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以甘氨酸(Ⅰ)为原料,在羧基保护下合成底物苯亚甲氨基乙酸乙酯(Ⅲ),然后经手性催化剂(一)-N-苄基氯化辛可尼定(BCDC)和(+)-N-苄基氯化辛可宁(BCNC)的催化,酸水解得到旋光性的2,4,6-三甲基苯丙氨酸(V-2,V-3),总收率分别为28%和31%,比旋光度分别为[a]_D~(20)=+16°和[α]_D~(20)=—9°。以氯化三乙基苄胺(TEBA)作非手性相转移催化剂得到了消旋2,4,6-三甲基苯丙氨酸(V-1),总收率为32%。并探讨了利用手性相转移催化剂不对称合成的反应机理。
Glycine (Ⅰ) was used as the starting material to synthesize the ethyl benzylideneaminoacetate (Ⅲ) under the protection of carboxyl group. Then the chiral catalysts (Ⅰ), N-benzylcyclidine (BCDC) ) -N-benzylcarnitine (BCNC) catalyzed acid hydrolysis to give optically active 2,4,6-trimethylphenylalanine (V-2, V-3) % And 31%, respectively. The specific rotation is [a] _D ~ (20) = + 16 ° and [α] _D ~ (20) = -9 °, respectively. Racemic 2,4,6-trimethylphenylalanine (V-1) was obtained using an achiral phase transfer catalyst with triethylbenzylamine chloride (TEBA) in a total yield of 32%. The reaction mechanism of asymmetric synthesis using chiral phase transfer catalyst was also discussed.