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1.
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
2.
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
3.
A straightforward synthesis of (±)-coerulescine and (±)-horsfiline has been established from 3-formyl-3-phenylpyrrolidine employing 4-hydroxypiperidine as the starting material. There are two remarkable steps for the synthesis of (±)-coerulescine and (±)-horsfiline. One is the rapid access to produce 3-formyl-3-phenylpyrrolidine by Lewis acid-catalyzed rearrangement of 3,4-dihydroxy-4-phenylpiperidine. The other key step is an intramolecular electrophilic cyclization from 3-benzylcarbamoyl-3-phenylpyrrolidine to the 3,3-spirocyclic 2-oxindole ring skeleton. 相似文献
4.
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
5.
Hyoungsu KimHoon Bae Sanghee KimDeukjoon Kim Dongjoo Lee Robert S. Paton 《Tetrahedron》2011,67(51):10017-10025
A general strategy for the synthesis of both trans/syn- and trans/anti-sphenolobane diterpenes has been developed, which utilizes an intramolecular ester enolate alkylation (IEEA) as a key step. A stereoselective total synthesis of (±)-tormesol (1), an unusual trans/syn-sphenolobane diterpene, was accomplished in 18 steps in 4.1% overall yield from readily available aldehyde 16. 相似文献
6.
Total synthesis of (±)-brazilin has been accomplished. m-CPBA epoxidation of allyl alcohol 10 and epoxy opening reaction mediated by m-chlorobenzoic acid, formed in situ as a byproduct, gave advanced intermediate diol 14. O-alkylation and cyclization gave phenol 6 which enabled the formal synthesis of (±)-brazilein and (±)-brazilide A. 相似文献
7.
A five-step and protecting group free synthesis of (±)-columbianetin from cyclohexane-1,3-dione is reported. The former compound was converted into its p-hydroxycinnamate derivative, (±)-angelmarin, using Coster’s esterification procedure. Efforts to modify the synthesis so as to prepare angelmarin and columbianetin in an enantioselective manner are described. 相似文献
8.
Fu-Min Zhang Jian-Dong Liu Xiao-Hui Fan Lei Shi Xiang-Dong Hu Shao-Hua Wang Yong-Qiang Zhang 《Tetrahedron》2006,62(40):9446-9455
A general strategy for synthesizing the crinine-type Amaryllidaceae alkaloids was developed. And total syntheses of four representative crinine-type Amaryllidaceae alkaloids: (±)-haemanthidine, (±)-pretazettine, (±)-tazettine, and (±)-crinamine, were accomplished via a common intermediate 17. This crucial precursor was achieved on the basis of the NBS-promoted semipinacol rearrangement recently developed by our group and an intramolecular Michael addition, which efficiently constructed the sterically congested quaternary carbon center and the hydroindole skeleton of the crinine-type alkaloids, respectively. 相似文献
9.
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
10.
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
11.
A convergent synthesis towards (±)-brazilin and (±)-brazilane has been reported from 3,4-dimethoxy benzaldehyde in <15 reaction steps. Palladium(II)-catalysed intramolecular Friedel–Crafts cyclisation and Lewis acid supported intermolecular Friedel–Crafts alkylation reactions have been demonstrated. A tetracyclic substituted indane common key intermediate is employed to furnish the desired two molecules in good to excellent yield. Pd(OH)2 has played a crucial role in the total synthesis of (±)-brazilane. 相似文献
12.
The syntheses of indolizidine alkaloids, i.e., (±)-coniceine, (±)-indolizidine 167B, (±)-5-butylindolizidine and (±)-monomorine I via Pummerer cyclization are described. The key step is the transformation of lactam sulfoxide to bicyclic lactam via the Pummerer cyclization. 相似文献
13.
Tapas PaulDebabrata Mukherjee 《Tetrahedron letters》2003,44(27):4985-4988
Stereocontrolled total syntheses of the bridged tricyclic ketones (±)-clovan-3-one (5) and (±)-epi-clovan-3-one (6) and a facile total synthesis of the tricyclic sesquiterpene (±)-pseudoclovene-A (3) have been successfully accomplished involving participation of an aryl intramolecular cyclisation of the bromophenol 11 as a key step. 相似文献
14.
Atsuo Nakazaki 《Tetrahedron》2006,62(26):6264-6271
The stereoselective total syntheses of (±)-α-vetispirene, (±)-hinesol, and (±)-β-vetivone were accomplished based on a Claisen rearrangement in an alkenyl bicyclic dihydropyran system. The most striking feature of this approach is that the Claisen rearrangement of bicyclic dihydropyran proceeds stereoselectively to provide a multi-functionalized spiro[4.5]decane, which is an efficient precursor for the synthesis of the vetivane sesquiterpenes. 相似文献
15.
A facile approach for the first total synthesis of two naturally occurring geranylated flavonoids, (±)-puyanin 1 and (±)-4′-O-methylbonannione 2 have been obtained with total yield 27% and 21%, respectively. The key steps were regioselective cyclization of geranylated tetrahydroxychalcone and regioselective geranylation of 2, 4, 6-trihydroxy- acetophenone. 相似文献
16.
Christian R. Razafindrabe Sylvain Aubry Marta Andriantsiferana Marc Lemaire 《Tetrahedron》2010,66(46):9061-9066
A synthesis of functionalized phenolic α-amino-alcohol (±)-13 as synthetic precursor of the catechol tetrahydroisoquinoline structure of phthalascidin 650 is disclosed. Starting from 3-methylcatechol 5, eight steps of synthesis give rise to the synthesis of phenolic α-amino-alcohol (±)-13 in 27% overall yield. This synthetic strategy involves the elaboration of fully functionalized aromatic aldehyde 8 and its transformation into a phenolic α-amino-alcohol (±)-13, through a Knoevenagel condensation, simultaneous reduction of nitroketene and ester functions and hydrogenolysis of the benzyl protecting group. The pentacycle (±)-18 was obtained after four additional steps. The Pictet-Spengler cyclisation between the phenolic α-amino-alcohol (±)-13 and N-protected α-amino-aldehyde 4 allowed to obtain (1,3′)-bis-tetrahydroisoquinoline 14 with N-methylated and N-Fmoc removed. The last step was a Swern oxidation for allowing an intramolecular condensation. 相似文献
17.
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
18.
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
19.
Total syntheses of two antimicrobial natural products (±)-cis-neocnidilide and (±)-trans-neocnidilide starting from a readily preparable cyclohexa[b]-fused 5-oxabicyclo[2.1.1]hexane derivative are presented. The diastereomeric tetrahydrofuran tricarboxylate epimers obtained from a BF3·OEt2 promoted Grob-type fragmentation of the oxa-bicycle derivative were converted into title natural products by employing pyridinium dichromate/acetic anhydride mediated bis-oxidative cleavage reaction. 相似文献
20.
Kazunori Takahashi 《Tetrahedron letters》2010,51(27):3542-3544
A formal synthesis of (±)-axamide-1 and (±)-axisonitrile-1 was achieved by using an intramolecular Hosomi-Sakurai reaction of the allylsilane derivative, as a key step, in which [(3-but-3-en-1-yl-3-methylcyclohex-1-en-1-yl)methyl](trimethyl)silane was transformed to a bicyclic compound possessing a core carbon framework under the oxidative dihydroxylation reaction conditions, in one step. 相似文献