title: Organocatalyzed step-growth polymerization through desymmetrization of cyclic anhydrides: synthesis of chiral polyesters.
abstract: The polymerization of prochiral bis-anhydrides with diols catalyzed by a cinchona alkaloid was shown to provide chiral polyesters in good yields and with high levels of stereocontrol. The structures of the polyesters were determined by (1) H and (13) C NMR analyses, whereas their size was estimated by both size-exclusion chromatography (SEC) and MALDI-TOF mass spectrometry, which indicated that moderate degrees of polymerization were attained through this step-growth polymerization. The enantioselectivity of the process was evaluated by using chiral HPLC analysis of the bis-lactones resulting from a controlled chemoselective degradation of the polyesters. The best stereocontrol was reached for oligomers formed from bis-anhydride and diol monomers bearing rigid aromatic spacers between the reactive functional groups. In this case, average enantioselectivities were comparable to those observed during ring-opening of simple anhydrides with similar alcohols. In contrast, the use of more flexible spacers between reactive entities generally led to lower levels of stereocontrol.
authors: Université de Bordeaux, Institut des Sciences Moléculaires (ISM), UMR-CNRS 5255, 351, Cours de la Libération, 33405 Talence Cedex (France).
authors: Anthony
authors: A
authors: Martin
authors: Frédéric
authors: F
authors: Robert
authors: Daniel
authors: D
authors: Taton
authors: Henri
authors: H
authors: Cramail
authors: Jean-Marc
authors: JM
authors: Vincent
authors: Yannick
authors: Y
authors: Landais
mesh_terms: D000812:Anhydrides / Q000737:chemistry*; D002384:Catalysis; D011091:Polyesters / Q000138:chemical synthesis* / Q000737:chemistry; D058105:Polymerization; D013237:Stereoisomerism
chemical_list: D000812:Anhydrides; D011091:Polyesters
keywords: anhydrides; desymmetrization; enantioselectivity; organocatalysis; polyesters; polymerization