亚硝基-烯(Nitroso-ene)反应的研究进展

烯丙基胺类化合物是有机化学中的重要合成中间体,亚硝基-烯(nitroso-ene)反应是合成这类化合物最为高效的方法之一.在一些天然产物和药物分子的全合成中,亚硝基-烯反应也往往作为关键步骤.这篇综述主要介绍了亚硝基–烯反应的发展、应用以及机理研究方面的进展.     

非洲粘虫拒食剂Warburgana类似物的合成研究-1-羟基-Drimane类中间体的合成

东非药用植物Warburgia属中分离得的Warburganal(1)对非洲粘虫有强烈的拒食作用,同时也有抗真菌、抗肿瘤、细胞毒素以及植物生长调节等活性。Warburganal及其一类物的全合成已曾报道。本文报道1-羟基-Warburganal(2)中间体的合成研究。     

生源启发下的喜树碱的简洁形式合成

以色胺和方便易得的乙基戊烯二醛盐为起始物,以简洁的步骤(最终实现喜树碱全合成共9步反应)完成了喜树碱的生源启发下的无保护基形式合成.合成路线涉及关键的Pictet-Spengler反应,分子内氧杂Diels-Alder反应高效构建单萜吲哚中间体,以及Winterfeldt高效仿生氧化吲哚合成喹啉酮结构.     

白屈菜红碱的全合成

以2,3-二甲氧基-6-溴苄醇(1)为起始原料,经过6步反应合成关键中间体2,3-二甲氧基-6-碘苯甲酸甲酯(7),通过金属钯催化下与中间体(8)的串联反应策略一步构筑了白屈菜红碱的B/C环,并以10步60.9%的总收率完成了白屈菜红碱的全合成,同时对关键的金属钯催化串联反应机理进行了初步探讨,为高效合成苯并[c]菲啶类生物碱提供了一条简便路线.     

1,6-二甲氧基-2-异丙基萘的新合成法

雷公藤内酯(Triptolide,1)是从卫矛科植物雷公藤(Tripterygium wilfordii Hook.f.)中分得的一种含三个环氧基的二萜内酯化合物,具有明显的抗小鼠白血病活性,它的毒性试验和临床试用亦已有报道。由于其独特的化学结构和生理活性,近年来全合成研究比较活跃。1980年Berchtold等首先报道了消旋雷公藤内酯的全合成,1,6-二甲氧基-2-异丙基萘2为合成中间体。     

Verbenachalcone的另法全合成

用一种新的简便方法对Verbenachalcone进行全合成, 针对目标物的结构特征, 将其切为2个合成片段, 即化合物4和6, 然后再将2个片段连接. 从对羟基苯甲醛(2)开始经过溴代、乙酰化、Ullmann反应、甲氧甲基化、羟醛缩合、脱保护和催化加氢等7步反应完成了标题化合物的全合成, 总收率为39.1%, 合成的关键步骤是3-溴-4-羟基苯甲醛(3)和香兰素进行的Ullmann反应. 关键中间体与最终产物的化学结构经¹H NMR, ¹³C NMR和ESI-MS等表征确认.     

秋水仙碱及其天然类似物(-)-N-乙酰秋水酚甲醚的不对称合成（英文）

采用相对简单的不对称合成方法,完成了秋水仙碱及其天然类似物(-)-N-乙酰秋水酚甲醚(NCME)的形式全合成.首先经简单醛、酮的Aldol缩合完成碳骨架的构筑,然后经手性亚磺酰胺诱导的不对称还原胺化反应,廉价、高效地合成了手性胺中间体;再经过高价碘试剂的氧化关环,构筑该类生物碱的三元环结构.本策略为该类生物碱的简便、快速合成提供了有效方法.     

(-)-(1R,2S)-肉豆蔻木脂素的不对称合成

报道了天然产物(-)-肉豆蔻木脂素的全合成. 以香草醛为起始原料, 经Wittig反应、LiAlH₄还原和Sharplass不对称双羟化等反应构建了苏式结构的中间体; 以焦性没食子酸为原料, 经Claisen重排反应制得另一种苯丙素片段; 2个中间体通过Mitsunobu反应, 缩合并使构型翻转, 得到赤式-(-)-肉豆蔻木脂素. 为赤式8-O-4′新木脂素的合成提供了一种新方法.     

