using four commercially available lipases from different sources at 80 ° C, in bulk. The highest number-average MW, Mn = 15,500 g/mol, polydispersity index (PDI) = 1.7, [a]o ° = +77.8 and melting temperature (Tm) = 58.8 °C, optically active polycarbonate was obtained with lipase CALB [61]. 

Recently, Wu et have presented enzymatic polymerization of a novel seven-membered cyclic carbonate monomer, (5S,6S)-dimethyl-5,6-0-isopropylidene-l,3-dioxepin-2-one (ITC), derived from naturally occurring L-tartaric acid. The monomer was obtained in three steps (Scheme 76). 

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