The present invention relates to a new process for the generation of pyrazines consisting in the bioconversion of hydroxyketones with 1,2-diaminopropane. New tetrahydropyrazine derivatives as well as new dihydropyrazine derivatives with high flavour and low threshold properties are disclosed. Such pyrazines compounds exhibiting roasted and earthy aroma profiles may be used in the food and bevererage industry, especially chocolate, confectionery and coffee.
Use Of The PIGD Protein For Catalyzing 1,4-Additions Of 2-Oxoalkanoates To Alpha, Beta-Unsaturated Ketones
申请人:Müller Michael
公开号:US20100305337A1
公开(公告)日:2010-12-02
The present invention relates to the preparation of compounds of the general formula II
which can be obtained by 1,4 addition of 2-oxoalkanoates or 2-oxocarboxylic acids onto the appropriate ketones. The present invention also relates to the use of the PigD protein for catalysis of 1,4 additions of 2-oxoalkanoates/-carboxylic acids, for example pyruvate/pyruvic acid or 2-oxobutyrate/2-oxobutyric acid, onto aliphatic, aromatic and heterocyclic α,β-unsaturated ketones. The 1,4 additions are effected here with CO
2
elimination. The use of the PigD protein as a catalyst in the aforementioned 1,4 additions enables the synthesis of addition products with stereoactive centers these addition products being preparable with an enantiomeric excess of more than 80% ee. The aliphatic, aromatic and heterocyclic α,β-unsaturated ketones which are suitable for the process are represented by the general formula I:
Twenty-five acyloins were generated by biotransformation of aliphatic aldehydes and 2-ketocarboxylic acids using whole cells of baker's yeast as catalyst. Six of these acyloins were synthesized and tentatively characterized for the first time. Subsequent chemical reaction with 1,2-propanediamine under mild conditions resulted in the formation of thirteen 5,6-dihydropyrazines and six tetrahydropyrazines
以面包酵母的整个细胞为催化剂,通过脂肪族醛和2-酮羧酸的生物转化,产生了二十五个酰化甘油。首次合成了其中的六种酰基辅酶,并对其进行了初步鉴定。随后在温和的条件下与1,2-丙二胺发生化学反应,导致形成了十三种5,6-二氢吡嗪和六种四氢吡嗪。对它们的气味质量进行了评估,并估计了它们的气味阈值。在这些吡嗪衍生物中,2-乙基-3,5-二甲基-5,6-二氢吡嗪(烤,坚果,0.002 ng / L空气),2,3-二乙基-5-甲基-5,6-二氢吡嗪(烤,空气中的浓度为0.004 ng / L)和2-乙基-3,5-二甲基四氢吡嗪(面包类面包皮,空气中的浓度为1.9 ng / L)是气味最强烈的活性化合物。
VERWENDUNG DES PIGD-PROTEINS ZUR KATALYSE VON 1,4-ADDITIONEN VON 2-OXOALKANOATEN AN ALPHA, BETA-UNGESÄTTIGTE KETONE