α-氨基酰胺类化合物的立体选择性合成新方法

以(R)-1-苯乙胺为起始原料,合成了手性氨甲酰基硅烷4。通过4与无手性的亚胺5a、5b和5c以及有手性的亚胺7a、7b和7c反应,得到了立体选择性加成产物α-氨基酰胺衍生物6b、6c、8a、8b和8c,其中6c、8a和8c是高立体选择性产物。手性氨甲酰基硅烷与亚胺的反应具有立体选择性,其立体选择性大小与在亚胺双键氮原子和碳原子上所连的取代基有关,因此通过选择不同的取代基可有效地不对称合成α-氨基酰胺衍生物。     

新型6-(4-氨基苯基)-4,5-二氢-3(2H)-哒嗪酮α-氨基膦酸酯衍生物的合成

以乙酰苯胺与丁二酸酐为原料,经Friedel-Crafts酰化反应、水解脱乙酰基和水合肼缩合制得中间体6-(4-氨基苯基)-4,5-二氢-3(2H)-哒嗪酮(3);3与芳醛和亚磷酸二乙酯经类Mannich-type反应合成了5个新型的6-(4-氨基苯基)-4,5-二氢-3(2H)-哒嗪酮α-氨基膦酸酯衍生物,其结构经1H NMR,~(13)C NMR,31P NMR,IR和ESI-MS表征。     

代谢标记小分子探针6-炔基-2-乙酰氨基半乳糖的合成

以乙酰氨基半乳糖为起始原料,经过叔丁基二甲基硅基对糖环的6位选择性保护,随后将1,3,4进行甲氧甲基保护,选择性脱除6位保护基,经Dess-Martin氧化、Bestmann′s试剂和酸性条件下去保护后得到目标化合物,并通过单晶衍射确定了中间体7的结构;本文为6-炔基-2-乙酰氨基半乳糖的合成提供了有效的制备方法,为后续相关生物学研究提供了基础。     

N8-芳基取代4-氨基-6-氯-7(8H)-蝶啶酮的合成

通过N4-芳基取代4,5,6-三氨基嘧啶与草酸二水合物环合, 得到N8-芳基取代4-氨基-5,8二氢-6,7-蝶啶二酮, 再经氯代, 得到新型N8-芳基取代4-氨基-6-氯-7(8H)-蝶啶酮, 用红外光谱、核磁共振氢谱、核磁共振碳谱、质谱和元素分析确证了其结构. 用X-ray单晶衍射测定了4-氨基-6-氯-8-对甲苯基-7(8H)-蝶啶酮(3a)的晶体结构, 证明了环合反应的区域选择性.     

(3S,4S)-4-氨基-3-羟基-6-甲基庚酸的合成

价廉易得的L-亮氨酸先以苄基同时保护氨基及羧基得(S)-2-(二苄胺基)-4-甲基戊酸苄酯,进而在碱性条件下与乙腈发生亲核取代反应得(S)-4-(二苄胺基)-6-甲基-3-氧代庚腈,再经硼氢化钠选择性还原羰基得(3S,4S)-4-(二苄胺基)-3-羟基-6-甲基庚腈,用双氧水氧化得(3S,4S)-4-(二苄胺基)-3-羟基-6-甲基庚酸,最后在Pd(OH)2/C-H2作用下脱掉苄基得到(3S,4S)-4-氨基-3-羟基-6-甲基庚酸,即(3S,4S)-statine。整个合成路线总产率为33.6%。     

4-异丁氧基-10-羟基-1,7-二氮杂菲-2,8-二羧酸甲酯的合成、表征及晶体结构

报道了4-异丁氧基-10-羟基-1,7-二氮杂菲-2,8-二羧酸甲酯(1)的选择性合成.化合物1是以间苯二胺(3)为起始原料,经三步反应合成得来.间苯二胺和1,4-二羧酸二甲酯丁炔(4)反应生成了1,3-二-(1,2-二甲氧羰基-乙烯氨基)苯(5),随后化合物5在二苯醚中加热回流,生成4,10-二羟基-1,7-邻二氮杂菲-2,8-二羧酸甲酯(6)和4,5-二羟基-1,8-二氮杂蒽-2,7-二羧酸甲酯(7).从核磁共振氢谱中可以估算出,化合物6的产率是化合物7的7～9倍.化合物6和7的混合物通过Mitsunobu反应生成了化合物1和4,5-二异丁氧基-1,8-二氮杂蒽-2,7-二羧酸甲酯(2),其中化合物1的产率是化合物2的5～7倍.晶体结构清楚地表明化合物1中10位上的羟基与1位上的氮原子之间形成了六元环分子内氢键,而在化合物2中却没有发现分子内氢键,此现象很好的说明了氢键的形成与选择性合成之间存在着重要的联系.     

