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1.
The stereoselective total synthesis of decytospolides A and B, two naturally occurring pyran derivatives, has been achieved using D ‐mannitol as the starting material. The intramolecular oxa‐Michael reaction has been employed to construct the tetrahydropyran ring of the molecules and Weinreb amide formation to generate their side chain with a keto function. 相似文献
2.
Farid Naghiyev Ibrahim Mamedov Victor Khrustalev Namiq Shixaliyev Abel Maharramov 《中国化学会会志》2019,66(3):253-256
In this paper, we report a new synthesis route to 4H‐pyran derivatives and a plausible reaction mechanism. The interaction of 5‐acetyl‐2‐amino‐6‐methyl‐4‐phenyl‐4H‐pyran‐3‐carbonitrile with different active methylene reagents gives rise to the cleavage and subsequent recyclization of the pyran ring to afford the corresponding 4H‐pyran derivatives. 相似文献
3.
Surprising Reaction of 5‐(Phenylthio)‐ and 5‐(Methylthio)pent‐2‐en‐4‐inal with HCl Contrary to expectations (Scheme 1), 5‐(phenylthio)‐( 1a ) as well as 5‐(methylthio)pent‐2‐en‐4‐inal ( 1b ) react with a slight excess of HCl to give 2‐[bis(phenylthio)methyl]furan ( 17a , 77% yield) and 2‐[bis(methylthio)methyl]furan ( 17b , 61% yield), respectively. Structures 17a and 17b are supported by the results of an X‐ray crystal‐structure analysis, by spectroscopic data in comparison to those of model compounds, and by synthesis of 17a . This surprising reaction is tentatively explained by a mechanism (Scheme 4), including a special pyran→furan ring‐contraction sequence, which is in agreement with a labelling experiment. 相似文献
4.
Dr. Malte Brasholz Dr. James M. Macdonald Dr. Simon Saubern Dr. John H. Ryan Prof. Dr. Andrew B. Holmes 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(37):11471-11480
The total synthesis of the spiropiperidine alkaloid (?)‐perhydrohistrionicotoxin (perhydro‐HTX) 2 has been accomplished on a gram scale by employing both conventional batch chemistry as well as microreactor techniques. (S)‐(?)‐6‐Pentyltetrahydro‐pyran‐2‐one 8 underwent nucleophilic ring opening to afford the alcohol 10 , which was elaborated to the nitrone 13 . Protection of the nitrone as the 1,3‐adduct of styrene and side‐chain extension to the unsaturated nitrile afforded a precursor 17 , which underwent dipolar cycloreversion and 1,3‐dipolar cycloaddition to give the core spirocyclic precursor 18 that was converted into perhydro‐HTX 2 . The principal steps to the spirocycle 18 have successfully been transferred into flow mode by using different types of microreactors and in a telescoped fashion, allowing for a more rapid access to the histrionicotoxins and their analogues by continuous processing. 相似文献
5.
Nabila Aït‐Baziz Yahia Rachedi Maamer Hamdi Artur M. S. Silva F. Balegroune Roisnel Thierry N. Sellier 《Journal of heterocyclic chemistry》2004,41(4):587-591
The synthesis and reactivity studies of 4‐hydroxy‐6‐methyl‐3‐(5‐phenyl‐2E,4E‐pentadien‐1‐oyl)‐2H‐pyran‐2‐one 2 with nucleophiles are reported. Reactions of 2 with hydrazine derivatives gave new pyrazole‐type com pounds while the reaction with ortho‐phenylenediamines yielded 1,5‐benzodiazepines. The reaction of 2 with ethylamine implies the 2H‐pyran‐2‐one ring opening and the formation of a strong conjugated compound 3. 相似文献
6.
Jarno Kansikas Kaija Sipil 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(11):1383-1385
In the synthesis of 1‐phenyl‐2‐phenylthio‐2‐(tetrahydropyran‐2‐ylthio)ethanol, C19H22O2S2, four diastereoisomers are formed. Two non‐centrosymmetric enantiomeric forms which crystallize in space groups P212121 and Pna21 are presented. The former has an intramolecular hydrogen bond between the hydroxyl group and the O atom of the tetrahydropyran ring. In the latter isomer, the hydroxyl group forms an intermolecular hydrogen bond to the O atom of the tetrahydropyranyl group of a neighbouring molecule, joining the molecules into chains in the c‐axis direction; the O?O distances are 2.962 (4) and 2.764 (3) Å, respectively. The tetrahydropyran rings are in chair conformations in both isomers and the S side chain has an equatorial orientation in the former, but an axial orientation in the latter molecule. 相似文献
7.
