Synthesis and chemistry of bridgehead allylsilanes. Stereoselective reactions with aldehydes

A type II intramolecular Diels-Alder reaction provides access to bicyclo[5.3.1] ring systems with an imbedded bridgehead allylsilane. The Lewis acid catalyzed reactions of these compounds with aldehydes proceed efficiently and with control of stereochemistry. [reaction: see text]     

Recyclization reactions of heterocycles XVIII. Synthesis and recyclization of thiazolium and benzothiazolium salts

A number of thiazolium salts were obtained, and their reaction with hydrazine was studied. On reaction with hydrazine the aryl-substituted thiazolium salts are recyclized to dihydro-l, 2, 4-triazines, whereas on reaction with monoalkylhydrazines they are converted to 4H, 5H-1, 2-4-triazinium salts; thiazolium salts are converted to hydrazidohydrazones on reaction with phenylhydrazine. Recyclization to the dihydro-sym-tetrazine system was observed for 2-phenyl-substituted benzothiazolium tosylate.See [1] for communication XVII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 635–640, May, 1976.     

Stereoselective radical reactions of some tartaric and glyceric acid derivatives

[reaction: see text] Free radicals generated by the decarboxylation of dimethoxydioxanecarboxylic acids derived from L-(+)-tartaric acid and L-glyceric acid added to some maleimides and acrylates with high stereoselectivity. This method provides easy access to some chiral building blocks.     

Synthesis and cytotoxicity of novel podophyllotoxin derivatives

In order to find novel synthetic antitumor agents with superior cytotoxicity and overcoming multidrug resistance,a novel series of 4β-N-substituted podophyllotoxin derivatives were synthesized and evaluated as potential antitumor agents.Seven novel podophyllotoxin derivatives were synthesized by linking 4β-amino-4-deoxypodophyllotoxin with N-substituted 5-methylindol-3- yl-glyoxyl chlorides and tested against K562 and K562/A02 using SRB methods in vitro,KB and KBV using MTT methods in vitro.     

Pyrazoles. XVIII. Synthesis of a novel tripyrazolyl by two consecutive cine substitution reactions

Preparation of the C-N coupled tripyrazolyl VII, by two consecutive cine substitution reactions starting from 1,4-dinitropyrazole and using pyrazole as a nucleophile, is described. Solvent dependent nitrations of 4-nitro-3(5)-(1′-pyrazolyl)pyrazole I are reported.     

去氢枞醇杂环类化合物的合成及细胞毒性研究

以去氢枞酸(1)为原料,经氢化铝锂还原得到去氢枞醇(2),2与氯乙酰氯在氮气保护和DMAP催化条件下反应合成中间产物去氢枞醇氯乙酸酯(3),3与杂环化合物经亲核取代反应合成了12个新型去氢枞醇杂环类化合物(4a ～41).利用IR、1H NMR、13C NMR和HR-MS等对目标化合物的结构进行表征,采用MTT法测试目...     

Synthesis and cytotoxicity of novel sansalvamide A derivatives

Described are the syntheses of 14 derivatives of the natural product Sansalvamide A, where two are more active against HCT 116 colon cancer cell lines than the natural product. These derivatives were synthesized using a combinatorial-type strategy that permits elucidation of the amino acid role in the cytotoxicity, and they lay the groundwork for development of new anticancer agents. [structure: see text]     

Phenothiazine syntheses. XVIII. 2-Aminophenothiazine derivatives

2-(-chloroacetylamido)-2-(-chloropropionylamido)-2-(benzylideneamino)- and 2-(o-hydroxybenzyllideneamino)phenothiazines are synthesized and reduced by lithium aluminum hydride to 2-ethylamino-, 2-propylamino-, 2-benzylamino-, and 2-(o-hydroxybenzylamino)phenothiazine. Reduction of the methyl and ethyl esters of phenothiazinecarbamic-2 acid by lithium aluminum hydride gives 2-methylaminophenothiazine.For Part XVII see [1].     

Synthesis and reactions of 1-bromocyclopropyltrimethylsilane derivatives

The title compounds derived from 1,1-dibromocyclopropanes are transformed into (1) cyclopropyltrimethylsilanes $\text{via}$ 1-trimethylsilylcyclopropyllithium species, (2) 1-alkylidenecyclopropanes by the Peterson-olefination, and (3) 1-acetyl(or 1-allyl)cyclopropylsilanes with dibutylcopperlithium and acetyl chloride (or allyl bromide).     

Stereoselective anti aldol reactions of erythrulose derivatives. Functionalized chiral d3 and d4 synthons

An improved procedure for the synthesis of anti aldols from protected erythrulose derivatives is reported. The preparation of functionalized d3 and d4 synthons with various stereochemical arrays by means of this methodology is described and subsequently applied to a stereoselective formal synthesis of the natural metabolite goniothalesdiol.     

Synthesis and cytotoxicity of pentacyclic triterpenes-aniline nitrogen mustard derivatives

To discover novel nitrogen mustards, the reported mustard pharmacophore was combined with natural pentacyclic triterpenes, which are characterized with pharmacological and structural diversity. Thus, six conjugates were synthesized with 1,2,3-triazole linking N,N-bis (2-chloroethyl)-1,4-phenylenediamine and oleanolic acid, ursolic acid, or glycyrrhetinic acid, and their biological activity was evaluated against tumor cell lines HeLa, BGC-823, BEL-7404, and NCI-H460 using the MTT assay. As a result, these conjugates showed some selective cytotoxicity to NCI-H460, though all their activity potency was moderate or weak in the four cell lines.     

