Synthesis Of Stable Isotope Labeled β-Agonists Cimaterol-D₆ And Clenproperol-D₆

With the rapid growth of food products in China, the problems of food safety were becoming more and more serious. Especially, the incedent of "lean meat powder" has received immense attention. "Lean meat powder" is a beta-agonist, the illegal use in livestock production has led to toxic effects after human consumption of meat products, such as cardiac palpitation,vomit, fever and nervousness. β-agonist is harmful to human health because it is teratogenic and mutagenic. At present, the most authoritative method for the detection of β-agonist residues is isotope dilution mass spectrometry, which can improve the accuracy of detection. Stable isotope internal standard reagent is the key to this method.Isopropylamine-D6 was synthesized as a key intermediate, two isotopic internal standard reagents: cimatro-D6 and clenbuterol-D6 were synthesized according to the standard of internal reagent. The reaction conditions were investigated and optimized by using natural abundance of raw materials. After the improvement of each step of experimental explorations, the total synthesis was conducted, and the abundance experiments were carried out.(1) Acetone-D6 was converted to 2-bromopropane-D6 by reduction and bromination. Then isopropylamine-D6 was prepared according to the Gabriel synthesis method. The synthesis of N-isopropylphthalimide-D6 was optimized in order to improve the utilization of isotope atom.The optimum conditions: the molar ratio n (bromoisopropane-D6): n (phthalimide potassium)＝1 : 1.2, reaction time 4 h, with 110 ℃ to obtain N-isopropylphthalimide-D6 with yield of 94.5 %. The chemical purity of up to 98.5%, isotopic abundance is 99.7 % atomD.(2) 4-Aminoacetophenone was converted to 2-amino-5-(2-bromoacetyl)benzonitrile by a series of reactions, then 2-amino-5-(2-bromoacetyl)benzonitrile was bromided, aminated and reductived to synthesize cimatro-D6 with isopropylamine-D6 as labeling precursor. The optimal reaction conditions: the molar ratio n (isopropylamine-D6) : n (2-amino-5-(2-bromoacetyl)benzonitrile) = 1:1,at 35 ℃ for 6 hours. The yield of cimatro-D6 was 35.3 %(base on isopropylamine-D6), the isotopic abundance was 99.1 % atom D.(3) 3,5-dichloro-Aminoacetophenone was bromided, aminated and reductived to synthesize clenbuterol-D6 with isopropylamine-D6 as labeling precursor. The optimal reaction conditions: the molar ratio n (3,5-dichloro-Aminoacetophenone): n (isopropylamine-D6) = 2 :1, at 65 ℃ for 5.5 hours. The yield of clenbuterol-D6 was 28.0 % (base on isopropylamine-D6), the isotopic abundance was 99.5 % atom D.