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1.
报道了双木脂素threo-(±)-开环异落叶松脂醇二阿魏酸酯的全合成. 以香草醛为原料, 经过两步Stobbe反应构建木脂素骨架, 然后再用LiAlH4还原、加氢后, 产物经柱层析分离, 得到2个异构体meso-和threo-(±)-开环落叶松脂素; 根据其NMR, IR和HRMS等谱图确认发现, 极性较小的产物threo-(±)-开环落叶松脂素为合成的关键中间体. threo-(±)-开环落叶松脂素与甲氧甲基(MOM)保护的阿魏酸缩合得到目标产物threo-(±)-开环异落叶松脂醇二阿魏酸酯. 合成采用汇聚法, 经11步, 以约8%的总产率得到了目标产物. 该合成方法具有原料价廉易得及操作简便的优点, 并具有一定的实用价值. 相似文献
2.
以α-环柠檬醛(1)为A环合成子,以季盐(2)为C环合成子,经缩合及分子内环化反应得到关键中间体(5).为引入乙基,进行了Friedel-Crafts反应和脱氧反应等,共经7步反应得到了(±)-12-乙基-13-甲氧基-8,11,13-罗汉松三烯-7-酮[(±)-nimbonone](9)及(±)-12-乙基-13-甲氧基-8,11,13-罗汉松三烯(10). 相似文献
3.
以3-乙氧基-2-环己烯酮羰基邻位芳基化反应与Tsuji-Trost反应的串联反应作为关键步骤来构筑季碳中心, 完成了番杏科生物碱Mesembrine的全合成. 从商品化原料出发经6步反应以17.8%的总收率合成得到(±)-Mesembrine. 相似文献
4.
以2,4-二氧代戊酸甲酯(1)和1,5-二甲基-6-亚甲基环己烯(2)为原料,通过[2+2]光环加成和retro-Benzilicacid重排,合成了具有螺[4,5]癸烷结构的岩兰烷基本碳架的化合物3.用锌粉选择还原五元环上碳碳双键得螺环二酮(4),对环外羰基实施保护并将环上酮基转化为亚甲基得到重要的合成前体6,经与甲基溴化镁的格氏反应生成混合的标题化合物.利用羟基和异氰酸苯酯的反应生成一对N-苯基氨基甲酸酯异构体(12),二者分离后经四氢铝锂还原,完成了螺环倍半萜(±)-茅苍术醇和(±)-沉香螺醇的全合成. 相似文献
5.
从黄花木中分离得到5种化合物,经化学和光谱方法鉴定它们为:野决明碱、安那吉碱、金雀花碱、β-谷甾醇及1新化合物5-α-羟基-7,17-脱氢异羽扇豆碱。研究结果表明,黄花木属、野决明属和沙冬青属植物在植物化学分类学上具有亲缘关系。 相似文献
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以香叶醇为起始原料,经多步反应完成了西松烷型大环二萜类天然产物(±)-Sinulariol-A的全合成.合成的关键步骤是醛5与丙烯酸甲酯经改进的Morita-Baylis-Hillman加成以及二价铬诱导的烯丙基氯化物与醛的分子内加成环化 相似文献
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9.
以醛1和5为起始原料,经几步反应后用Ag2O偶联,得到含苯并二氧六环骨架的化合物7,化合物7经过选择性保护酚羟基,再用NaIO4/OsO4(cat.)氧化断裂双键,得到关键中间体9,化合物9和10经过Wittig-Horner反应,并用苯硫酚和AIBN实现了顺式双键向反式的转化,脱去保护基后完成了具有新颖结构的天然产物(±)-Aiphanol(12)的合成. 相似文献
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In this paper we report on a efficient and flexible synthetic route towards the total syntheses of the dihydrocoumarine derivatives hydrangenol (1), phyllodulcin (1a) and macrophyllol (6b). The syntheses started with a readily available phosphonium salt 2 and suitable modified benzaldehydes 3/3a/3b resulting in 46 to 61% overall yields in three to four-steps sequences. The racemic products could be separated by chiral HPLC. The evidence of the (R)-enantiomer for sweetness could be demonstrated for 1a. 相似文献
12.
