A concise synthesis of enantiomerically pure L(4-boronophenyl)alanine from L-tyrosine
A concise synthesis of enantiomerically pure L(4-boronophenyl)alanine from L-tyrosine
复制标题
DOI：
10.1021/jo980818r
复制
发表时间：
1998-10-16
影响因子：
3.6
通讯作者：
Yamamoto, Y
中科院分区：
文献类型：
--
作者：
Nakamura, H;Fujiwara, M;Yamamoto, Y
4-Boronophenylalanine (BPA)1 is a practical boron compound, which is clinically used not only for the treatment of malignant melanoma but also for that of brain tumor, on neutron capture therapy (NCT).1–3 Since Mishima and co-workers4 revealed that theL-form of BPA is more efficiently incorporated into melanoma cells than racemic one, the enantioselective synthesis ofL-BPA has been required. EnrichedL-BPA was prepared enzymatically through α-chymotrypsin hydrolysis5 of the ethyl ester of racemic BPA synthesized by the traditional method.1,6 In this case, 50% of another enantiomer (D-BPA) was recovered from the racemic material. Recently, two synthetic routes ofL-BPA were reported. Asymmetric hydrogenation route gaveL-BPA with enantiomeric excess of up to 88% (96% ee after recrystallization).7 Another route using palladium-catalyzed coupling reaction of iodophenylboronate with the chiral organozinc derived fromL-serine needed rather lengthy synthetic steps.8 Herein we report a concise synthesis of enantiomerically pureL-BPA fromL-tyrosine using palladium-catalyzed carbon-boron bond formation reaction (eq. 1).