3-羰基-10-去甲基-12-甲氧基-13-甲基罗汉松烷的全合成

以1,3-环己二酮为原料,经过甲基化反应和羰基保护构筑了A环合成子(5)。以邻甲基苯甲醚为原料,对位溴代、与环氧乙烷加成和进一步溴代等反应合成了C环合成子(9)。化合物5与9的格氏试剂偶联和关环反应完成目标产物3-羰基-10-去甲基-12-甲氧基-13-甲基罗汉松烷(11)的全合成。各中间体及目标产物结构均经红外光谱、核磁、质谱等表征,结果表明,成功实现了目标产物的合成。     

用反Diels-Alder反应合成天然产物

天然产物全合成主要在于发展有效的方法以组成碳骨架和立体控制引入必须的官能团。本文利用刚性分子三环癸二烯酮(1)为原料, 立体控制地引入取代基及官能团组成目标分子所需的碳骨架及官能团后进行反Diels-Alder反应释放出取代环戊烯酮, 从而进一步合成目标分子克罗莫酸C-I 2, D-I 3, F 4, B 7, 蚊皇识别信息素18,6-表蚊皇识别信息素19以及经30获得的32, 后者是全合成大环内酯生物碱27的关键中间体。用酶催化反应不对称乙酰化内消旋二醇24c得光学活性单乙酯24d(81%产率, 98.3%对映体过量值)。24d经过官能团转换可得(+)及(-)1, 从(-)1用相似的反应合成了光学活性蚊皇识别信息素(18)。     

A New Preparation of 1,3,3‐Trimethylbicyclo[2.2.2]octan‐2,6‐dione,a Never Isolated Intermediate in a Total Synthesis of (+)‐Norpatchoulenol. Formal Total Synthesis of (±)‐Iso‐Norpatchoulenol

A new preparation and the isolation and spectroscopic characterization of 1,3,3‐trimethylbicyclo[2.2.2]octan‐2,6‐dione ( 3 ), a so far elusive key intermediate in the Liu–Ralitsch total synthesis of (+)‐norpatchoulenol ((+)‐ 1a ), is described. The preparation of 3 constitutes also a formal total synthesis of (±)‐iso‐norpatchoulenol ((±)‐ 1b ), since 3 is correlated to an intermediate in the Monti and co‐workers synthesis of (±)‐ 1b .     

Stereocontrolled Total Synthesis of (+)‐trans‐Dihydronarciclasine

A highly stereoselective and efficient total synthesis of trans‐dihydronarciclasine from a readily available chiral starting material was developed. The synthesis defines two of the five stereogenic centers of the natural product by an amino acid ester–enolate Claisen rearrangement. The other three stereogenic centers are created in a highly stereocontrolled fashion via a six‐ring vinylogous ester intermediate, which is generated from the γ,δ‐unsaturated ester functional group of the Claisen rearrangement product in an efficient three‐step sequence. This concise total synthesis exemplifies the use of a highly regioselective Friedel–Crafts‐type cyclization to form the B ring via an isocyanate intermediate derived from an N‐Boc group, which is superior to the conventional method using an imino triflate intermediate. This same N‐Boc group is employed to give high selectivity in the Claisen rearrangement earlier in the sequence.     

Total Synthesis of Lycoricidine and Narciclasine by Chemical Dearomatization of Bromobenzene

The total synthesis of lycoricidine and narciclasine is enabled by an arenophile‐mediated dearomative dihydroxylation of bromobenzene. Subsequent transpositive Suzuki coupling and cycloreversion deliver a key biaryl dihydrodiol intermediate, which is rapidly converted into lycoricidine through site‐selective syn ‐1,4‐hydroxyamination and deprotection. The total synthesis of narciclasine is accomplished by the late‐stage, amide‐directed C−H hydroxylation of a lycoricidine intermediate. Moreover, the general applicability of this strategy to access dihydroxylated biphenyls is demonstrated with several examples.     