3-取代-(1H)-嘧啶[1, 2-a]喹啉-1-酮和2-取代嘧啶[1, 2a]苯骈 咪唑-4-(10H)- 酮的简便合成法

本文利用2-氨基喹啉和2-氨基苯骈咪唑作为亲核试剂,与5-(双甲硫基亚甲基)丙二酸亚异丙酯(1)、5-(甲硫基亚烃基)丙二酸亚异丙酯(3)反应,开发出3-取代-(1H)-嘧啶-[1,2-a]喹啉-1-酮(5)和2-取代嘧啶[1,2-a]苯骈咪唑-4-(10H)-酮(6)通用的简便合成法。     

氨基清除树脂辅助合成2-(7-氟-3-氧-3,4-2H-苯并[b][1,4]噁嗪-6-基)异吲哚1,3-二酮

采用氨基清除树脂辅助合成方法,由6-氨基-7-氟-4-取代基-3(4H)-酮与取代邻苯二甲酸酐在冰醋酸中加热反应制备了2-(7-氟-3-氧-3,4-2H-苯并[b][1,4]噁嗪-6-基)异吲哚-1,3-二酮类化合物,纯度86％～95％．其结构经^1H NMR,IR和MS表征。     

2-芳甲酰氨基硫羰基-3-异噻唑酮及4-氰基-5-甲硫基-2-芳甲酰氨基硫羰基-3-异噻唑酮的合成与生物活性

通过3-羟基异噻唑(4)和4-氰基-5-甲硫基-3-羟基异噻唑(5)分别与芳酰基异硫氰酸酯(3)反应,合成标题化合物2-芳甲酰氨基硫羰基-3-异噻唑酮(6a_6f)和4-氰基-5-甲硫基-2-芳甲酰氨基硫羰基-3-异噻唑酮(7a_7e),对此反应及产物的结构特点进行了探讨.     

6-卤代咪唑并[1,2-a]吡嗪-3-甲酰胺的简便合成

6-卤代咪唑并[1,2-a]吡嗪-3-甲酰胺是一类重要的抗癌新药中间体,广泛应用于淋巴癌、肺癌、皮肤癌等癌症新药的研发。以2-氨基吡嗪为起始原料,与N-卤代丁二酰亚胺发生卤代反应,与N,N-二甲基甲酰胺二甲基缩醛制备亚胺化合物,再和溴乙酸乙酯缩合成环制备6-卤代咪唑并[1,2-a]吡嗪-3-甲酸乙酯,再与氨水氨解共4步反应合成6-卤代咪唑并[1,2-a]吡嗪-3-甲酰胺,总收率为50.7～54.2%。产物结构经IR、~1H NMR、~(13)C NMR、元素分析进行了表征。此合成路线具有原料易得、操作简单、成本低廉、产率较高、避免柱层析分离纯化、更适合工业化放大生产的特点。     

Total Synthesis of 4′′‐O‐Acetylmananthoside B Part II: Synthesis of the Disaccharide Fragment

A disaccharide compound, p‐methoxyphenyl 2,3,4‐tri‐O‐benzyl‐β‐L‐arabinopyranosyl‐(1→6)‐2‐O‐benzyl‐3,4‐di‐O‐acetyl‐β‐D‐galactopyranoside ( 17 ), was successfully synthesized from two monosaccharides L‐arabinose and D‐galactose and fully characterized. This compound can be used to build a natural product 4″‐O‐acetylmanan thoside B, which was isolated from the leaves and stems of a kind of Vietnamese Acanthaceae Justicia patentiflora.     

