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1.
We have found that activating either 2,3‐bis(2,3,4‐trimethoxyphenyl)cyclopropenone or 2,3‐bis(2,3,4‐trimethoxyphenyl)cyclopropene‐1‐thione with oxalyl bromide results in the formation of a species that promotes the glycosylation between 2,6‐dideoxy‐sugar hemiacetals and glycosyl acceptors in good yield and high α‐selectivity. Both reactions are mild and tolerate a number of sensitive functional groups including highly acid‐labile 2,3,6‐trideoxy‐sugar linkages.  相似文献   

2.
2,4‐Disubstituted 1‐benzoyl‐2,3‐dihydro‐1H‐1,5‐benzodiazepines were oxidized by m‐chloroperbenzoic acid (MCPBA) to produce 1a,3‐disubstituted 4‐benzoyl‐1a,2,3,4‐tetrahydro‐oxazirino[2,3‐a][1,5]benzodiazepines, a novel tricyclic heterocyclic system. However, 2,4‐disubstituted 2,3‐dihydro‐1H‐1,5‐benzodiazepines were oxidized by MCPBA under the same conditions to give a 2,4‐disubstituted 2,3‐dihydro‐2‐hydroxy‐1H‐1,5‐benzodiazepine or a 2,4‐disubstituted 3H‐1,5‐benzodiazepine, respectively. We propose a hydroxylation mechanism of peracid oxidation. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:158–162, 2000  相似文献   

3.
Photoirradiation of acetone solutions of 2,3‐diallyl‐6,7‐dihydro‐5H‐2a‐thia(2a‐SIV)‐2,3,4a, 7a‐tetraazacyclopent[cd]indene‐ 1,4(2H,3H)‐dithione ( 1 ) in the presence of excess thioacetic acid and thiobenzoic acid afforded addition products, 2,3‐bis(3‐acetylthiopropyl)‐ and 2,3‐bis(3‐benzoylthiopropyl)‐6,7‐dihydro‐5H‐2a‐thia(2a‐SIV)2,3,4a, 7a‐tetraazacyclopent[cd]indene‐1,4(2H,3H)‐dithiones, respectively, in good yields. These photoaddition reactions were facilitated by the addition of oxygen.  相似文献   

4.
For the convenient synthesis of (1→6)‐α‐D ‐glucopyranan, i. e., dextran ( 4 ), ring‐opening polymerization of 1,6‐anhydro‐2,3,4‐tri‐O‐allyl‐β‐D ‐glucopyranose ( 1 ) has been carried out using BF3·OEt2. With a ratio of [BF3·OEt2]/[ 1 ] = 0.5 at 0 °C for 140 h, the yield and Mn of the obtained polymer are 84.0% and 21 700, respectively. The polymer consists of (1→6)‐α‐linked 2,3,4‐tri‐O‐allyl‐D ‐glucopyranose ( 2 ) which is similar to the results for the cationic ring‐opening polymerization of 1,6‐anhydro‐2,3,4‐tri‐O‐methyl‐β‐D ‐glucopyranose and 1,6‐anhydro‐2,3,4‐tri‐O‐ethyl‐β‐D ‐glucopyranose. Polymer 2 was isomerized using tris(triphenylphosphine)‐chlororhodium as the catalyst in toluene/ethanol/water to yield polymeric 2,3,4‐tri‐O‐propenyl‐(1→6)‐α‐D ‐glucopyranan ( 3 ). Deprotection of the propenyl ether linkage of 3 was then performed using hydrochloric acid in acetone to give 4 .  相似文献   

5.
5,6‐Diaminopyrimidin‐2,4‐diol 1 was reacted with 1,4‐d ‐gluconolactone 2 , 6‐chloro‐4‐cyclopropyl‐7‐floro‐1,4‐dihydro‐1‐oxonaphthalen‐2‐carboxilic acid 4 , (3S)‐9,10‐difloro‐3,7‐dihydro‐3‐methyl‐7‐oxo‐2H‐[1,4]oxazino[2,3,4‐ij]quinolin‐6‐carboxylic acid 6 , and dimethylacetylendicarboxylate to afford 1‐(2,6‐dihydroxy‐9H‐purin‐8‐yl)‐sorbitol 3 , 7‐chloro‐1‐cyclopropyl‐6‐flouro‐3‐(2,6‐dihydroxy‐9H‐purin‐8‐yl)quinoline‐4(1H)‐one 5 , 9,10‐difluoro‐2,3‐dihydro‐6‐(2,6‐dihydroxy‐9H‐purin‐8‐yl)‐3‐methyl‐[1,4]oxazine[2,3,4‐ij]quinoline‐7‐one 7 , and (2,4‐dihydroxy‐6‐oxo‐5,8‐dihydro‐6H‐pteridine‐7‐yiliden)‐acetic acid methyl ester 9 , respectively. The synthesized compounds characterized by IR, 1H‐NMR, 13C‐NMR, GC‐mass, and elemental analysis.  相似文献   