Concise and Enantioselective Total Synthesis of (−)‐Mehranine, (−)‐Methylenebismehranine,and Related Aspidosperma Alkaloids

We report an efficient and highly stereoselective strategy for the synthesis of Aspidosperma alkaloids based on the transannular cyclization of a chiral lactam precursor. Three new stereocenters are formed in this key step with excellent diastereoselectivity due to the conformational bias of the cyclization precursor, leading to a versatile pentacyclic intermediate. A subsequent stereoselective epoxidation followed by a mild formamide reduction enabled the first total synthesis of the Aspidosperma alkaloids (?)‐mehranine and (+)‐(6S,7S)‐dihydroxy‐N‐methylaspidospermidine. A late‐stage dimerization of (?)‐mehranine mediated by scandium trifluoromethanesulfonate completed the first total synthesis of (?)‐methylenebismehranine.     

Total Synthesis of the Polyoxygenated Sesquiterpenes Guignarderemophilanes C and D

The total syntheses of the neural anti‐inflammatory agents guignarderemophilanes C and D have been accomplished for the first time starting from γ‐hydroxy carvone in 15 and 14 steps, respectively. The presented synthetic route proceeds via a known intermediate, whose synthesis has been elaborated in our group in the course of the total synthesis of the sesquiterpenoid periconianone A. Key for the successful conversion of this intermediate into both targets was finding a suitable strategy to install the 1,2,3‐trihydroxylated A‐ring scaffold. For this purpose, we effectively employed a Mitsunobu inversion, epoxidation, and regioselective epoxide opening sequence, before the bicyclic ring system was constructed by an aldol condensation reaction on a sterically demanding substrate. Our reported synthesis set the stage for SAR studies to prepare even more potent compounds by modification and derivatization of the natural product's scaffold.     

A Scalable Total Synthesis of the Antitumor Agents Et‐743 and Lurbinectedin

An efficient and scalable approach is described for the total synthesis of the marine natural product Et‐743 and its derivative lubinectedin, which are valuable antitumor compounds. The method delivers 1.6 % overall yield in 26 total steps from Cbz‐protected (S)‐tyrosine. It features the use of a common advanced intermediate to create the right and left parts of these compounds, and a light‐mediated remote C?H bond activation to assemble a benzo[1,3]dioxole‐containing intermediate.     

First Total Synthesis of (−)‐Ligustiphenol

The first asymmetric total synthesis of (?)‐ligustiphenol is reported. The key step was conducted by exploiting a steric hindrance effect to control the formation of the adduct in a nucleophilic α‐Li‐phenolate addition reaction to the intermediate α‐oxo (?)‐menthyl ester. The synthesis is concise and feasible for the construction of analogous compounds and investigation of their biological activity.     

First Total Synthesis of N‐(3‐Guanidinopropyl)‐2‐(4‐hydroxyphenyl)‐2‐oxoacetamide

The first total synthesis of the α‐oxo amide‐based natural product, N‐(3‐guanidinopropyl)‐2‐(4‐hydroxyphenyl)‐2‐oxoacetamide ( 3 ), isolated from aqueous extracts of hydroid Campanularia sp., has been achieved. The α‐oxo amide 12 , prepared via the oxidative amidation of 1‐[4‐(benzyloxy)phenyl]‐2,2‐dibromoethanone ( 9a ) with 4‐{[(tert‐butyl)(dimethyl)silyl]oxy}butan‐1‐amine ( 10a ), has been used as the key intermediate in the total synthesis of 3 as HBr salt. On the way, an expeditious total synthesis of polyandrocarpamide C ( 2c ), isolated from marine ascidian Polyandrocarpa sp., was carried out in four steps.     

Radical Cyclization Route to the Stereoselective Synthesis of (+)‐trans‐Cognac Lactone and (+)‐trans‐Aerangis Lactone

Stereoselective total synthesis of two chiral lactones, (+)‐trans‐cognac lactone (1b) and (+)‐trans‐aerangis lactone (2c), has been achieved from the same intermediate using a radical‐based cyclization route.     

Asymmetric Total Syntheses of (−)‐α‐Lycorane, (−)‐Zephyranthine,and Formal Synthesis of (+)‐Clivonine

An asymmetric route to (−)‐α‐lycorane and (−)‐zephyranthine, and a formal total synthesis of (+)‐clivonine were achieved. A pivotal intermediate, which serves as a potent precursor for the divergent syntheses of these natural products, was accessed by a diastereoselective Pd‐catalyzed cinnamylation of an N ‐tert ‐butanesulfinyl imine.