Practical, convergent total synthesis of polyamine amide spider toxin NSTX-3
作者:Ian S Blagbrough、Eduardo Moya、Steven P Walford
DOI:10.1016/0040-4039(95)02238-4
日期:1996.1
A practical, totalsynthesis of polyamine amide spider toxin NSTX-3, a potent glutamate receptor antagonist with potential as a neuroprotective agent, is reported. The unsymmetrical polyamine motiety was built by a conjugate addition to afford putreamine and regioselective acylation of L-asparaginyl-cadaverine.
Screwed in place: An anti‐parallel double‐helical aromatic oligoamide foldamer was shown to bind to a series of rodlikeguests of various lengths upon the winding of the duplex around the guests (see scheme). Solid‐state crystal structures of the host–guest complexes show that the two strands of the duplex undergo a relative screw motion to adjust the distance between hydrogen‐bond donors located at
Novel pseudo[2]rotaxanes constructed by the self-assembly of dibenzyl tetramethylene bis-carbamate derivatives and per-ethylated pillar[5]arene
作者:Shuhan Xiong、Xiaoning Zhang、Lu-Bo Meng、Juli Jiang、Chen Lin、Leyong Wang
DOI:10.1039/c5cc01345c
日期:——
Novel neutral guest molecules, G1-G7, are studied for their host-guest complexation with per-ethylatedpillar[5]arene (EtP[5]A). Among them, G1 and G7 , dibenzyl tetramethylene bis-carbamate derivatives, are found to afford a novel stable pseudo[2]rotaxane with EtP[5]A, respectively, and G7 subset EtP[5]A shows photoresponsive properties.
A total synthesis of polyamines was developed using potassium phthalimide as a sole nitrogen source. 15N-Enriched phthalimide was prepared almost quantitatively from 15N-enriched ammonium sulfate by a modified method. Key compounds for the synthesis of 15N-enriched spermidine and spermine were 15N-enriched putrescine (I), N-(3-bromopropyl)-phthalimide (II), N-(4-bromobutyl) phthalimide (III), and benzylamine, which were easily prepared in high yields from potassium 15N-enriched phthalimide. Spermidine was synthesized by two alternative methods involving an alkylation of monobenzyloxycarbonyl putrescine with II and a stepwise alkylation of benzylamine with II and III in the presence of KF-Celite. The lattter method allowed the preparation of all seven kinds of various 15N-enriched spermidines with combinations of the three reagents containing 15N or 14N. Spermine was similarly synthesized by an alkylation of N, N'-dibenzylputrescine with II. In these methods, the alkylation using KF-Celite was extremely useful for the synthesis of spermidine and spermine. The present methods were also used to synthesize various other polyamines in high yields.
使用邻苯二甲酰亚胺钾作为唯一氮源开发了多胺的全合成。通过改进的方法,由富 15N 硫酸铵几乎定量地制备了 15N 富集邻苯二甲酰亚胺。合成 15N 富集亚精胺和精胺的关键化合物是 15N 富集腐胺 (I)、N-(3-溴丙基)-邻苯二甲酰亚胺 (II)、N-(4-溴丁基) 邻苯二甲酰亚胺 (III) 和苯甲胺,其中可以很容易地从富含 15N 的邻苯二甲酰亚胺钾中以高产率制备。亚精胺通过两种替代方法合成,包括在 KF-硅藻土存在下用 II 对单苄氧基羰基腐胺进行烷基化,以及用 II 和 III 对苄胺进行逐步烷基化。后一种方法允许通过含有15N或14N的三种试剂的组合来制备所有七种不同的富含15N的亚精胺。类似地,通过用II烷基化N,N'-二苄基腐胺来合成精胺。在这些方法中,使用 KF-Celite 进行烷基化对于亚精胺和精胺的合成非常有用。本方法还用于高产率合成各种其他多胺。
Nontraditional Fragment Couplings of Alcohols and Carboxylic Acids: C(<i>sp</i><sup>3</sup>)–C(<i>sp</i><sup>3</sup>) Cross-Coupling via Radical Sorting
作者:Holt A. Sakai、David W. C. MacMillan
DOI:10.1021/jacs.2c02062
日期:2022.4.13
describe the C(sp3)–C(sp3) cross-coupling of alcohols and carboxylicacidsthrough the dual combination of N-heterocyclic carbene (NHC)-mediated deoxygenation and hypervalent iodine-mediated decarboxylation. This mild and practical Ni-catalyzed radical-coupling protocol was employed to prepare a wide array of alkyl–alkyl cross-coupled products, including highly congested quaternary carbon centers from