An interesting cyclization of N‐methyl‐3‐phenyl‐N‐(2‐(Z)‐phenylethenyl)‐cis‐oxiranecarboxamide

Under Lewis acid condition, N‐methyl‐3‐phenyl‐N‐(2‐(Z)‐phenylethenyl)‐cis‐oxiranecarboxamide undergoes elegant double cyclizations to give interesting products.     

New synthetic route towards 2,2‐dimethylchromene and synthesis of substituted 7‐(dimethylpropargyl)chromene

Trifluoromethansufonic acid (TFA) was found a proper reagent for regioselectively ring closure of resorcinol to afford 7‐hydroxy‐2,2‐dimethyl‐2,3‐dihydrochromen‐4‐one 3 . The propargylation of 3 gave rise to 2,2‐dimethyl‐7‐(2‐methylbut‐3‐yn‐2‐yloxy)‐2,3‐dihydrochromen‐4‐one 4 . Condensation of 4 with substituted phenyl or benzyl Grignard reagents afforded substituted phenyl or benzylidene chromenes 6a‐d and 4‐(substitutedbenzylidene)‐3,4‐dihydro chromenes 8a‐e , respectively.     

Facile three‐component one‐pot synthesis of indeno‐[1,2‐b]quinolin‐9,11(6H,10H)‐dione derivatives

One‐pot three‐component cyclocondensation of aldehydes, 1,3‐indanedione and enaminones proceeds in the presence of acetic acid to afford Indeno[1,2‐b]quinolin‐9,11(6H,10H)‐dione derivatives, The method has the advantage of excellent yields(85‐94%) and simple workup procedure.     

Facile coupling of 2‐(1‐ethylthioethenyl)pyrroles with amines: A route to 2‐(1‐aminoethenyl)pyrroles and 1‐amino‐3‐iminopyrrolizines

2‐(2‐Cyano‐1‐ethylthioethenyl)pyrroles are readily coupled (50–55°) with primary and secondary amines at the position 1 of the ethenyl moiety to eliminate ethanethiol and afford 2‐(1‐amino‐2‐cyanoethenyl)pyrroles and/or their cyclic isomers ‐ functionalized 1‐amino‐3‐iminopyrrolizines in good to high yields.     

Reactions of aroylthioureas with acetylenic esters and dibenzoyl ethylene. Selectivity towards the formation of new 1,3‐thiazines

A series of 1,3‐thiazines has been synthesized by the reactions of N‐aroylsubstituted thioureas with ethyl propiolate, dimethyl but‐2‐ynedioate and (E)‐1,4‐diphenyl‐but‐2‐ene‐1,4‐dione. The reaction of antipyrinylphenyl thiourea with π‐deficient acetylenic reagents did not afford the corresponding 1,3‐thiazines, whereas pyrrolo‐pyrazolopyrimidines were obtained.     

Reactions of some pyrrole‐2,3‐diones with hydrazine hydrate and o‐phenylenediamine

2,3‐Dihydro‐1H‐pyrrole‐2,3‐diones 1a‐d react with hydrazine hydrate 2 and o‐phenylenediamine 4 under different conditions to yield the pyrazole‐3‐carboxamide derivatives 3a‐d , the pyrrol‐2‐ones 5a‐d and the quinoxaline‐2‐one derivatives 6a‐d , respectively. Hydrolysis of the quinoxaline‐2‐one derivatives 6a‐d gave a substituted furo[2,3‐b]quinoxaline 7 . The structures of the synthesized compounds were assigned on the basis of analytical results as well as spectroscopic data.     

Microwave assisted synthesis of thiazolo[3,2‐b][1,2,4]‐triazoles containing 1,8‐naphthyridine moiety

A simple and efficient protocol for the synthesis of 5‐aryl‐2‐(2‐substituted‐1,8‐naphthyridin‐3‐yl)‐thiazolo[3,2‐b][1,2,4]triazoles ( 4 ) is achieved by cyclocondensation of 3‐(2‐substituted‐1,8‐naphthyridin‐3‐yl)‐1,2,4‐triazoles ( 3 ) with α‐halogenoketones in anhyd. methanol under microwave irradiation. The products are obtained in good yields and in a state of high purity.     

Synthesis of some novel 2,6‐disubstituted pyridazin‐3‐ones as TMC120 analogues

Different analogues of TMC120 derived from pyridazin‐3(2H)‐one rings were synthesized by coupling of 3,6‐dichloropyridazine with arylacetonitriles, phenols and/or aniline derivative followed by hydrolysis and alkylation with different benzyl bromide derivatives.     