Synthesis of benzyl O-(2,3,3''''-tri-O-acetyl-β-D-apiofuranosyl)-(1→3)-2,4-di-O-benzoyl-α-D-xylopyranoside and its X-ray structure

The protected apiose-containing disaccharide, benzyl O-(2,3, 3'-tri-O-acetyl-β-D-apiofuranosyl)-( 1→3)-2, 4-di-O-benzoyl-α-D-xylopyranoside, was synthesized and its X-ray structure provided.     

Synthesis of Cryptococcus neoformans Capsular Polysaccharide Structures. Part V: Construction of Glucuronic Acid‐Containing Thioglycoside Donor Blocks

Abstract

Glucuronic acid‐containing di‐ and trisaccharide thioglycoside building blocks, ethyl (benzyl 2,3,4‐tri‐O‐benzyl‐β‐D‐glucopyranosyluronate)‐(1 → 2)‐3‐O‐allyl‐4,6‐di‐O‐benzyl‐1‐thio‐α‐D‐mannopyranoside, ethyl (benzyl 2,3,4‐tri‐O‐benzyl‐β‐D‐glucopyranosyluronate)‐(1 → 2)‐6‐O‐acetyl‐3‐O‐allyl‐4‐O‐benzyl‐1‐thio‐α‐D‐mannopyranoside and ethyl (2,3,4‐tri‐O‐benzyl‐β‐D‐xylopyranosyl)‐(1 → 4)‐[(benzyl 2,3,4‐tri‐O‐benzyl‐β‐D‐glucopyranosyluronate)‐(1 → 2)]‐3‐O‐allyl‐6‐O‐benzyl‐1‐thio‐α‐D‐mannopyranoside, corresponding to repetitive structures in the capsular polysaccharide (CPS) of Cryptococcus neoformans, have been synthesized. The blocks contain an orthogonal allyl group in the 3‐position of the mannose residue to allow formation of the (1 → 3)‐linked mannan backbone of the CPS and benzyl ethers as persistent protecting groups to facilitate access to acetylated target structures. The glucuronic acid moiety was introduced using an acetylated trichloroacetimidate donor and the xylose residue employing the benzoylated bromo sugar to ensure β‐selectivity in the couplings. Exchange to benzyl protecting groups was then performed at the di‐ or trisaccharide level. Assembly of suitable blocks employing DMTST as promoter in diethyl ether then afforded, in high yield and with stereoselectivity, a protected pentasaccharide corresponding to a C. neoformans serotype D CPS structure.     

保护的几丁寡糖及结构类似物的合成：复杂氨基寡糖合成的通用方法

建立了逐步合成具有重要生物活性的2-脱氧-2-氨基葡萄糖寡糖链的通用方法。采用邻苯二甲酰基保护氨基、硫代苯基为还原末端的离去基团,以氨基葡萄糖为起始原料,几种保护的几丁寡糖及结构类似物被合成：3-O-乙酰基-4,6-O-亚苄基-2-脱氧-2-邻苯二甲酰亚氨基-b-D-吡喃葡萄糖-（1→4）-（3-O-乙酰基-6-O-苄基-2-脱氧-2-邻苯二甲酰亚氨基）-b-D-吡喃葡萄糖甲苷（4）、3-O-乙酰基-4,6-O-亚苄基-2-脱氧-2-邻苯二甲酰亚氨基-b-D-吡喃葡萄糖-（1→4）-（3-O-乙酰基-6-O-苄基-2-脱氧-2-邻苯二甲酰亚氨基-b-D-吡喃葡萄糖）-（1→4）-（3-O-乙酰基-6-O-苄基-2-脱氧-2-邻苯二甲酰亚氨基）-b-D-吡喃葡萄糖甲苷（6）、3-O-乙酰基-4,6-O-亚苄基-2-脱氧-2-邻苯二甲酰亚氨基-b-D-吡喃葡萄糖-（1→3）-（4,6-O-亚苄基-2-脱氧-2-邻苯二甲酰亚氨基）-b-D-吡喃葡萄糖甲苷（8）、3-O-乙酰基-4,6-O-亚苄基-2-脱氧-2-邻苯二甲酰亚氨基-b-D-吡喃葡萄糖-（1→3）-（4,6-O-亚苄基-2-脱氧-2-邻苯二甲酰亚氨基-b-D-吡喃葡萄糖）- （1→3）-（4,6-O-亚苄基-2-脱氧-2-邻苯二甲酰亚氨基）- b-D-吡喃葡萄糖甲苷（10）。所合成化合物通过核磁共振和质谱分析确证了其化学结构。     