Andrey N. Komogortsev Boris V. Lichitsky Alexander D. Tretyakov Artem N. Fakhrutdinov Arkady A. Dudinov Michail M. Krayushkin 《Journal of heterocyclic chemistry》2019,56(11):3081-3087
A convenient approach to the synthesis of the previously unknown 7H‐furo[3,2‐b]pyran‐7‐ones based on the intramolecular cyclization of carbonyl derivatives of 5‐hydroxy‐2‐methyl‐4H‐pyran‐4‐one has been elaborated. Key intermediates in the synthesis of the target 7H‐furo[3,2‐b]pyran‐7‐ones are 3‐hydroxy‐6‐methyl‐2‐(2‐oxo‐2‐arylethyl)‐4H‐pyran‐4‐ones. They are formed as a result of multicomponent condensation of 5‐hydroxy‐2‐methyl‐4H‐pyran‐4‐one with arylglyoxals and 4‐methoxyaniline. 相似文献
8.
Chang‐Song Yan Prof. Dr. Yu Peng Xiao‐Bo Xu Prof. Dr. Ya‐Wen Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(19):6039-6048
A nickel‐mediated intermolecular reductive cross‐coupling reaction of unactivated alkyl bromides and aryl iodides at room temperature has been developed and successfully extended to less explored intramolecular versions and tandem cyclization‐intermolecular cross‐coupling. Highly stereoselective (or stereospecific) synthesis of linear‐fused perhydrofuro[2,3‐b]furan (pyran) and spiroketal skeletons allows rapid access to these useful building blocks, which would be potentially valuable in the synthesis of relevant natural products. A rational explanation for the formation of contiguous stereogenic centers is given. 相似文献
9.
Carmen Varela Kristina Nilsson Mercedes Torneiro Antonio Mourio 《Helvetica chimica acta》2002,85(10):3251-3261
We present our first results on the synthesis of a new class of conformationally restricted vitamin D analogues bearing an extra five‐membered ring formed by linking C(18) and C(21). Two analogues of calcitriol ( 1 ) with unsaturations at the extra ring and the lateral chain were prepared. The triene system was introduced by the convergent Wittig Horner approach developed by Lythgoe [8] and F. Hoffmann‐La Roche [9]. The key steps in the preparation of the requisite fragments were: i) the long‐distance functionalization of ketal 11 at C(18), ii) the ring closure on 15 through an intramolecular aldol condensation to give the α,β‐unsaturated ketone 10 , and iii) the Pd‐catalyzed installation of the side chains. 相似文献
10.
Djamila Hikem‐Oukacha Yahïa Rachedi Maamar Hamdi Artur M.S. Silva 《Journal of heterocyclic chemistry》2011,48(1):31-37
An efficient synthesis of 3‐bromoacetyl‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one by bromination of dehydroacetic acid in glacial acetic acid is described. Novel 4‐hydroxy‐6‐methyl‐3‐(2‐substituted‐thiazol‐4‐yl)‐2H‐pyran‐2‐ones have been prepared from the reaction of 3‐bromoacetyl‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one with thioamides, thiourea, and diphenylthiocarbazone. The condensation reaction of 6‐methyl‐4H‐furo[3,2c]pyran‐3,4‐dione, obtained from the reaction of 3‐bromoacetyl‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one with aliphatic amines, with benzaldehydes and acetophenones led to novel 2‐arylidene‐6‐methyl‐2H‐furo[3,2‐c]pyran‐3,4‐diones and 6‐(2‐arylprop‐1‐enyl)‐2H‐furo[3,2‐c]pyran‐3,4‐diones. The structure of all compounds was established by elemental analysis, IR, NMR, and mass spectra. J. Heterocyclic Chem., 2011. 相似文献
11.
