Enantiospecific synthesis of (-)-tabtoxinine .beta.-lactam
摘要:
A convergent, 10-step synthesis of optically active tabtoxinine beta-lactam [(-)-1] has been described. Key features of the synthetic route include (1) preparation of a new gamma-cation amino acid synthon, (-)-4, and its use as an electrophile (3 --> 11); (2) the one-pot conversion of methyl sulfide 11 to the Cbz-protected amine 12 via stereoselective sulfilimine rearrangement; and (3) chemoselective lactone ring opening in spiro lactam 15a. Synthons (-)-4 and 3 are available on a semipreparative scale.
Enantiospecific synthesis of (-)-tabtoxinine .beta.-lactam
摘要:
A convergent, 10-step synthesis of optically active tabtoxinine beta-lactam [(-)-1] has been described. Key features of the synthetic route include (1) preparation of a new gamma-cation amino acid synthon, (-)-4, and its use as an electrophile (3 --> 11); (2) the one-pot conversion of methyl sulfide 11 to the Cbz-protected amine 12 via stereoselective sulfilimine rearrangement; and (3) chemoselective lactone ring opening in spiro lactam 15a. Synthons (-)-4 and 3 are available on a semipreparative scale.
Synthetic studies on tabtoxin. Synthesis of a naturally occuring inhibitor of glutamine synthetase, tabtoxinine-β-lactam, and analogues
作者:Jack E. Baldwin、Masami Otsuka、Philip M. Wallace
DOI:10.1016/s0040-4020(01)87377-4
日期:1986.1
(±)- Tabtoxinine-β-lactam 2, a potent inhibitor of glutaminesynthetase, and related compounds, have been synthesised by a cycloaddition approach. The cycloaddition of an acylnitroso compound to cyolohexadienes proceeded regioselectively to give the bicyclic, ester 8 (X=CO2Et) or nitrile 24. These were converted into the cyclic diacids 15, 17, 27 and 33 by permanganate oxidation. A benzyl chloroformate
已经通过环加成法合成了谷氨酰胺合成酶的有效抑制剂(±)-毒素-β-内酰胺2和相关化合物。酰基亚硝基化合物与环己二烯的环加成反应选择性进行,得到双环酯8(X = CO 2Et)或腈24。通过高锰酸盐氧化将其转化为环状二酸15、17、27和33。开发了氯甲酸苄酯介导的酯化方法,以区分两个羧基以提供单酯16a,19、28a和34。用氯甲酸苄酯处理羟基二酸20得到了螺旋β-内酯11。β-氨基酸的环化29和35之后氢化,分别得到(±)-塔宾毒素-β-内酰胺2和甲氧基衍生物5。备选地,通过将硝酮39区域选择性地进行1,3-偶极环加成,将螺环β-内酰胺45a和45b以41:59的比例获得到外亚甲基β-内酰胺44上。
Stereoselective Synthesis of Tabtoxinine-β-lactam by Using the Vinylogous Mukaiyama Aldol Reaction with Acetate-Type Vinylketene Silyl <i>N</i>,<i>O</i>-Acetal and α-Keto-β-lactam
Stereoselective total synthesis of tabtoxinine-β-lactam has been achieved. The vinylogous Mukaiyama aldol reaction with vinylketene silyl N,O-acetal and α-keto-β-lactam proceeded to afford the adduct possessing a TβL-skeleton with a tert-alcohol in high yield and stereoselectivity. Stereoselective introduction of the amino group has been accomplished by azidation at the α position of the imide followed
Synthesis of (-)-tabtoxinine-β-lactam and its (3R)-isomer, the cause of tobacco wildfire disease, was achieved from l-serine using a zinc-mediated coupling reaction, Sharpless asymmetric dihydroxylation and lactamization of β-mesyloxy benzylhydroxamate amide as the key steps.