Synthesis of novel N‐alkyl/aryl‐N′‐(4‐arylthiazol‐2‐yl)‐N″‐xylosyl guanidines

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     

A new synthesis of N‐alkyl pyrazolidine‐3,5‐diones and tetrahydropyridazine‐3,6‐diones

N‐alkyl pyrazolidine‐3,5‐diones and tetrahydropyridazine‐3,6‐diones have been synthesized by a new method in a three‐step sequence from dialkyl malonates or succinates respectively.     

Synthesis of 2‐alkyl‐4,5‐aryl‐2H‐[1λ6,2,3,6]‐thiatriazine‐1,1‐dioxides

Sulphamoyl chlorides and chlorosulphonyl isocyanate react with monosubstituted hydrazones and alkylhydrazonates to sulphamoyl hydrazones and sulphamoyl hydrazonates respectively. Reaction of benzil monoalkylhydrazones with chlorosulphonyl isocyanate results in formation of 2‐alkyl‐4,5‐aryl‐2H‐ [1λ⁶,2,3,6]‐thiatriazine‐1,1‐dioxides.     

Convenient synthesis of N‐substituted 1‐alkyl and 1‐aryl‐3‐aminoisoquinolines

Cyclocondensation of 2‐acylphenylacetonitriles 1 with amines affords 1‐substituted 3‐aminoisoquinolines 2 in good yields.     

Synthesis of indole‐4‐carboxaldehydes and 4‐acetylindole from N‐alkyl‐5‐aminoisoquinolinium salts

N‐Alkyl‐5‐aminoisoquinolinium salts ( 8a‐d ) are converted into indole‐4‐carboxaldehydes ( 1a‐c ) on heating in a two phase alkyl acetate‐water system containing an excess of a 2:1 sodium bisulfite‐sodium sulfite mixture. 4‐Acetylindole 1e is prepared in the same way from 1‐methyl‐2‐cyanomethylisoquinolinium bromide 8f .     

A New Solution—phase Parallel Synthesis of 2—Alkyamino—3—aryl—5—phenylmethylene—3,5—dihydro—4H—imidazol—4—ones

Thirteen new 2-alkylaminoimidazolones(4) wre rapidly synthesized by a new solution-phase parallel synthetic method,which includes aza-Wittig reaction of iminophosphorane(1) with aromatic isocyanate to give carbodi-imide(2) and subsequent reaction of 2 with various aliphatic primary amine in a parallel fashion.The products were confirmed by ^1H NMR,MS,IR and X-ray crystallographic analysis.The unusual selectivity of the cyclization was probably due to the deometry of the guanidine intermediate.     

Synthesis of New N‐alkyl‐5‐formyl‐2‐methylpyrrole Derivatives from Glucosamine

Glucosamine hydrochloride 1 was treated with 1,3‐dicarbonyl compounds to obtain 2‐methyl‐5‐(1,2,3,4‐tetrahydroxy‐butyl) pyrrole 2a and 2b , respectively. Under the role of NaIO₄, 2a and 2b were successfully transformed into the related 5‐formal pyrrole derivative 3a and 3b , respectively. Compounds 4a – 4d and 5a – 5e were obtained by reacting 3a and 3b with chlorinated hydrocarbons by alkylation reactions, respectively. The structures of all new products were confirmed by IR, NMR, and HRMS spectra.     

An efficient synthesis of a class of novel N‐Alkyl‐N‐aryl‐4‐hydroxy‐1‐methyl‐2‐oxo‐1,2‐dihydro‐3‐quinolinecarbothioamides

The novel title compounds have been prepared in high yield by an optimized amide coupling followed by a Dieckmann cyclization. Additionally, this new route is amenable to preparative scale synthesis.     

Synthesis of 2‐amino‐4,5‐dihydro‐3‐methanesulfonylfurans (and ‐thiophenes)

2‐Amino‐4,5‐dihydro‐3‐methanesulfonylfurans 7 and 2‐amino‐4,5‐dihydro‐3‐methanesulfonylthiophenes 8 were prepared by deamidation of tetrahydro‐2‐imino‐3‐methanesulfonyl‐3‐furancarboxamides 3 and of tetrahydro‐2‐imino‐3‐methanesulfonyl‐3‐thiophenecarboxamides 4 with bases. Compounds 3 and 4 were obtained by reaction of 2‐amino‐4,5‐dihydro‐3‐furancarboxamides 1 and 2‐amino‐4,5‐dihydro‐3‐thio‐phenecarboxamides 2 with methanesulfonyl chloride in the presence of triethylamine.     

Reaction of 3‐aminoquinoline‐2,4‐diones with isocyanates. Synthesis of novel 3‐(3′‐alkyl/arylureido)quinoline‐2,4‐diones and their cyclic carbinolamide isomers

3‐Alkyl/aryl‐3‐amino‐1H,3H‐quinoline‐2,4‐diones react with alkyl/aryl isocyanates to give novel 3‐alkyl/aryl‐3‐ureido‐1H,3H‐quinoline‐2,4‐diones or 3a‐alkyl/aryl‐9b‐hydroxy‐3,3a,5,9b‐tetrahydro‐1H‐imidazo[4,5‐c]quinoline‐2,4‐diones. In some cases, a mixture of both products was obtained and separated by fractional crystallization. All compounds were characterized by their ¹H, ¹³C, ir and ms data and some of them also by ¹⁵N nmr data.     