6.
The reaction of 2,3,4‐tri‐O‐acetyl‐β‐D‐xylopyranosyl isothiocyanate ( 1 ) and 2‐amino‐4‐arylthiazoles ( 2 ) gave xylosylthioureas 3 . These thiourea derivatives reacted with alkyl/aryl amine in the presence of HgCl2 to give a new series of N‐alkyl/aryl‐N″‐(4‐arylthiazol‐2‐yl)‐N″‐xylosyl guanidines 4 . Some of the synthesized guanidines were screened for their biological activity. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:688–694, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20379  相似文献   

7.
An environmentally benign and efficient process for the preparation of 1‐(2,3,4‐trimethoxyphenyl)‐2‐substituted heterocyclic thio ethanone derivatives was achieved by the reactions of mercapto compounds with 2‐bromo‐1‐(2,3,4‐trimethoxyphenyl)ethanone in water mediated by indium in very high yields. Antifungal activities of the compounds were examined and moderate activity was obtained.  相似文献   

8.
An easy, highly efficient and a new convenient one‐pot, two‐step approach to the synthesis of 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐6‐methyl‐4‐(2‐oxo‐2‐phenylethoxy)‐3,4‐dihydro‐2H‐pyran‐2‐one is described. These compounds were synthesized from 3‐(3‐benzyl‐2‐(phenylimino)‐2,3‐dihydrothiazol‐4‐yl)‐4‐hydroxy‐6‐methyl‐3,4‐dihydro‐2H‐pyran‐2‐one and α‐bromoketones in good yields. The compounds 4 were synthesized by a multi‐component reaction between 1 , 2 , and 3 and the prominent features of this protocol are mild reaction conditions, operation simplicity, and good to high yields of products.  相似文献   

9.
3‐Acylaminofuro[2,3‐b]pyridine derivatives have been synthesized, and their behavior under acidic and basic conditions was studied. A new base‐catalyzed rearrangement of 3‐acylaminofuro[2,3‐b]pyridine derivatives into 3‐(oxazol‐4‐yl)pyridine‐2‐ones has been founded.  相似文献   

10.
A new and convenient method for the preparation of 2‐aryl‐2,3‐dihydro‐1,8‐naphthyridin‐4(1H)‐ones 4 has been developed. Thus, N‐{3‐[(2E)‐3‐arylprop‐2‐enoyl]pyridin‐2‐yl}‐2,2‐dimethylpropanamides 3 are synthesized from commercially available pyridin‐2‐amine using an easily performed three‐step sequence and are subjected to cyclization with deprotection under acidic conditions in H2O to give the desired products. Similarly, 2‐aryl‐2,3‐dihydro‐1,7‐naphthyridin‐4(1H)‐ones 8 and 2‐aryl‐2,3‐dihydro‐1,6‐naphthyridin‐4(1H)‐ones 12 can be prepared from pyridin‐3‐amine and pyridin‐4‐amine, respectively.  相似文献   

11.
A new and facile method for the general preparation of 3‐alkoxy‐2,3‐dihydro‐1H‐isoindol‐1‐ones has been developed. Thus, the reaction of 2‐(azidomethyl)benzoates with NaH affords, after workup with H2O, 3‐alkoxy‐2,3‐dihydro‐1H‐isoindol‐1‐ones 2 . 2‐Substituted 3‐alkoxy‐2,3‐dihydro‐1H‐isoindol‐1‐ones 4 can be obtained by adding alkyl halides prior to workup with H2O.  相似文献   

12.
Several new 6‐amino‐ and 6,8‐diamino‐4‐aryl‐2,3‐dihydropyrimido[4,5‐b][1,4]diazepines were obtained from the reaction of 4,5,6‐triaminopyrimidine 1a and 2,4,5,6‐tetraaminopyrimidine 1b with one equivalent of 3‐dimethylaminopropiophenones 2 in absolute ethanol. Structure analysis of 6‐amino‐ and 6,8‐diamino‐4‐aryl‐2,3‐dihydropyrimido[4,5‐b][1,4]diazepines 3a‐i , determined by detailed nmr measurements, reveals a high regioselectivity of this reaction.  相似文献   