Synthesis of Prenyl‐ and Geranyl‐Substituted Carbazole Alkaloids by DIBAL‐H Promoted Reductive Pyran Ring Opening of Dialkylpyrano[3,2‐a]carbazoles
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Ronny Hesse Dr. Olga Kataeva Dr. Arndt W. Schmidt Prof. Dr. Hans‐Joachim Knölker 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(31):9504-9509
The DIBAL‐H promoted reductive pyran ring opening of dialkylpyrano[3,2‐a]carbazoles provides a direct access to a broad range of prenyl‐ and geranyl‐substituted carbazoles. Formation of a pyran ring followed by reductive ring opening represents a new method for the introduction of prenyl and geranyl groups. In the course of the present work, we achieved the first total syntheses of the following eight carbazole alkaloids: clauraila‐E, 7‐hydroxyheptaphylline, 7‐methoxyheptaphylline, mukoenine‐B (clausenatine‐A), mukoenine‐A (girinimbilol), mahanimbinol (mahanimbilol), euchrestine‐A, and isomurrayafoline‐B. 相似文献
12.
Furo[3,2‐c]pyran‐4‐ones, which possess a natural‐product skeleton, are synthesized via a simple, one‐pot, three‐component reaction of furan‐2,3‐diones with dialkyl acetylenedicarboxylates and Ph3P. 相似文献
13.
Jhillu Singh Yadav Dandekar Chandrakanth Yerragorla Gopala Rao Kontham Ravindar Basi V. Subba Reddy 《Helvetica chimica acta》2010,93(7):1432-1438
The stereoselective total synthesis of an antiproliferative and antifungal α‐pyrone natural product (6S)‐5,6‐dihydro‐6‐[(2R)‐2‐hydroxy‐6‐phenylhexyl]‐2H‐pyran‐2‐one is described. The key steps involved are the Prins cyclization, Mitsunobu reaction, and ring‐closing metathesis reaction. 相似文献
14.
Synthesis and Cytotoxic Activity of 1‐{3‐[1‐(5‐Organylsilylfuran‐2‐yl)silinan‐1‐yl]propyl}amines and Some Trimethylgermyl Analogues
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Dr. Luba Ignatovich Dr. Vitalijs Romanovs Velta Muravenko Ilze Sleiksha Dr. Jury Popelis Dr. Irina Shestakova 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(40):12786-12788
New highly cytotoxic 1‐{3‐[1‐(5‐organylsilyl‐furan‐2‐yl)silinan‐1‐yl]propyl}amines and some trimethylgermyl analogues (IC50 1–7 μg mL?1) have been synthesized by a hydrosilylation reaction of aliphatic and heterocyclic N‐allylamines in the presence of Speier’s catalyst. The effects of the silacycle, the element‐organic substituent in position 5 of the furan ring, and the structure of the amine on the cytotoxicity of the new compounds have been studied. 相似文献
15.
Dr. Nina Toelle Dr. Harald Weinstabl Dr. Tanja Gaich Prof. Dr. Johann Mulzer 《Angewandte Chemie (International ed. in English)》2014,53(15):3859-3862
An asymmetric synthesis of the diterpenoid 17‐deoxyprovidencin is described. Key steps include an aldol addition, a base‐catalyzed Wipf‐type furan formation, a Z‐selective ring‐closing metathesis for macrocyclization, a photochemical E/Z isomerization to a highly strained and conformationally restricted ring system, and the stereoselective formation of two epoxides on the ring. 相似文献
16.
Bicyclic acetal derivatives of the type 3 were prepared based either on a dihydroxyaldehyde 5 or an oxiranebutanal 6 (cf. Scheme 2). Lewis acid catalyzed reaction of the bicyclic acetal with allyltrimethylsilane introduces the side chain (as yet unfunctionalized) and sets the stereogenic centers at the tetrahydro‐2H‐pyran ring of the pederin moiety. 相似文献
17.