Intramolecular cyclization of N‐hetarylphosphinimidic isocyanates in the synthesis of 1,7‐dihydro‐4H‐imidazo[4,5‐d][1,3,2]diazaphosphinin‐4‐one (2‐phosphapurine)

It has been found that N‐(4‐imidazolyl)phosphinimidic isocyanates obtained by the reaction of the corresponding chlorophosphine N‐hetarylimide with alkali metal cyanates can undergo intramolecular heterocyclization to yield previously unknown phosphapurine derivatives containing an endocyclic PN double bond. This radically novel approach to building the 2‐phosphapurine system shows promise for the synthesis of related phosphorus‐containing fused heterocycles. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:453–455, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20617     

Synthesis and antioxidant activities of novel N‐aryl (and N‐alkyl) γ‐ and δ‐imino esters and ketimines

Novel N‐aryl (and N‐alkyl) γ‐ and δ‐imino esters 2a–g ( 3a–g ) and N‐aryl (and N‐alkyl) ketimines 2h–j ( 3h–j ) were synthesized in high yields (80–99%) from their corresponding γ‐ and δ‐keto esters and ketones in this study. The structures of the synthesized compounds were clarified by Fourier transform infrared (FT‐IR), NMR (¹H and ¹³C), mass spectrometry, and elemental analyses. Isomerizations [E/Z] were also determined by their ¹H NMR spectra. The free‐radical scavenging activity of imines was evaluated using the 1,1‐diphenyl‐2‐picryl‐hydrazyl (DPPH) method. The relationships between the structure and antioxidant activity of these compounds are discussed. Among these compounds, 2a–c (at the concentration 1000 μg/mL) exhibit high antioxidant activity similar to those of the standards (butylated hydroxyanisole [ BHA], butylated hydroxytoluene [ BHT], and ascorbic acid).     

Reactions of 1‐(3‐aryl‐3‐oxopropenyl)azulenes and 1‐cinnamoylazulenes with malononitrile: Synthesis of 1‐(2‐aryl‐4‐pyridyl)azulenes and 1‐(4‐aryl‐2‐pyridyl)azulenes

The reactions of 1‐formyl‐3‐methoxycarbonylazulene ( 1 ) with acetophenones 3a‐e gave 1‐(3‐aryl‐3‐oxopropenyl)‐3‐methoxycarbonylazulenes 4a‐e which reacted with malononitrile in the presence of sodium methoxide to afford 1‐(2‐aryl‐4‐pyridyl)‐3‐methoxycarbonylazulenes 9a‐d , except for 4′‐nitro‐substituted compounds. Heating of the compounds 9a‐d in 100% phosphoric acid yielded 1‐(2‐aryl‐4‐pyridyl)azulenes 10a‐d . In a similar manner, 1‐(4‐aryl‐2‐pyridyl)azulenes 12a‐1 and 1‐[4‐(2‐furyl)‐ and 4‐(2‐thienyl)‐2‐pyridyl)]azulenes 14a,b were obtained.     

A novel and direct synthetic route to substituted 1,5‐dihydro‐4H‐[1]benzopyrano[4,3‐b]pyridine‐4,5‐diones

The condensation of 4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one and substituted 2‐hydroxybenzaldehydes with ammonium acetate gave the title heterocycles. Synthesis of 1,5‐dihydro‐2‐methyl‐4H‐[1]naphtho‐[1′,2′:5,6]pyrano[4,3‐b]‐pyridine‐4,5‐dione is also described. A reaction mechanism is discussed.     

Synthesis of 6‐Alkylidene‐5,6‐dihydro‐4H‐1,3‐thiazine Derivatives via the Cyclization of N‐3‐Bromo‐3‐alkenylthioamides

By the treatment of N‐3‐bromo‐3‐alkenylthioamides with sodium hydroxide in DMF‐H₂O in the presence of tetra‐butylammonium bromide, series of 6‐alkylidene‐5,6‐dihydro‐4H‐1,3‐thiazine derivatives were prepared in moderate to good yields. The cyclization is supposed to proceed via both the intramolecular vinylic nucleophilic substitution and the elimination‐addition mechanisms (formation of acetylenic intermediates) in a competitive manner.     

Study of direction of cyclization of 1‐azolil‐4‐aryl/alkyl‐thiosemicarbazides

On a four series of 1‐azolil‐4‐aryl/alkyl‐thiosemicabazides, a study on the influence of azole moiety on the capability for intramolecular cyclization and its direction was carried out. It was found that for 4‐aryl/alkyl‐thiosemicabazides with triazole, imidazole, or pyrrole moiety at N‐1 nitrogen atom possible products were only s‐triazoles, both in alkaline and acidic medium. Successful dehydrocyclization of 1‐azolil‐4‐aryl/alkyl‐thiosemicarbazides leading to a thiadiazole has been documented only for a series of 1‐(4‐methyl‐1,2,3‐thiadiazol‐5‐yl‐carbonyl)‐4‐aryl/alkyl‐thiosemicarbazides. It can be speculative that the determination of pK_a value of oxygen atom of 1‐azolil‐4‐aryl/alkyl‐thiosemicarbazide can be a very valuable parameter in the prediction of the possibility of dehydrocyclization to form thiadiazole. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:521–532, 2010; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20643