2-Methoxyethoxymethyl (MEM) and 2-(trimethylsilyl)ethoxymethyl (SEM) groups were used to protect the sn-3-OH of optically active glycerols in the synthesis of 1,2-di-O-octadecyl-sn-glycero-3-phosphatidylcholine. Both MEM and SEM protective groups had advantages of a classical benzyl group by virtue of (i) the facile preparation of 1,2-O-isopropylidene-3-O-(2-methoxyethoxymethyl)-sn-glycerol and its sn-3-O-SEM analog as starting materials and (ii) the rapid demasking of the MEM and SEM moieties in lipid precursors, especially by means of titanium tetrachloride.
在合成1,2-二-O-
十八烷基-sn-
甘油-3-
磷脂酰
胆碱的过程中,使用了2-甲氧基乙氧基甲基(M
EM)和2-(三甲基
硅基)乙氧基甲基(
SEM)保护基团来保护光学活性
甘油的sn-3-OH。这两种保护基团具有经典苄基的优点,具体体现在:(i) 1,2-O-异
丙烯基-3-O-(2-甲氧基乙氧基甲基)-sn-
甘油及其sn-3-O-
SEM类似物作为起始材料的制备方便;(ii) 在脂质前体中,特别是通过
四氯化钛,M
EM和
SEM基团的快速去掩蔽。