Synthesis of Ethyl 2‐Amino‐4‐benzoyl‐5‐oxo‐5,6‐dihydro‐4H‐pyrano[3,2‐c]quinoline‐3‐carboxylates by a One‐pot,Three‐Component Reaction in the Presence of TPAB

In this research, in order to synthesize a series of ethyl 2‐amino‐4‐benzoyl‐5‐oxo‐5,6‐dihydro‐4H‐pyrano[3,2‐c]quinoline‐3‐carboxylates, a green and an efficient method is proposed through one‐pot three‐component reaction of substituted arylglyoxals, ethyl cyanoacetate, and 4‐hydroxyquinolin‐2(1H)‐one in the presence of terapropylammonium bromide as a catalyst in good yields. All synthesized new substances were characterized by FTIR, ¹H‐NMR, and ¹³C‐NMR spectral data and elemental analysis.     

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

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.     

2‐Triazolylpyrimido[1,2,3‐cd]purine‐8,10‐diones via 1,3‐dipolar cycloadditions to 2‐ethynylpyrimido[1,2,3‐cd]purine‐8,10‐dione

This paper presents the synthesis of a series of 5,6‐dihydro‐4H,8H‐pyrimido[1,2,3‐cd]purine‐8,10(9H)‐dione ring system derivatives with a [1,2,3]triazole ring bonded in position 2. The procedure is based on cycloaddition of substituted alkyl azides to the terminal triple bond of 5,6‐dihydro‐2‐ethynyl‐9‐methyl‐4H,8H‐pyrimido[1,2,3‐cd]purine‐8,10(9H)‐dione ( 4 ). This cycloaddition produced two regioisomers ?5,6‐dihydro‐9‐methyl‐2‐(1‐substituted‐1H‐[1,2,3]triazol‐5‐yl)‐4H,8H‐pyrimido[1,2,3‐cd]purine‐8,10(9H)‐dione ( 7 ) and 2‐(1‐substituted‐1H‐[1,2,3]triazol‐4‐yl) derivative 8 . The required 2‐ethynyl deriva tive 4 was obtained from the starting 2‐unsubstituted compound 1 by bromination to yield the 2‐bromo derivative 2 , which was converted by Sonogashira reaction to trimethylsilylethyne 3 and finally, the protective trimethylsilyl group was removed by hydrolysis.     

New access to pyrazole,oxa(thia)diazole and oxadiazine derivatives

1,4‐Disubstituted thiosemicarbazides 1b–f reacted with ethenetetracarbonitrile ( 5 ) in di‐ methylformamide with formation of 2‐substituted 5‐phenyl‐1,3,4‐thiadiazoles 2a–f and 2‐substituted 5‐phenyl‐1,3,4‐oxadiazoles 4a–f . Upon addition of 5 to 1c–e in chlorobenzene, 3‐amino‐2‐benzoyl‐4,5,5‐tri‐ cyano‐2,5‐dihydro‐1H‐pyrazole‐1‐[N‐(4‐tricyanovi‐nyl)phenyl]carbothioamide ( 12 ), 5‐benzylamino‐, and 5‐allylamino‐4‐benzoyl‐2,3‐dihydro‐[1,3,4]thiadiazol‐ 2,2‐dicarbonitrile ( 13a,b ) and 5‐amino‐1‐benzoylpyrazole‐3,4‐dicarbonitrile ( 14 ) as well as 2‐phenyl‐ 4H‐[1,3,4]‐oxadiazine‐5,6‐dicarbonitrile ( 15 ) were formed. Rationales for the role of the solvent and the conversions observed are presented. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:12–19, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20071     

Reaction of cyclic imidates with α,β‐unsaturated esters: Synthesis of new pyrrolo[2,1‐b]‐1,3‐oxazine and pyrido[2,1‐b]‐1,3‐oxazine derivatives

