Hydrolases Part I: Enzyme Mechanism, Selectivity and Control in the Synthesis of Well-Defined Polymers. In: Palmans ARA, Heise A, editors. Enzymatic Polymerisation. Berlin: Springer Berlin Heidelberg; 2011. pp. 55-78. [DOI: 10.1007/12_2010_86]

Enantioselective ene-reduction of E-2-cyano-3-(furan-2-yl) acrylamide by marine and terrestrial fungi and absolute configuration of (R)-2-cyano-3-(furan-2-yl) propanamide determined by calculations of electronic circular dichroism (ECD) spectra

This work reports the green organic chemistry synthesis of E-2-cyano-3(furan-2-yl) acrylamide under microwave radiation (55 W), as well as the use of filamentous marine and terrestrial-derived fungi, in the first ene-reduction of 2-cyano-3-(furan-2-yl) acrylamide to (R)-2-cyano-3-(furan-2-yl)propanamide. The fungal strains screened included Penicillium citrinum CBMAI 1186, Trichoderma sp. CBMAI 932 and Aspergillus sydowii CBMAI 935, and the filamentous terrestrial fungi Aspergillus sp. FPZSP 146 and Aspergillus sp. FPZSP 152. A compound with an uncommon CN-bearing stereogenic center at the α-C position was obtained by enantioselective reactions mediated in the presence of the microorganisms yielding the (R)-2-cyano-3-(furan-2-yl) propanamide 3a. Its isolated yield and e.e. ranged from 86% to 98% and 39% to 99%, respectively. The absolute configuration of the biotransformation products was determined by time-dependent density functional theory (TD-DFT) calculations of electronic circular dichroism (ECD) spectra. Finally, the tautomerization of 2-cyano-3-(furan-2-yl) propanamide 3a to form an achiral ketenimine was observed and investigated in presence of protic solvents.

Enantio-, Regio-, and Chemoselective Lipase-Catalyzed Polymer Synthesis

In contrast to chemical routes, enzymatic polymerization possesses favorable characteristics of mild reaction conditions, few by-products, and high activity toward cyclic lactones which make it a promising technique for constructing polymeric materials. Meanwhile, it can avoid the trace residue of metallic catalysts and potential toxicity, and thus exhibits great potential in the biomedical fields. More importantly, lipase-catalyzed polymer synthesis usually shows favorable enantio-, regio-, and chemoselectivity. Here, the history and recent developments in lipase-catalyzed selective polymerization for constructing polymers with unique structures and properties are highlighted. In particular, the synthesis of polymeric materials which are difficult to prepare in a chemical route and the construction of polymers through the combination of selective enzymatic and chemical methods are focused. In addition, the future direction is proposed especially based on the rapid developments in computational chemistry and protein engineering techniques.

Two Enzyme Cooperatively Catalyzed Tandem Polymerization for the Synthesis of Polyester Containing Chiral (R)- or (S)-Ibuprofen Pendants

An interesting cooperation between Candida antarctica Lipase B (CAL-B) and alkaline protease from Bacillus subtilis (BSP) in the copolymerization of bulky ibuprofen-containing hydroxyacid methyl ester (HAEP) and ε-caprolactone (ε-CL) is observed. This cooperation improved the M¯n of the polymers from 3130 (CAL-B) to 9200 g mol-1 (CAL-B/BSP). Experimental results clearly indicate that CAL-B mainly catalyzes the ring-opening polymerization (ROP) of ε-CL under the initiation of HAEP to form the homopolymer of ε-CL, while BSP catalyzes the subsequent polycondensation of the ROP product to yield the copolymer with increased molecular weight. Furthermore, using suitable chemo-enzymatic methods, valuable polyesters with chiral (R)- or (S)-ibuprofen pendants can be tailor-made.

Chemoenzymatic synthesis of polymeric materials using lipases as catalysts: a review

In the past two decades, enzymatic polymerization has rapidly developed and become an important polymer synthesis technique. However, the range of polymers resulting from enzymatic polymerization could be further expanded through combination with chemical methods. This review systematically introduces recent developments in the combination of lipase-catalyzed polymerization with atom transfer radical polymerization (ATRP), kinetic resolution, reversible addition-fragmentation chain transfer (RAFT), click reaction and carbene chemistry to construct polymeric materials like block, brush, comb and graft copolymers, hyperbranched and chiral polymers. Moreover, it presents a thorough and descriptive evaluation of future trends and perspectives concerning chemoenzymatic polymerization. It is expected that combining enzymatic polymerization with multiple chemical methods will be an efficient tool for producing more highly advanced polymeric materials.

New generation of biocatalysts for organic synthesis

The use of enzymes as catalysts for the preparation of novel compounds has received steadily increasing attention over the past few years. High demands are placed on the identification of new biocatalysts for organic synthesis. The catalysis of more ambitious reactions reflects the high expectations of this field of research. Enzymes play an increasingly important role as biocatalysts in the synthesis of key intermediates for the pharmaceutical and chemical industry, and new enzymatic technologies and processes have been established. Enzymes are an important part of the spectrum of catalysts available for synthetic chemistry. The advantages and applications of the most recent and attractive biocatalysts--reductases, transaminases, ammonia lyases, epoxide hydrolases, and dehalogenases--will be discussed herein and exemplified by the syntheses of interesting compounds.