Synthesis,structure and biological activity of new 6,6‐dimethyl‐2‐oxo‐4‐{2‐[5‐organylsilyl(germyl)]furan(thiophen)‐2‐yl}vinyl‐5,6‐dihydro‐2H‐pyran‐3‐carbonitriles
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Luba Ignatovich Jana Spura Velta Muravenko Sergey Belyakov Juris Popelis Irina Shestakova Ilona Domrachova Anita Gulbe Zhanna Rudevica Ainars Leonchiks 《应用有机金属化学》2015,29(11):756-763
New 6,6‐dimethyl‐2‐oxo‐4‐{2‐[5‐alkylsilyl(germyl)]furan(thiophen)‐2‐yl}vinyl‐5,6‐dihydro‐2H‐pyran‐3‐carbonitriles (IC50: 1–6 µg ml?1) have been prepared by the condensation of corresponding silicon‐ and germanium‐containing furyl(thienyl)‐2‐carbaldehydes with 3‐cyano‐4,6,6‐trimethyl‐5,6‐dihydropyran‐2‐one using piperidine acetate as a catalyst. The obtained carbonitriles were identified using NMR (1H, 13C and 29Si) spectroscopy and GC‐MS. The structure of 6,6‐dimethyl‐2‐oxo‐4‐[2‐(5‐trimethylsilyl)thiophen‐2‐yl]‐5,6‐dihydro‐2H‐pyran‐3‐carbonitrile was studied using X‐ray diffractometry. The influences of the heterocycle and the structure of the organoelement substituent on cytotoxicity and on matrix metalloproteinase inhibition have been studied. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
18.
Polypyrrole/Fe3O4/CNT as a recyclable and highly efficient catalyst for one‐pot three‐component synthesis of pyran derivatives
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Polypyrrole (PPY)/Fe3O4/CNT has been synthesized and characterized by FT‐IR, TEM and SEM techniques and its catalytic activity has been evaluated in the synthesis of several series of pyran derivatives. Tetrahydrobenzo[b]pyranes, 4H‐pyran‐3‐carboxylates, 4H,5H‐pyrano[3,2‐c]chromenes and dihydropyrano[2,3‐c]pyrazoles have been successfully prepared from one‐pot three‐component condensation of aldehyde, malononitrile and active methylene‐containing compounds (dimedone /ethyl acetoacetate/4‐hydroxycoumarin/3‐methyl‐2‐pyrazoline‐5‐one) using PPY/Fe3O4/CNT as a new and reusable heterogeneous catalyst. The present method offer several advantages such as; high yields of products, short reaction times, easy work‐up procedure and easy separation of the catalyst from the reaction mixture due to its magnetic character. Furthermore, chemoselective synthesis of bis‐benzo[b]pyran from terephthalaldehyde can be achieved by this method. 相似文献
19.
A new enantioselective synthesis of furan‐2‐yl amines and amino acids is described, in which the key step is the oxazaborolidine‐catalyzed enantioselective reduction of O‐benzyl (E)‐ and (Z)‐furan‐2‐yl ketone oximes to the corresponding chiral amines. The chirality of the furan‐2‐yl amines is fully controlled by the appropriate choice of the geometrical isomer of the O‐benzyl oxime. Oxidation of the furan ring furnished amino acids in high yields. 相似文献
20.
Core‐Modified Analogues of Expanded Porphyrins Containing Rigid β,β′‐Linked o‐Phenylene Bridges
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Structural modifications that lead to the creation of π‐extended aromatic macrocyles involving a heterocyclic ring other than pyrrole and rigid β‐β′ linkages have not been well studied up to date. The rigidity caused by the conformational restriction would change the spectroscopic properties of the system as compared with those of the normal congeners. With these considerations, we have synthesized and fully characterized π‐extended, core modified expanded porphyrins bearing rigid bipyrrole units. Core‐modified naphthorubyrins were synthesized by the Lewis acid‐catalyzed condensation of naphthobipyrrole with thiophene/furan diols, whereas naphthosapphyrins were obtained by reacting 2,9‐diformyl‐naphthobipyrrole with 16‐thia/oxatripyrranes under mild reaction conditions. The core‐modified analogues of both naphthorubyrin and naphthosapphyrin displayed the aromatic character. The dithiarubyrin analogues showed a lack of conformational change as expected and displayed well‐resolved 1H NMR resonances at room temperature. On the other hand, the oxasapphyrin analogue adopts a furan‐inverted geometry, and the ring inversion is independent of the protonation state. The oxanaphthosapphyrin also exhibited a weak fluorescence emission at 613 nm. 相似文献