617-73-2Relevant articles and documents
Synthesis and properties of novel poly(hexyl-substituted lactides) for pharmaceutical applications
Trimaille, Thomas,Gurny, Robert,Moeller, Michael
, p. 348 - 352 (2005)
Monohexyl-substituted lactide (mHLA) was synthesized by reaction of 2-hydroxyoctanoic acid with 2-bromopropionyl bromide, and polymerized with tin(II) 2-ethylhexanoate (Sn(Oct)2) or 4-dimethylaminopyridine (DMAP) in the presence of benzyl alcohol by ring-opening polymerization (ROP). Poly(monohexyl-substituted lactide) (Pm-HLA) of predictable molecular weights and narrow polydispersities were obtained in convenient bulk conditions at 100°C within short polymerization times. The polymerizations were well controlled, showing a 'living' character for targeted degrees of polymerization up to DP = 60 as evidenced by molecular weight versus conversion studies and 1H NMR end group analysis. The hexyl groups have a strong impact on the glass transition temperature (Tg), which is low for PmHLA compared to standard poly(D,L-lactide) (PLA). Tg and zero shear viscosities at 25°C can be controlled by the polymer molecular weight, ranging from -22°C for Mn = 2800 g/mol to -10°C for M n = 9100 g/mol and 140 to 4850 Pa.s, respectively. These data are in correspondence with the Fox and Flory equations. The degradation mechanism of the PmHLA polymer in phosphate buffer pH 7.4 at 37°C was shown to be similar to that of the standard PLA ('bulk erosion' type), with a slightly higher degradation rate, leading to the non-toxic degradation products lactic acid and 2-hydroxyoctanoic acid. PmHLA has the great potential as an alternative to conventional PLA/PLGA for drug delivery systems. By the hexyl-substitution the biodegradable PLA-ester backbone is conserved but the hydrophobicity is increased in comparison to standard PLA, while a viscous polymer is obtained. This leads to advantageous injectable solvent-free drug delivery systems, in which drugs can easily be incorporated by simple mixing. Schweizerische Chemische Gesellschaft.
P450Jα: A New, Robust and α-Selective Fatty Acid Hydroxylase Displaying Unexpected 1-Alkene Formation
Armbruster, Julia,Steinmassl, Mathilde,Müller Bogotá, Christina A.,Berg, Gabriele,Nidetzky, Bernd,Dennig, Alexander
, p. 15910 - 15921 (2020/10/29)
Oxyfunctionalization of fatty acids (FAs) is a key step in the design of novel synthetic pathways for biobased/biodegradable polymers, surfactants and fuels. Here, we show the isolation and characterization of a robust FA α-hydroxylase (P450Jα) which catalyses the selective conversion of a broad range of FAs (C6:0-C16:0) and oleic acid (C18:1) with H2O2 as oxidant. Under optimized reaction conditions P450Jα yields α-hydroxy acids all with >95 % regioselectivity, high specific activity (up to 15.2 U mg?1) and efficient coupling of oxidant to product (up to 85 %). Lauric acid (C12:0) turned out to be an excellent substrate with respect to productivity (TON=394 min?1). On preparative scale, conversion of C12:0 reached 83 % (0.9 g L?1) when supplementing H2O2 in fed-batch mode. Under similar conditions P450Jα allowed further the first biocatalytic α-hydroxylation of oleic acid (88 % conversion on 100 mL scale) at high selectivity and in good yields (1.1 g L?1; 79 % isolated yield). Unexpectedly, P450Jα displayed also 1-alkene formation from shorter chain FAs (≤C10:0) showing that oxidative decarboxylation is more widely distributed across this enzyme family than reported previously.
Preparative Asymmetric Synthesis of Canonical and Non-canonical a-amino Acids through Formal Enantioselective Biocatalytic Amination of Carboxylic Acids
Dennig, Alexander,Blaschke, Fabio,Gandomkar, Somayyeh,Tassano, Erika,Nidetzky, Bernd
supporting information, p. 1348 - 1358 (2019/10/28)
Chemical and biocatalytic synthesis of non-canonical a-amino acids (ncAAs) from renewable feedstocks and using mild reaction conditions has not efficiently been solved. Here, we show the development of a three-step, scalable and modular one-pot biocascade for linear conversion of renewable fatty acids (FAs) into enantiopure l-a-amino acids. In module 1, selective a-hydroxylation of FAs is catalyzed by the P450 peroxygenase P450CLA. By using an automated H2O2 supplementation system, efficient conversion (46 to >99%; TTN>3300) of a broad range of FAs (C6:0 to C16:0) into valuable a-hydroxy acids (a-HAs; >90% a-selective) is shown on preparative scale (up to 2.3 gL1 isolated product). In module 2, a redox-neutral hydrogen borrowing cascade (alcohol dehydrogenase/amino acid dehydrogenase) allowed further conversion of a-HAs into l-a-AAs (20 to 99%). Enantiopure l-a-AAs (e.e. >99%) including the pharma synthon l-homo-phenylalanine can be obtained at product titers of up to 2.5 gL1. Based on renewables and excellent atom economy, this biocascade is among the shortest and greenest synthetic routes to structurally diverse and industrially relevant ncAAs.
