Stereoselective synthesis of MeBmt and methyl (4R,5S)-5-isopropyl-2- phenyloxazoline-4-carboxylate by a Pd-catalyzed equilibration.
Stereoselective synthesis of MeBmt and methyl (4R,5S)-5-isopropyl-2- phenyloxazoline-4-carboxylate by a Pd-catalyzed equilibration.
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DOI：
10.1021/jo015760m
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发表时间：
2001-10
期刊：
影响因子：
--
通讯作者：
G. Cook;P. Shanker
中科院分区：
文献类型：
--
作者：
G. Cook;P. Shanker
Lactacystin(1)于1991年分离，因其对20个S蛋白酶体的高效选择性抑制作用而成为近年来研究的热点。2，3 1992年Corey小组首次报道了1的全合成，随后描述了合成的进展和同样有效的内酯类似物2的制备。4利用手性来源如D-葡萄糖、5-D-谷氨酸、6和由不对称的不对称环氧化衍生的烯丙醇，已经出现了多种其他合成方法。7合成了3-羟基亮氨酸衍生物恶唑啉3，并用其作为关键中间体合成了lactacystin。大村和Smith8以(E)-4-甲基-3-戊烯-1-醇为原料，也是通过夏普莱斯环氧化，经10步反应制得3，总收率41%。另一条路线是4-甲基-2-戊烯酸甲酯与70%ee的不对称双羟基化反应，通过一次重结晶可以提高到~gt；99%ee。9 Panek基团最近利用不对称氨羟基化反应，从对溴苯基(E)-4-甲基-2-戊烯酸酯传递了一条更直接的路线。10的区域选择性为7：1，对R-氨基酯有利，ee为87%。最近，O-苄基羟胺(80%De)的手性辅助定向共轭加成，然后是氮杂环丙烷的形成和开环，得到了类似的羟基亮氨酸衍生物。11 MeBmt(4)是另一种罕见的R-氨基-羟基酸，是环孢素的重要成分之一。12由L-(+)-酒石酸二乙酯首次合成MeBmt是Wenger于1983年报道的。13从那时起，出现了许多基于不对称羟醛缩合反应的合成方法，14手性环氧化物的开环，15或从天然手性构建块(D-异抗坏血酸，16 L-谷氨酸，17 D-2-脱氧核糖，18 D-葡萄糖，19和D-丝氨酸20)开始。最近，报道了2-恶唑酮杂环上的立体选择性自由基加成反应。21(1)(A)大村，S.；藤本，T.；Otoguro，K.；松崎，K.；森口，R.；田中，H.；佐崎，Y.J.Antibiot。(B)大村，S.；松崎，K.；藤本，T.；Kosuge，K.；古屋，T.；藤田，S.；
Lactacystin (1), isolated in 1991, 1 has been a target of intense study recently due to its highly potent and selective inhibition of the 20 S proteasome. 2, 3 The first total synthesis of 1 was reported by the Corey group in 1992, and subsequent evolution of the synthesis and the preparation of the equally potent lactone analogue 2 have been described. 4 A variety of other synthetic approaches have appeared utilizing chiral sources such as D-glucose, 5 D-glutamic acid, 6 and an allylic alcohol derived from a Sharpless asymmetric epoxidation. 7 The 3-hydroxyleucine derivative, oxazoline 3, has been employed as a key intermediate in the total synthesis of lactacystin. Omura and Smith8 prepared 3 from (E)-4-methyl-3-penten-1-ol, also via Sharpless epoxidation, in 10 steps with 41% overall yield. Another route utilized a Sharpless asymmetric dihydroxylation of methyl 4-methyl-2-pentenoate with 70% ee, which could be improved to> 99% ee by one recrystallization. 9 The Panek group has recently communicated a more direct route from p-bromophenyl (E)-4-methyl-2-pentenoate utilizing an asymmetric aminohydroxylation reaction. 10 Regioselectivity was 7: 1 favoring the R-amino ester with 87% ee. And more recently, a chiral auxiliary-directed conjugate addition of O-benzylhydroxylamine (80% de), followed by aziridine formation, and ring opening, afforded a similar hydroxyleucine derivative. 11 MeBmt (4), another unusual R-amino--hydroxy acid, is an important constituent of cyclosporin. 12 The first synthesis of MeBmt from L-(+)-diethyl tartrate was reported by Wenger in 1983. 13 Since then, a number of synthetic approaches have appeared relying on asymmetric aldol reactions, 14 opening of chiral epoxides, 15 or beginning with natural chiral building blocks (D-isoascorbic acid, 16 L-glutamic acid, 17 D-2-deoxyribose, 18 D-glucose, 19 and D-serine20). Most recently, a stereoselective radical addition to a 2-oxazolone heterocycle was reported. 21 (1)(a) Omura, S.; Fujimoto, T.; Otoguro, K.; Matsuzaki, K.; Moriguchi, R.; Tanaka, H.; Sasaki, Y. J. Antibiot. 1991, 44, 113.(b) Omura, S.; Matsuzaki, K.; Fujimoto, T.; Kosuge, K.; Furuya, T.; Fujita, S.;