The cycloaddition reaction of cyclic imidates, 2‐benzyl‐5,6‐dihydro‐4H‐1,3‐oxazines 1a , 1b , 1c , 1d , 1e , 1f , with dimethyl acetylenedicarboxylate 2 , trimethyl ethylenetricarboxylate 4 , or dimethyl 2‐(methoxymethylene)malonate 6 afforded new fused heterocyclic compounds, such as methyl (6‐oxo‐3,4‐dihydro‐2H‐pyrrolo[2,1‐b]‐1,3‐oxazin‐7‐ylidene)acetates 3a , 3b , 3c , 3d , 3e , 3f (71–79%), dimethyl 2‐(6‐oxo‐3,4,6,7‐tetrahydro‐2H‐pyrrolo[2,1‐b]‐1,3‐oxazin‐7‐yl)malonates 5b , 5c , 5d , 5e , 5f (43–71%), or methyl 6‐oxo‐3,4‐dihydro‐2H,6H‐pyrido[2,1‐b]‐1,3‐oxazine‐7‐carboxylates 7a , 7b , 7c , 7d , 7e , 7f (32–59%), respectively. In these reactions, 1a , 1b , 1c , 1d , 1e , 1f (cyclic imidates, iminoethers) functioned as their N,C‐tautomers (enaminoethers) 2 to α,β‐unsaturated esters 2 , 4, and 6 to give annulation products 3 , 5 , and 7 following to the elimination of methanol, respectively. J. Heterocyclic Chem., (2011).     

Synthesis anti‐fungal and anti‐bacterial screening of 3‐phenyl‐1,4,5‐trihydro‐pyrazol and 2, 4‐dihydro[ 1,2,4]‐triazol‐3‐one derivatives of 4‐hydroxy‐2‐oxo‐2H‐1‐benzopyran

4‐Hydroxy‐2‐oxo‐2H‐1‐benzopyran‐3‐carboxaldehydes 2a‐d are prepared from 4‐hydroxy‐2‐oxo‐2H‐1‐benzopyrans 1a‐d via the Vielsmeyer Haack reaction. The 4‐hydroxy‐2‐oxo‐3‐(3′oxo‐3′‐phenylprop‐1′‐enyl)‐2H‐1‐benzopyrans 3a‐d are obtained from 2a‐d via the Claisen reaction. Refluxing compounds 3a‐d with hydrazine hydrate gave the 3‐phenyl‐5‐(4‐hydroxy‐2‐oxo‐2H‐1‐benzopyran‐3‐yl)‐1,4,5‐trihydropyra‐zols 4a‐d . Stirring compounds 2a‐d with semicarbazide hydrochloride in acidic medium gave the 4‐hydroxy‐2‐oxo‐2H‐1‐benzopyran‐3‐aldehyde‐semicarbazone 5a‐d , which on cyclisation with ferric chloride hexahydrate gave the 5‐(4‐hydroxy‐2‐oxo‐2H‐1‐benzopyran‐3‐yl)‐2,4‐dihydro[1,2,4]triazol‐3‐ones 6a‐d . All these compounds show significant antibacterial activities.     

One‐Pot Synthesis of 4‐Substituted 3,4‐Dihydro‐3‐methoxyisocoumarins via Carboxylation of α‐Substituted 2‐Lithio‐β‐methoxystyrenes with Carbon Dioxide

A new type of isocoumarins (=1H‐isochromen‐1‐ones=1H‐2‐benzopyran‐1‐ones), 4‐substituted 3,4‐dihydro‐3‐methoxyisocoumarins 2 , can be obtained by a one‐pot process from α‐substituted 2‐bromo‐β‐methoxystyrenes 1 . Thus, lithium 2‐(1‐aryl(or methyl)‐2‐methoxyethenyl)benzoates are conveniently generated via the Br/Li exchange between 1 and BuLi, followed by the action of CO₂ on the resulting α‐substituted 2‐lithio‐β‐methoxystyrenes. Upon treating with concentrated HCl at room temperature, these lithium benzoates undergo lactonization to provide the desired 3,4‐dihydroisocoumarins 2 in relatively good yields.     

Diastereo‐ and Enantioselective Intramolecular [2+2] Photocycloaddition Reactions of 3‐(ω′‐Alkenyl)‐ and 3‐(ω′‐Alkenyloxy)‐Substituted 5,6‐Dihydro‐1H‐pyridin‐2‐ones