The total syntheses of dichroanone and dichroanal B, as well as the formal syntheses of taiwaniaquinol B and taiwaniaquinone D, are reported. 相似文献
13.
Tsuyoshi Taniguchi 《Tetrahedron》2008,64(37):8773-8779
A total synthesis of (±)-stemonamide and (±)-isostemonamide has been achieved by using a radical cascade that involves two endo-selective cyclizations. (±)-Stemonamine and (±)-isostemonamine are synthesized by chemoselective reduction of (±)-stemonamide and (±)-isostemonamide, respectively. 相似文献
14.
Concise total syntheses of (±)isopaucifloral F, (±)quadrangularin A, and (±)pallidol, starting from commercially available 3,5-dimethoxybenzoic acid, have been achieved by a sequential process. The overall synthetic strategy involves Nazarov cyclization, Ramberg-Backlund olefination, and Friedel-Crafts alkylation. 相似文献
15.
Lokesh Chandra Pati 《Tetrahedron letters》2004,45(51):9451-9453
The stereoselective total synthesis of (±)-pisiferol (1) and (±)-pisiferal (2) has been successfully accomplished using the trans-octahydrophenanthrene derivative 20 as a key intermediate. Intramolecular cyclisation of the diazoketone 15 followed by catalytic hydrogenation provided, stereoselectively, the keto-ester 17 which was converted into the acetate 20 through the intermediates 18 and 19. 相似文献
16.
Total synthesis of α-herbertenol, β-herbertenol and 1,13-herbertenediol, employing a Claisen rearrangement and ring-closing metathesis as key reactions for the generation of the cyclopentane containing vicinal quaternary carbons, has been described. 相似文献
17.
Sajal Kanti Mal 《Tetrahedron》2004,60(12):2805-2811
A new approach for a short and efficient synthesis of common cyclohexenone intermediate towards the total synthesis of some furosesquiterpenes and their analogues are described. Regioselective alkylation of Hagemann's ester with 2/3-furyl-2-ethyl bromide followed by hydrolysis cum in situ decarboxylation and 1,4-addition with Gilman's reagent produced the cyclohexanone derivatives which have been utilized for total synthesis of (±) isopallescensin-A, (±) 10-desmethylpallescensin-A, (±) 5-desmethyl-4,5-dehydromicrocionin-1 and (±) isopallescensin-1. 相似文献
18.
T. PonpandianS. Muthusubramanian 《Tetrahedron letters》2011,52(13):1520-1522
A new route to synthesise (±)-thalictroidine and (±)-hygrine by tandem SN2-Micheal reaction is described. 相似文献
19.
P. Srinivas D. Srinivasa Reddy P.K. Dubey Parthasarathi Das 《Tetrahedron letters》2008,49(42):6084-6086
A new and efficient route to the family of eremophilanes is reported. Key steps are the highly stereocontrolled Diels-Alder reaction and aldol condensation to furnish a cis-decalin system with the desired stereochemistry present in the eremophilane family of natural products. This approach is general and was utilized for the synthesis of (±)-eremophilenolide, (±)-eremophiledinone, and (±)-deoxyeremopetasidione. 相似文献
20.
Samir Kumar Mandal 《Tetrahedron》2008,64(49):11050-11057
A radical-promoted synthesis of 3,4-dihydroisocoumarins has been achieved in moderate to good yields using titanocene(III) chloride (Cp2TiCl) as the radical initiator. The total synthesis of four naturally occurring dihydrocoumarins hydrangenol, phyllodulcin, macrophyllol and thunberginol G has been accomplished using the radical technology. Cp2TiCl was prepared in situ from commercially available titanocene dichloride (Cp2TiCl2) and Zn-dust in THF under argon. 相似文献