盐酸L-肉碱和盐酸乙酰L-肉碱的合成

L-肉碱(维生素BT)和乙酰L-肉碱是长链脂肪酸运输的载体, 广泛用于医药、保健食品及饲料等行业. 本工作介绍了一种化学不对称合成盐酸L-肉碱和盐酸乙酰L-肉碱的方法. 以自制的手性噁唑硼烷为催化剂, 将起始原料γ-氯乙酰乙酸乙酯不对称催化氢化还原成(R)-γ-氯-β-羟基丁酸乙酯, 这一步的化学收率和光学收率都较高. 然后将(R)-γ-氯-β-羟基丁酸乙酯转化为盐酸L-肉碱和盐酸乙酰L-肉碱. 合成盐酸L-肉碱只需两步, 总收率为68.3%, ee值可达94.6%; 合成盐酸乙酰L-肉碱需三步, 总收率为62.6%, ee值可达96.8%. 还考察了反应温度、催化剂及还原剂的量等因素对γ-氯乙酰乙酸乙酯的不对称氢化还原的化学产率和光学收率的影响.

Enantioselective Synthesis of L-Carnitine and Ace-tyl-L-carnitine Hydrochlorides

A new pulse sequence is proposed for extracting subspectra of individual components of sugar chains. The method uses a combination of the MMDY composite pulse and the double pulsed field gradient spin-echo and is shown to be useful in the analysis of complex spectra with many overlapped signals. The main advantages of this method are: (i) a significant decrease in experiment acquisition times; (ii) the mag- netization transfer is especially efficient, for example, for sugar residues such as Ara and Rha, which have one of the coupling of ca. 1 Hz around the sugar rings, complete subspectra can be quickly obtained; (iii) high-quality pure-absorption phase subspectra can be recorded without the use of the Z-filter technique; (iv) since the gradients merely serve to suppress unwanted signals, they are not subject to the sensitivity losses associated with gradient coherence pathway selection. Its application to the separation of severely overlap- ping spin systems is illustrated using glycoside sample.