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Unnatural amino acids attract growing attention for pharmaceutical applications as they are useful building blocks for the synthesis of a number of chiral drugs. Here, we describe a two‐step enzymatic method for the asymmetric synthesis of homoalanine from L‐methionine, a cheap and readily available natural amino acid. First, the enzyme L‐methionine γ‐lyase (METase), from Fusobacterium nucleatum, catalyzed the γ‐elimination of L‐methionine to 2‐oxobutyrate. Second, an amino acid aminotransferase catalyzed the asymmetric conversion of 2‐oxobutyrate to either L‐ or D‐homoalanine. The L‐branched chain amino acid aminotransferase from Escherichia coli (eBCAT), using L‐glutamate as amino donor, produced L‐homoalanine (32.5 % conv., 28 % y, 99 % ee) and the D‐amino acid aminotransferase from Bacillus sp. (DATA) used D‐alanine as amino donor to produce D‐homoalanine (87.5 % conv., 69 % y, 90 % ee). Thus, this concept allows for the first time the synthesis of both enantiomers of this important unnatural amino acid.

a b s t r a c tThe present Letter details our findings on the lipase-catalyzed Michael reactions between primary or secondary amines and acrylonitrile. Several lipases were evaluated, and good results were obtained leading to the formation of Michael adducts in shorter reaction times than the uncatalyzed reactions.

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A reação de esterificação catalisada por lípases foi investigada através da utilização de irradiação de microondas e aquecimento convencional com a finalidade de avaliar a presença de efeitos não térmicos de microondas na síntese de biodisel. Todas as reações foram conduzidas em equipamentos dedicados a síntese orgânica como Monowave 300 e CEM Discover, a 40 °C e com controle interno da temperatura reacional através do uso de sondas de fibra ótica. Os experimentos sob aquecimento convencional foram realizados em reator automatizado EasyMax™ (MettlerToledo) que também permite o controle da temperatura interna do meio reacional. Os resultados obtidos mostram que não há diferença entre a reação conduzida sob irradiação de microondas e aquecimento convencional, diferentemente do apontado em alguns relatos da literatura.The esterification reaction mediated by lipases was investigated applying both microwave irradiation and conventional heating in order to evaluate the existence of nonthermal microwave effects on the biodiesel synthesis. All transformations were conducted at 40 °C in both Monowave 300 and CEM Discover instruments that allowed accurate internal reaction temperature measurements with use of fiber-optic probes. The conventional heating experiment was performed in an EasyMax™ reactor (Mettler-Toledo), which also allowed accurate measurement of the internal temperature. The results revealed no difference on the reaction time or yield, differently than indicated by some results in the literature.