2‐Amino‐8‐(2‐deoxy‐2‐fluoro‐β‐D‐arabinofuranosyl)imidazo[1,2‐a]‐1,3,5‐triazin‐4(8H)‐one: Synthesis and Conformation of a 5‐Aza‐7‐deazaguanine Fluoronucleoside

Nucleobase‐anion glycosylation of 2‐[(2‐methyl‐1‐oxopropyl)amino]imidazo[1,2‐a]‐1,3,5‐triazin‐4(8H)‐one ( 6 ) with 3,5‐di‐O‐benzoyl‐2‐deoxy‐2‐fluoro‐α‐D ‐arabinofuranosyl bromide ( 8 ) furnishes a mixture of the benzoyl‐protected anomeric 2‐amino‐8‐(2‐deoxy‐2‐fluoro‐D ‐arabinofuranosyl)imidazo[1,2‐a]‐1,3,5‐triazin‐4(8H)‐ones 9 / 10 in a ratio of ca. 1 : 1. After deprotection, the inseparable anomeric mixture 3 / 4 was silylated. The obtained 5‐O‐[(1,1‐dimethylethyl)diphenylsilyl] derivatives 11 and 12 were separated and desilylated affording the nucleoside 3 and its α‐D anomer 4 . Similar to 2′‐deoxy‐2′‐fluoroarabinoguanosine, the conformation of the sugar moiety is shifted from S towards N by the fluoro substituent in arabino configuration.     

Synthesis of a new 2‐amino‐glycan,poly‐(1→6)‐α‐D‐mannosamine,by ring‐opening polymerization of 1,6‐anhydro‐mannosamine derivatives

A stereoregular 2‐amino‐glycan composed of a mannosamine residue was prepared by ring‐opening polymerization of anhydro sugars. Two different monomers, 1,6‐anhydro‐2‐azido‐mannose derivative ( 3 ) and 1,6‐anhydro‐2‐(N, N‐dibenzylamino)‐mannose derivative ( 6 ), were synthesized and polymerized. Although 3 gave merely oligomers, 6 was promptly polymerized into high polymers of the number‐average molecular weight (M_n) of 2.3 × 10⁴ to 2.9 × 10⁴ with 1,6‐α stereoregularity. The differences of polymerizability of 3 and 6 from those of the corresponding glucose homologs were discussed. It was found that an N‐benzyl group is exceedingly suitable for protecting an amino group in the polymerization of anhydro sugars of a mannosamine type. The simultaneous removal of O‐ and N‐benzyl groups of the resulting polymers was achieved by using sodium in liquid ammonia to produce the first 2‐amino‐glycan, poly‐(1→6)‐α‐D ‐mannosamine, having high molecular weight through ring‐opening polymerization of anhydro sugars.© 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

具有β-(1→6)-半乳吡喃糖骨架和α-L-(1→3)-阿拉伯呋喃糖侧链的阿拉伯半乳寡糖的简易合成

4-Methoxyphenyl glycoside of β-D-Galp-(1→6)-[α-L-Araf-(1→3)-]β-D-Galp-(1→6)-β-D-Galp-(1→6)-{β-D-Galp-(1→6)-[α-L-Araf-(1→3)-]β-D-Galp-(1→6)-β-D-Galp-(1→6)-}2β-D-Galp-(1→6)-[α-L-Araf-(1→)3)-]β-D-Galp-(1→)6)-β-D-Galp was synthesized with 2,3,4,6-tetra-O-benzoyl-α-D-galactopyranosyl trichloroacetimidate (1), 6-O-acetyl-2,3,4-tri-O-benzoyl-α-D-galactopyranosyl trichloroacetimidate (11), 4-methoxyphenyl 3-O-allyl-2,4-tri-O-benzoyl-β-D-galactopyranoside (2),isopropyl 3-O-allyl-2,4-tri-O-benzoyl--thio-β-D-galactopyranoside (12),4-methoxyphenyl 2,3,4-tri-O-benzoyl-β-D-galactopyranoside (5), and 2,3,5-tri-O-benzoyl-α-L-arabinofuranosyl trichloroacetimidate (8) as the key synthons.     