3‐(ω′‐Alkenyl)‐substituted 5,6‐dihydro‐1H‐pyridin‐2‐ones 2 – 4 were prepared as photocycloaddition precursors either by cross‐coupling from 3‐iodo‐5,6‐dihydro‐1H‐pyridin‐2‐one ( 8 ) or—more favorably—from the corresponding α‐(ω′‐alkenyl)‐substituted δ‐valerolactams 9 – 11 by a selenylation/elimination sequence (56–62 % overall yield). 3‐(ω′‐Alkenyloxy)‐substituted 5,6‐dihydro‐1H‐pyridin‐2‐ones 5 and 6 were accessible in 43 and 37 % overall yield from 3‐diazopiperidin‐2‐one ( 15 ) by an α,α‐chloroselenylation reaction at the 3‐position followed by nucleophilic displacement of a chloride ion with an ω‐alkenolate and oxidative elimination of selenoxide. Upon irradiation at λ=254 nm, the precursor compounds underwent a clean intramolecular [2+2] photocycloaddition reaction. Substrates 2 and 5 , tethered by a two‐atom chain, exclusively delivered the respective crossed products 19 and 20 , and substrates 3 , 5 , and 6 , tethered by longer chains, gave the straight products 21 – 23 . The completely regio‐ and diastereoselective photocycloaddition reactions proceeded in 63–83 % yield. Irradiation in the presence of the chiral templates (?)‐ 1 and (+)‐ 31 at ?75 °C in toluene rendered the reactions enantioselective with selectivities varying between 40 and 85 % ee. Truncated template rac‐ 31 was prepared as a noranalogue of the well‐established template 1 in eight steps and 56 % yield from the Kemp triacid ( 24 ). Subsequent resolution delivered the enantiomerically pure templates (?)‐ 31 and (+)‐ 31 . The outcome of the reactions is compared to the results achieved with 4‐substituted 5,6‐dihydro‐1H‐pyridin‐2‐ones and quinolones.     

Synthesis of New 1,3,4‐Oxadiazol,Thiadiazole, 1,2,4‐Triazole,and Arylidene Hydrazide Derivatives of 4‐Oxo‐1,4‐dihydroquinoline with Antimicrobial Evaluation

A series of substituted 1,3,4‐oxadiazole, 1,2,4‐triazole, and 1,3,4‐thiadiazole derivatives of the substituted 3‐carboethoxy‐1,4‐dihydro‐4‐oxoquinoline have been synthesized through the reaction of the key intermediate thiosemicarbazide derivatives with different reagents. N′‐Arylidene‐4‐oxo‐1,4‐dihydroquinoline‐3‐carbohydrazides were also synthesized through the condensation reaction of the corresponding hydrazides with the appropriate aldehydes. Antimicrobial activity of some of the synthesized compounds was evaluated.     

Heterocyclic synthesis: A convenient route to some 2‐mercepto 1,3,4‐oxadiazole and green chemistry microwave‐induced one‐pot synthesis of 2‐aryl 1,3,4‐oxadiazole in quinazolone and their antibacterial and antifungal activity

Several 6‐substituted‐3‐[(5‐mercepto‐1,3,4‐oxadiazol‐2‐yl)methyl]‐2‐substituted quinazolin‐4(3H)‐one or 6‐substituted‐3‐[4‐(5‐mercepto‐1,3,4‐oxadiazol‐2‐yl)phenyl]‐2‐substituedquinazolin‐4(3H)‐one 2(a‐l) and 6‐substituted‐3‐[(5‐phenyl‐1,3,4‐oxadiazol‐2‐yl)methyl]‐2‐substitutedquinazolin‐4(3H)‐one or 6‐substi‐tuted‐3‐[4‐(5‐phenyl‐1,3,4‐oxadiazol‐2‐yl) phenyl]‐2‐substitutedquinazolin‐4(3H)‐one 3(a‐l) were synthesized using conventional and microwave techniques respectively and were screened for antibacterial and antifungal activity.     

Annulation of o‐Aminoquinoxaline‐1,4‐dioxidenitrile with Ketonic Compounds Under Friedländer‐type Cyclocondensation and its Biological Evaluation

The reaction of compound 2‐amino‐3‐cyano‐6‐methylquinoxaline‐1,4‐dioxide with cyclohexanone and dimedone in dimethylformamide in the presence of anhydrous ZnCl₂ under Friedländer‐type cyclocondensation gave compounds 12‐amino‐9‐methyl‐1,2,3,4,12,12a‐hexahydroquinolino[2,3‐b]quinoxaline‐6,11‐dioxide ( 4 ), 7‐methyl‐4‐oxo‐3,4‐dihydro‐1H‐spiro[benzo[g]pteridine‐2,1′‐cyclohexane]5,10‐dioxide ( 5 ), and 12‐amino‐3,3,9‐trimethyl‐1‐oxo‐1,2,3,4,12,12a‐hexahydroquinolino[2,3‐b]quinoxaline‐6,11‐dioxide ( 6 ); (R)‐3′,3′,7‐trimethyl‐4,5′‐dioxo‐3,4‐dihydro‐1H‐spiro[benzo[g]pteridine‐2,1′‐cyclohexane]5,10‐dioxide ( 7 ) were achieved and evaluated their biological activity as antibacterial and antifungal activities and antitumor evaluation, and also, the density functional theory calculations were evaluated.     