The reaction of 2‐aroyl‐3,3‐bis(alkylsulfanyl)acrylaldehydes and hydroxylamine hydrochloride: Facile synthesis of differently substituted isoxazoles

2‐Aroyl‐3,3‐bis(alkylsulfanyl)acrylaldehyde was utilized for the synthesis of three different isoxazoles by reacting with hydroxylaminehydrochloride. We synthesized differently substituted isoxazoles like (aryl)[5‐(methylsulfanyl)‐4‐isoxazolyl]methanones, 3‐(methylsulfanyl)‐5‐phenyl‐4‐isoxazolecarbonitriles and 5‐aryl‐3‐(methylsulfanyl)‐4‐isoxazolecarbaldehyde oximes in good yields by varying the substratereagent stoichiometry and temperature of the reaction medium.     

Reaction of 3‐formylchromone‐N‐benzoylhydrazone with ketenes. Synthesis and structural studies of chromone 1,3,4‐oxadiazolines

The reaction of 3‐formylchromone‐N‐benzoylhydrazone with ketenes, prepared in situ from the corresponding acid chlorides 2a‐d and the mixed anhydride 2e was studied. In all cases 2‐(4′‐oxo‐4′H‐3′‐chromyl)‐5‐phenyl‐2,3‐dihydro‐1,3,4‐oxadiazoles ( 3 ) were isolated in yields varying from 40 to 80%. A full structure assignment of all products has been made on the basis of 1D and 2‐D (COSY H‐H, COSY C‐H, COLOC C‐H) NMR spectra. A plausible reaction mechanism is also proposed based on theoretical approaches and experimental results.     

Stereoselective SE2′ Protonation of α‐Hydroxyallylsilanes Mediated by a Brook Rearrangement

Brooked up! Treatment of (R,Z)‐3‐(tert‐butyldimethylsilyl)‐1‐cyano‐3‐hydroxyprop‐1‐enyl carbamate with a catalytic amount of a base afforded (S,E)‐3‐(tert‐butyldimethylsilyloxy)‐1‐cyanoallyl diisopropylcarbamate, showing that S_E2′‐type reaction of allylsilicates proceeds in an anti fashion. The overall process is equivalent to trapping of an enantioenriched C‐chiral carbanion at the α‐position of nitrile group in up to 77 % ee (see scheme).

     

Microwave assisted synthesis of coumarins via potassium carbonate catalyzed knoevenagel condensation in 1‐n‐butyl‐3‐methylimidazolium bromide ionic liquid

A variety of substituted coumarins have been prepared via an inexpensive and efficient potassium carbonate catalyzed Knoevenagel condensation of salisylaldehydes with acidic methylene compounds in ionic liquid media. 1‐n‐Butyl‐3‐methylimidazolium bromide has been employed as an alternative reaction medium in this procedure. The reaction proceeds smoothly under mild and solvent‐free conditions and the products are obtained in excellent yields. Mild reaction conditions and good to excellent yields of the products are the noteworthy advantages of the method.     

6‐Nitro‐1,2,3,4‐tetrahydroquinolines by a tandem reductive amination‐SNAr reaction

A tandem reductive amination‐S_NAr reaction has been developed for the synthesis of 6‐nitro‐1,2,3,4‐tetrahydroquinolines. Treatment of 4‐(2‐fluoro‐5‐nitrophenyl)‐2‐butanone or 3‐(2‐fluoro‐5‐nitrophenyl)‐propanal with primary amines and sodium cyanoborohydride in methanol at room temperature provided good to excellent yields of the substituted tetrahydroquinolines. The reaction proceeded best with the ketone substrate using primary amines that were unbranched at the α‐carbon. The aldehyde also produced the target heterocycles, but these were accompanied by 10‐15% of the uncyclized side chain reductive amination products.     

Synthesis of 5,6,7,8‐tetrahydroindolizines via a domino‐type transformation based on the rhodium catalyzed hydroformylation of N‐(β‐methallyl)pyrroles

Variously substituted 5,6,7,8‐tetrahydroindolizines can be easily synthesized via a domino reactions sequence under rhodium catalyzed hydroformylation of N‐(β‐methallyl)pyrroles. The later are readily prepared from properly functionalized pyrroles via phase‐transfer N‐allylation in the presence of 18‐crown‐6 and potassium tert‐butoxide.     

Quinolone analogues 9. Synthesis of 7‐methylsulfanyl‐ and 7‐methanesulfonylpyridazino[3,4‐b]quinoxalin‐4(1H)‐ones

The reaction of 7‐chloro‐1‐methylpyridazino[3,4‐b]quinoxalin‐4(1H)‐ones 3a‐5a with sodium methylthiolate gave 1‐methyl‐7‐methylsulfanylpyridazino[3,4‐b]quinoxalin‐4(1H)‐ones 8a‐c , whose reaction with m‐chloroperbenzoic acid afforded the 7‐methanesulfonyl‐1‐methylpyridazino[3,4‐b]‐quinoxalin‐4(1H)‐ones 9a‐c , respectively. The above substituent change at the 7‐position resulted in the activity alteration to microorganisms.