Stereoselective Preparation of 3‐Amino‐2‐fluoro Carboxylic Acid Derivatives,and Their Incorporation in Tetrahydropyrimidin‐4(1H)‐ones,and in Open‐Chain and Cyclic β‐Peptides

The preparation of (2S,3S)‐ and (2R,3S)‐2‐fluoro and of (3S)‐2,2‐difluoro‐3‐amino carboxylic acid derivatives, 1 – 3 , from alanine, valine, leucine, threonine, and β³h‐alanine (Schemes 1 and 2, Table) is described. The stereochemical course of (diethylamino)sulfur trifluoride (DAST) reactions with N,N‐dibenzyl‐2‐amino‐3‐hydroxy and 3‐amino‐2‐hydroxy carboxylic acid esters is discussed (Fig. 1). The fluoro‐β‐amino acid residues have been incorporated into pyrimidinones ( 11 – 13 ; Fig. 2) and into cyclic β‐tri‐ and β‐tetrapeptides 17 – 19 and 21 – 23 (Scheme 3) with rigid skeletons, so that reliable structural data (bond lengths, bond angles, and Karplus parameters) can be obtained. β‐Hexapeptides Boc[(2S)‐β³hXaa(αF)]₆OBn and Boc[β³hXaa(α,αF₂)]₆‐OBn, 24 – 26 , with the side chains of Ala, Val, and Leu, have been synthesized (Scheme 4), and their CD spectra (Fig. 3) are discussed. Most compounds and many intermediates are fully characterized by IR‐ and ¹H‐, ¹³C‐ and ¹⁹F‐NMR spectroscopy, by MS spectrometry, and by elemental analyses, [α]_D and melting‐point values.     

Nucleosides XII.1 Synthesis of 5‐Modified Isoguanosines and Reinvestigation of 5′‐Deoxy‐N3,5′‐cycloisoguanosine

Isoguanosine ( 3 ) underwent a coupling reaction with diaryl disulfides in the presence of tri‐n‐butylphosphine when its 6‐amino group was protected by N,N‐dimethylaminomethylidene. The synthesis of 5′‐deoxy‐N³,5′‐cycloisoguanosine ( 6 ) and its 2′,3′‐O‐isopropylidene derivative ( 11 ) were accomplished in excellent yields from isoguanosines ( 3 & 10 ) in the presence of triphenylphospine and carbon tetrachloride in pyridine. Chlorination at the 5′‐position of isoguanosine ( 3 ) with thionyl chloride followed by the aqueous base‐promoted cyclization afforded the same product 6 . The structures were elucidated by spectroscopic analysis including IR, UV, 1‐D and 2‐D NMR.     

Hydrolysis Reaction of N-Phosphoryl-α-, β- and γ-amino Acids Studied by HPLC

The hydrolysis reactions of N-（O,O＇diisopropyl）phosphoryl-L-α-alanine （DIPP-L-α-Ala）, N-（O,O＇diisopropyl）- phosphoryl-D-α-alanine （DIPP-D-α-Ala）, N-（O,O＇-diisopropyl）phosphoryl-β-alanine （DIPP-β-Ala） and N-（O,O＇-diisopropyl）phosphoryl-γ-amino butyric acid （DIPP-γ-Aba）, were studied by HPLC and their hydrolysis reaction kinetic equations were obtained. Under acid conditions, the reaction rate of DIPP-L-α-Ala was close to that of DIPP-D-α-Ala and the same rule was true between DIPP-β-Ala and DIPP-γ-Aba. Meantime, the reaction rate of DIPP-L/D-α-Ala was as 10 times as that of DIPP-β-Ala or DIPP-γ-Aba. Under basic conditions, the hydrolysis reactions of DIPP-β-Ala and DIPP-γ-Aba almost did not take place and the reaction rate of DIPP-L/D-α-Ala was about 1/10 of that under acid conditions. Moreover, theoretical calculation further illuminated the differences of the hydrolysis rate from the view of energy. The results would provide some helpful clues to why nature chose a-amino acids but not other kinds of analogs as protein backbones.