13.
Previously synthesized 2‐(3′‐chloro‐5′,6′‐dicyanopyrazin‐2′‐yl)cyclopentan‐1‐one 1 , obtained from the reaction of 2,3‐dichloro‐5,6‐dicyanopyrazine with 1‐pyrrolidino‐1‐cyclopentene, was further reacted with primary alkylamines to give mixtures of diastereomer of 5‐alkyl‐2,3‐dicyano‐5a,8a‐dihy‐dro‐5a‐hydroxycyclopentano[1′,2′:4,5]pyrrolo[2,3‐b]pyrazines 3a‐h in high yield. The reaction of 2‐alkylamino‐3‐chloro‐5,6‐dicyanopyrazine with 1‐pyrrolidino‐1‐cyclohexene gave 5‐alkyl‐2,3‐dicyanocyclopentano[1′,2′:4,5]pyrrolo[2,3‐b]pyrazines 5a‐b together with 5‐alkylamino‐2,3‐dicyano‐6‐pyrrolidinopyrazines 6a‐b . The products prepared are all of interest as potential pesticides and new fluorescent chromophores.  相似文献   

14.
An efficient and convenient synthesis of a new series of 2‐{(6H‐indolo[2,3‐b]quinoxalin‐6‐yl)methyl}‐5‐aryl‐1,3,4‐oxadiazoles from readily available 1,2‐diaminobenzene and isatins under microwave irradiation conditions was disclosed. The 6‐{(5‐aryl‐1,3,4‐oxadiazol‐2‐yl)methyl}‐6H‐indolo[2,3‐b]quinoxalines were also prepared by the thermal cyclo‐condensation reaction of 2‐(6H‐indolo[2,3‐b]quinoxalin‐6‐yl)acetohydrazides with carboxylic acids in refluxing POCl3. The microwave‐assisted synthesis was rapid and resulted in higher yield of the products at lower operating temperature with reduced waste generation in comparison with the thermal reaction protocol.  相似文献   

15.
An efficient two‐step synthesis of novel 3‐(5‐amino‐[1,3,4]thiadiazol‐2‐yl)‐2H‐pyrano[2,3‐c]pyridine‐2‐ones was developed. In the first step, a new 2H‐pyrano[2,3‐c]pyridine‐3‐carboxamide 5 was prepared by Knoevenagel condensation of pyridoxal hydrochloride with cyanoacetamide. In the second step, the reaction of carboxamide 5 with a series of N4‐substituted thiosemicarbazides yielded a library of 35 dis crete compounds 8 {1–35} in high yields. The intermolecular recyclization mechanism leading to these products is discussed.  相似文献   

16.
Regarding to the importance of thieno[2,3‐b]thiophens and isothiocyanaetes reactiveties in the physical, chemical and pharmaceutical fields, this study has been undertaken to prepare the target compound 5‐cyano‐2‐carbethoxythieno[2,3‐b]thiophenyl‐3,4‐diisothiocyanates via a safe method. The formed isothiocyanates derivative was reacted with aromatic amines, acid hydrazied and some active methylene groups, followed by cyclization reaction for the formed intermediates to give new series of heterocyclic compounds  相似文献   

17.
An easy, fast, and cheap way for the synthesis of the new 3,5‐dioxo‐thiazolo[2,3‐a] pyrimidine‐6‐carbonitriles and 4,6‐dioxo‐pyrimido[2,1‐b][1,3]thiazine‐7‐carbonitriles using epoxides α‐functionalized.  相似文献   

18.
A simple and efficient one‐pot synthesis of alkyl 2‐(alkyl)‐4‐methyl‐2‐thioxo‐2,3‐dihydrothiazole‐5‐carboxylates from the reaction of primary alkylamines and carbon disulfide in the presence of 2‐chloro‐1,3‐dicarbonyl compounds is described. This new protocol has several advantages such as lack of necessity of the catalyst, good yields, mild conditions and short times for reaction.  相似文献   

19.
The synthesis of the title compounds 5H, 11H‐pyrido[2′,3′:2,3]thiopyrano[4,3‐b]indoles was accomplished by the Fischer indole cyclization of some 2,3‐dihydrothiopyrano[2,3‐b]pyridin‐4(4H)‐one phenylhydrazones and 7‐methyl‐2,3‐dihydrothiopyrano[2,3‐b]pyridin‐4(4H)‐one phenylhydrazones. The synthesis of the new 2,3‐dihydrothiopyrano[2,3‐b]pyridin‐4(4H)‐one, which was used as one of the starting compounds, is also described.  相似文献   

20.
Under phase transfer catalysis conditions, 6‐amino‐4‐phenyl‐2‐thioxo‐1,2‐dihydropyridine‐3,5‐dicarbonitrile ( 1 ) was allowed to react with halo compounds, acrylonitrile, chloroacetyl chloride, ethyl cyanoacetate, formamide, triethylorthoformate, or formic acid to give new derivatives of fused pyridines 2–22, respectively. Acetylation of compound 1 using acetic anhydride afforded product 23 , which in turn underwent intramolecular cyclization in pyridine to give the corresponding pyrido[2,3‐d]pyrimidine 24 .  相似文献   

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