An Innovative Protocol for the Synthesis of 3‐(Pyridin‐2‐yl)‐5‐sec‐aminobiphenyl‐4‐carbonitriles and 9,10‐Dihydro‐3‐(pyridine‐2‐yl)‐1‐sec‐aminophenanthrene‐2‐carbonitriles

Herein, we present an innovative, novel, and highly convenient protocol for the synthesis of 3‐(pyridin‐2‐yl)‐5‐sec‐aminobiphenyl‐4‐carbonitriles ( 6a , 6b , 6c , 6d , 6e , 6f , 6g ) and 9,10‐dihydro‐3‐(pyridine‐2‐yl)‐1‐sec‐aminophenanthrene‐2‐carbonitriles ( 10a , 10b , 10c , 10d , 10e ), which have been delineated from the reaction of 4‐sec‐amino‐2‐oxo‐6‐aryl‐2H‐pyran‐3‐carbonitrile ( 4a , 4b , 4c , 4d , 4e , 4f , 4g ) and 4‐sec‐amino‐2‐oxo‐5,6‐dihydro‐2H‐benzo[h]chromene‐3‐carbonitriles ( 9a , 9b , 9c , 9d , 9e ) with 2‐acetylpyridine ( 5 ) through the ring transformation reaction by using KOH/DMF system at RT. The salient feature of this procedure is to provide a transition metal‐free route for the synthesis of asymmetrical 1,3‐teraryls like 3‐(pyridin‐2‐yl)‐5‐sec‐aminobiphenyl‐4‐carbonitriles ( 6a , 6b , 6c , 6d , 6e , 6f , 6g ) and 9,10‐dihydro‐3‐(pyridine‐2‐yl)‐1‐sec‐aminophenanthrene‐2‐carbonitriles ( 10a , 10b , 10c , 10d , 10e ). The novelty of the reaction lies in the creation of an aromatic ring from 2H‐pyran‐2‐ones and 2H‐benzo[h]chromene‐3‐carbonitriles via two‐carbon insertion from 2‐acetylpyridine ( 5 ) used as a source of carbanion.     

Strategy to Construct Stair‐Shaped Partially Reduced Naphtho[1,2‐b]pyrano[2,3‐d]oxepines and Dinaphtho[1,2‐b,d]oxepines

A concise and efficient base‐induced synthesis of stair‐shaped, 4‐methylthio‐2‐oxo‐5,6‐dihydro‐2H‐naphtho[1,2‐b]pyran[2,3‐d]oxepine‐3‐carbonitriles ( 3 ) has been delineated by the reaction of 3,4‐dihydronaphtho[1,2‐b]oxepin‐5(2H)‐one ( 1 ) and methyl 2‐cyano‐3,3‐dimethylthioacrylate in DMSO using powdered KOH as a base at room temperature. Amination of 3 has been achieved by reaction with secondary amine in ethanol at reflux temperature to yield 4‐sec‐amino‐2‐oxo‐5,6‐dihydro‐2H‐naphtho[1,2‐b]pyran[2,3‐d]oxepine‐3‐carbonitriles ( 4 ). Reaction of 3 with aryl methyl ketone ( 5 ) in DMSO at room temperature using powdered KOH as a base produced stair‐shaped 5‐aryl‐7,8‐dihydro‐1,4‐dioxa‐2,3‐dioxodinaphtho[1,2‐b,d]oxepine ( 6 ) in good yields. However, reaction of 6‐aryl‐2H‐pyran‐2‐one‐3‐carbonitrile ( 8 ) with 3,4‐dihydronaphtho[1,2‐b]oxepin‐5(2H)‐one ( 1 ) did not give similar product, but in lieu 4‐aryl‐5,6‐dihydronaphtho[1,2‐b]oxepino[4,5‐b]pyran‐2‐ylidene)acetonitrile ( 9 ) was isolated and characterized.     