Synthetic transformations of higher terpenoids: XVIII. Synthesis of optically active 9,10-anthraquinone derivatives

Retro-Diels-Alder decomposition of dodecahydro-endo-4b,12-ethenochrysene-1,4-diones obtained from a tricyclic diterpenoid, levopimaric acid, gave optically active 5-[2-(6-vinyl-2,6-dimethyl-2-carboxycyclohexyl) ethyl]-7-isopropyl-1,4-naphthoquinones which reacted with silyloxybutadienes to produce the corresponding 6- and 7-hydroxyanthraquinones, 5-furyl-7-hydroxytetrahydroanthraquinones, or 5-furyl-7-oxohexahydroanthraquinones. Condensation of the naphthoquinone derivatives with 5-isopropenyl-2,3-dihydrothiophene 1,1-dioxide resulted in the formation of 6,11-dioxodihydro- and 6,11-dioxohexahydroanthra[2,1-b]thiophene 3,3-dioxides. 6- and 7-Hydroxyanthraquinones were also obtained by reaction of dodecahydro-endo-4b,12-ethenochrysene-1,4-diones with Danishevsky diene, followed by cleavage of the polycyclic adducts. The cycloaddition of 5-[2-(-2-carboxy-2,6-dimethyl-6-vinylcyclohexyl)ethyl]-7-isopropyl-1,4-naphthoquinones in the presence of Lewis acids was characterized by increased regioselectivity.     

Synthesis and cytotoxicity studies of quinoline-3-carbonitrile derivatives

<正>A series of quinoline-3-carbonitrile derivatives were designed and synthesized.Their cytotoxicity in vitro against four cancer cell lines(A549,HT-29,MDA-MB-231 and SMMC-7721) were evaluated by standard MTT assay.The pharmacological results showed that most of the prepared compounds displayed excellent selective cytotoxicity toward SMMC-7721 cell line.Among them, compounds 7c,7e,11b,11f and 11g were more active than Gefitinb against SMMC-7721 cell line.     

Studies on organophosphorus compounds: XVIII. Synthesis and reactions of α-sulfonylphosphonates

A new facile synthetic method for the preparation of α-sulfonylphosphonates based on the phosphorylation of carbanion derived from sulfones bearing an active methylene group was described. Condensation of the resulting sulfonyl phosphorus ylides with aldehyde or ketone in situ gives α,β-unsaturated sulfones with satisfactory yields.     

Synthesis and reactions of some 5,6,7,8-tetrahydroquinoxaline derivatives

5,6,7,8-Tetrahydroquinoxaline derivatives containing an oxygen functionality in the 6-position were prepared by ring closure of suitable 2,3-disubstituted pyrazines such as 6 and 12 . The chemistry of these novel 5,6,7,8-tetrahydroquinoxalines is discussed.     

Synthesis of novel,azasugar-modified anthraquinone derivatives and their cytotoxicity

A series of novel, azasugar-modified 2-monosubstituted, 2,6- and 2,7-bissubstituted anthraquinone derivatives have been synthesized by the nucleophilic substitution of N-alkylamino azasugar with mono-, bis（2-chloroacetamido）anthraquinones. Their cytotoxic activities against HeLa and MCF-7 ceils were preliminarily evaluated and compound 9a with mono-azasugar pendant at 2-position showed similar activity to the control drug （Cisplatin）.     

Synthesis, characterization and cytotoxicity of new rotundic acid derivatives

Rotundic acid (RA, 1), a natural compound, exhibits potent tumor cell growth inhibiting properties. To date there are no reports on derivatives of RA. Furthermore, the 28-COOH position of RA might make it unstable and induced serious gastrointestinal side effects when it was applied in vivo. Therefore, in order to explore and make use of this compound, eight new amino acid derivatives of RA at the 28-COOH position were synthesized and evaluated for their cytotoxicities in vitro on three tumor cell lines including A375, HepG2 and NCI-H446. As a result, a few of these new amino acid derivatives showed stronger cytotoxicity. Compound 5a was found to have the best inhibition activity on the three tested human tumor cell lines with IC(50) values of less than 10 μM compared with RA treatment. Meanwhile, the cytotoxicity of compound 6b was significantly higher than that of RA on the A375 cell line and almost the same as RA on the HepG2 and NCI-H446 cell lines. Hence, compounds 5a and 6b may serve as potential lead compounds for the development of new anti-tumor drugs.     

Synthesis and reactions of trinitro-9,10-phenanthrenequinone derivatives

The reaction of 2,4,7-trinitro-9,10-phenanthrenequinone with CuCl in aqueous dimethylformamide or dimethyl sulfoxide at room temperature, followed by acidification, gave a stable red complex of 2,4,7-trinitro-9,10-dihydroxyphenanthrene with a solvent molecule. On heating in a polar aprotic solvent in the presence of CuCl or other metal salt, 2,4,7-trinitro-9,10-phenanthrenequinone underwent benzilic acid rearrangement with formation of 2,4,7-trinitrofluorenone. The nitration of 9,10-sulfuryldioxyphenanthrene and subsequent decomposition of cyclic sulfates afforded previously unknown 1,3,6-trinitro- and 1,8-dinitro-9,10-phenanthrenequinones.