Reactions of 3‐benzylindole‐2‐carbohydrazides: Synthesis of new 10‐Benzyl‐1,2‐dihydro‐1‐oxo‐1,2,4‐triazino[4,5‐a]indoles and 3‐Benzyl‐2‐(1,3,4‐oxadiazol‐2‐yl)indoles

3‐Benzylindole‐2‐carbohydrazides (4) on reaction with triethylorthoformate in a polar solvent like DMF yielded only 10‐benzyl‐1,2‐dihydro‐1‐oxo‐1,2,4‐triazino[4,5‐a]indoles (5) while (4) on reaction with triethylorthoacetate in DMF yielded both 10‐benzyl‐4‐methyl‐1,2‐dihydro‐1‐oxo‐1,2,4‐triazino[4,5‐a]indoles (5) and 3‐benzyl‐2‐(5‐methyl‐1,3,4‐oxadiazol‐2‐yl)indoles (6) instead of only the triazinoindoles as expected. The oxadiazolylindoles (6) were also synthesized by refluxing (4) with excess of orthoesters. The structures of the compounds formed were characterized by their analytical and spectral data.     

A facile synthesis of 3‐Substituted 5‐Oxo‐1,2,4‐thiadiazoles from amidoximes

The reaction of amidoximes 1 with 1,1′‐thiocarbonyldiimidazole (TCDI) followed by treatment with silica gel or boron trifluoride diethyl etherate (BF₃·OEt₂) provided 3‐substituted 4,5‐dihydro‐5‐oxo‐1,2,4‐thiadiazoles 2 in moderate yields. The Lewis acids are considered to promote the rearrangement of the thioxocarbamate intermediates 5 to the thiol carbarn ate intermediates 7 , which cyclize to afford 4,5‐dihydro‐5‐oxo‐1,2,4‐thiadiazoles 2 .     

Synthesis,structure, and antibacterial evaluation of new N‐substituted‐3‐amino‐ 5‐oxo‐4‐phenyl‐2,5‐dihydro‐1H‐pyrazole‐1‐carbothioamides

Novel N‐substituted‐3‐amino‐5‐oxo‐4‐phenyl‐2,5‐dihydro‐1H‐pyrazole‐1‐carbothioamide derivatives were synthesized by means of two methods. First is the cyclization reaction of 1‐(cyanophenyl)acetyl‐4‐substituted thiosemicarbazide, and the second one is reaction of cyanophenyl acetic acid hydrazide with isothiocyanate. Structures of new compounds were confirmed by elemental analysis, ¹H NMR, and X‐ray diffraction analysis. Biological evaluation showed that some of them possess promising antibacterial activities. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:215–221, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20598     

5‐Hydroxyalkyl derivatives of tert‐butyl 2‐oxo‐2,5‐dihydro‐1H‐pyrrole‐1‐carboxylate: diastereoselectivity of the Mukaiyama crossed‐aldol‐type reaction

The title compounds, rac‐(1′R,2R)‐tert‐butyl 2‐(1′‐hydroxyethyl)‐3‐(2‐nitrophenyl)‐5‐oxo‐2,5‐dihydro‐1H‐pyrrole‐1‐carboxylate, C₁₇H₂₀N₂O₆, (I), rac‐(1′S,2R)‐tert‐butyl 2‐[1′‐hydroxy‐3′‐(methoxycarbonyl)propyl]‐3‐(2‐nitrophenyl)‐5‐oxo‐2,5‐dihydro‐1H‐pyrrole‐1‐carboxylate, C₂₀H₂₄N₂O₈, (II), and rac‐(1′S,2R)‐tert‐butyl 2‐(4′‐bromo‐1′‐hydroxybutyl)‐5‐oxo‐2,5‐dihydro‐1H‐pyrrole‐1‐carboxylate, C₁₃H₂₀BrNO₄, (III), are 5‐hydroxyalkyl derivatives of tert‐butyl 2‐oxo‐2,5‐dihydropyrrole‐1‐carboxylate. In all three compounds, the tert‐butoxycarbonyl (Boc) unit is orientated in the same manner with respect to the mean plane through the 2‐oxo‐2,5‐dihydro‐1H‐pyrrole ring. The hydroxyl substituent at one of the newly created chiral centres, which have relative R,R stereochemistry, is trans with respect to the oxo group of the pyrrole ring in (I), synthesized using acetaldehyde. When a larger aldehyde was used, as in compounds (II) and (III), the hydroxyl substituent was found to be cis with respect to the oxo group of the pyrrole ring. Here, the relative stereochemistry of the newly created chiral centres is R,S. In compound (I), O—H...O hydrogen bonding leads to an interesting hexagonal arrangement of symmetry‐related molecules. In (II) and (III), the hydroxyl groups are involved in bifurcated O—H...O hydrogen bonds, and centrosymmetric hydrogen‐bonded dimers are formed. The Mukaiyama crossed‐aldol‐type reaction was successful when using the 2‐nitrophenyl‐substituted hydroxypyrrole, or the unsubstituted hydroxypyrrole, and boron trifluoride diethyl ether as catalyst. The synthetic procedure leads to a syn configuration of the two newly created chiral centres in all three compounds.     

Synthesis of novel pyrido[3′,2′:5,6]thiopyrano[3,2‐b]indol‐5(6H)‐ones and 6H‐pyrido[3′,2′:5,6]thiopyrano[4,3‐b]quinolines,two new heterocyclic ring systems

The synthesis of new pyrido[3′,2′:5,6]thiopyrano[3,2‐b]indol‐5(6H)‐ones was accomplished by the Fischer‐indole cyclization of some 2,3‐dihydro‐3‐phenylhydrazonothiopyrano[2,3‐b]pyridin‐4(4H)‐ones, obtained from the 2,3‐dihydro‐3‐hydroxymethylenethiopyrano[2,3‐b]pyridin‐4(4H)‐one, by the Japp‐Klingemann reaction. 6H‐Pyrido[3′,2′:5,6]thiopyrano[4,3‐b]quinolines were obtained by reaction of 2,3‐dihydrothiopyrano‐[2,3‐b]pyridin‐4(4H)‐ones with o‐aminobenzaldehyde or 5‐substituted isatins. The preparation of some derivatives, functionalized with an alkylamino‐substituted side chain, is also described.     

A convenient one‐pot synthesis of new 3‐(4‐aryl‐5‐oxo‐5,6,7,8‐tetrahydro‐4H‐chromen‐2‐yl)‐2H‐chromen‐2‐ones

Anhydrous zinc bromide catalysed reactions of arylidine‐3‐acetyl coumarins ( 1a‐c ) and 5,6‐benzoanalogs of arylidine 3‐acetyl coumarins ( 4a,4b ) with 1,3‐cyclohexanedione gives ‐(4‐aryl‐5‐oxo‐5,6,7,8‐tetrahydro‐4H‐chromen‐2yl)‐2H‐chromen‐2‐ones ( 3a, 3c ) and 5,6‐benzoanalogs of 3‐(4‐aryl‐5‐oxo‐5,6,7,8‐tetrahydro‐4H‐chromen‐2yl)‐2H‐chromen‐2‐one ( 5a,5b ). Under similar conditions arylidine‐3‐acetylcoumarins ( 1a, 1b,1d, 1e, 1f ) and 5,6‐benzoanalog of arylidine 3‐acetyl coumarin ( 4b ) react with 5,5‐dimethyl‐1,3‐cyclohexanedione (dimedone) yielding 3‐(4‐aryl‐7,7‐dimethyl‐5‐oxo‐5,6,7,8‐tetrahydro‐4H‐chromen‐2‐yl)‐2H‐chromen‐2‐ones ( 3d‐3h ) and the 5,6‐benzoanalog of 3.(4‐aryl‐7,7‐dimethyl‐5‐oxo‐5,6,7,8‐tetrahydro‐4H‐chromen‐2‐yl)‐2H‐chromen‐2‐one ( 5c ).     

Researches on thiazolobenzodiazepines: Behavior of tetrahydro‐1,5‐benzodiazepinethiones with aromatic α‐haloketones

A number of 1‐substituted 4H,5H,6H‐[1,3]thiazolo[3,2‐a][1,5]benzodiazepinium‐11‐bromides and S‐(2‐oxo‐2‐phenyl‐X‐(p)‐ethyl)‐3‐(2‐methyl‐1H‐benzimidazol‐1‐yl) propane (or butane) thioate hydrobromides were obtained by direct reaction of the 5‐acetyl(or formyl, or anilinocarbonyl)‐substituted tetrahydro‐1,5‐benzodiazepine‐2‐thiones with aromatic α‐bromoketones. 2‐[(1‐Acetyl‐2(or 3)‐methyl‐2,3‐dihydro‐1H‐1,5‐benzodiazepin‐4‐yl) sulfanyl]‐1‐phenylethanones as intermediates of the formation of thiazolo [3,2‐a][1,5]benzodiazepine and N‐substituted 2‐methyl‐1H‐benzimidazole derivatives have been synthesized. Semiempirical AM1 calculations of a mechanism and energetic parameters for the heptatomic nucleus rearrangement to benzimidazole ring are presented. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:72–81, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20414