Craig A. Obafemi

“Microwave assisted synthesis and antimicrobial activity of 2-quinoxalinone-3-hydrazone derivatives”

A simple and efficient method has been developed for the synthesis of various 2-quinoxalinone-3-hydrazone derivatives using microwave irradiation technique. The series of 2-quinoxalinone-3-hydrazone derivatives synthesized, were structurally confirmed by analytical and spectral data and evaluated for their antimicrobial activities. The results showed that this skeletal framework exhibited marked potency as antimicrobial agents. The most active antibacterial agent was 3-{2-[1-(6-chloro-2-oxo-2H-chromen-3-yl)ethylidene]hydrazinyl}quinoxalin-2(1H)-one, 7 while 3-[2-(propan-2-ylidene)hydrazinyl]quinoxalin-2(1H)-one, 2 appeared to be the most active antifungal agent.

Synthesis and Antimicrobial Activity of Some 2(1H)-quinoxalinone-6-sulfonyl Derivatives

The synthesis of some quinoxalinesulfonyl derivatives is described. Two of the synthesized derivatives, 2-oxo-1,2-dihydroquinoxaline-6-sulfonyl azide (3a) and 2,3-dioxo-1,2,3,4-tetrahydroquinoxaline-6-sulfonyl azide (3b), were screened in vitro for their growth inhibitory activity against nine strains of Gram-positive and seven strains of Gram-negative bacteria, along with two fungal isolates. The two compounds showed broad spectrum (in vitro) activity against the bacterial strains.

Studies of heterocyclic compounds. X. The synthesis and properties of some organotin(IV)-oxygen and-nitrogen heterocycles

Abstract Some representative six-membered heterocyclic organotin(IV)-nitrogen and -oxygen compounds were prepared by the condensation of dialkyltin oxides with hydroxycarboxylic acids, substituted aminocarboxylic acids and diols and characterized by infrared and mass spectra. The compounds were screened against nine species of bacteria and five species of fungi.

Organotin Compounds. I. The Synthesis of Some Dibutyltin and Dibenzyltin Azides and Sulfonates

Abstract SUMMARY The reactions of dibutyltin dichloride and dibenzyltin dichloride with sodium azide, sodium p-toluenesulfonate and silver trifluoromethanesulfonate have been investigated. The products of these reactions include the expected dialkyltin azides and p-toluenesulfonates. In the reactions involving silver trifluoromethanesulfonate, the dialkyltin dichlorides gave only the 1,1,3,3-tetraalkyl-1,3-bis (trifluoromethanesulfonato)- distannoxanes. Other distannoxanes containing the azide and trifluoromethanesulfonato groups attached to tin were also prepared. The infrared spectra and the conductivity characteristics of these compounds are discussed.

STUDIES IN THE HETEROCYCLIC COMPOUNDS: II. THE MASS SPECTRA OF SOME THIOPHENE-SULFONYL DERIVATIVES

Abstract Mass spectra of five 2-thiophenesulfonyl derivatives are determined and the interpretations given are based on mechanistic analogy and supported in most cases by metastable peaks. There are reports in the literature of the effect of electron-impact on thiophene,1 alkylthiophenes,2 2-acyl, 2-aroyl and nitroaroylthiophenes.3–5 However, there has been no report on the mass spectra of 2-thiophenesulfonyl derivatives. The present paper reports an examination of the mass spectra of five 2-thiophenesulfonyl compounds (1–5), figure 1, in order to assess the similarity between the fragmentation pattern of these compounds and those of other reported arysulfonyl derivatives.

STUDIES IN THE HETEROCYCLIC COMPOUNDS V1. SOME REACTIONS OF 5-CHLORO-2-THIOPHENESULFONYL DERIVATIVES

Abstract The reactions of 5-chloro-2-thiophenesulfonyl chloride are described. Treatment of the sulfonyl chloride with ammonia, hydrazine hydrate, sodium azide, indole and imidazole gave the sulfonamides (5), sulfonohydrazide (4), sulfonyl azide (3), 1-(5-chloro-2-thiophenesulfonyl)indole (27) and 1-(5-chloro-2-thiophenesulfonyl)-imidazole (26), respectively. The sulfonyl chloride was reacted further with 20 aryl-and cycloalkyl-amines to give the corresponding sulfonamides (6)-(25). Attempted chlorination of the sulfonyl chloride (2) with sulfuryl chloride or bromination of the sulfonyl azide (3) with pyridinium bromide perbromide failed. However, nitration of the sulfonyl chloride (2) with fuming nitric acid gave the 4-nitro-sulfonyl chloride (28), which with sodium azide afforded the 5-chloro-4-nitro-sulfonyl azide (29). The sulfonyl azides, (3) and (29), have been reacted with triphenylphosphine, triethylphosphite, norbornene and cyclohexene. The azides reacted further with indole and 1-methylindole to...

STUDIES IN THE HETEROCYCLIC COMPOUNDS: I. SOME 2-THIOPHENESULFONYL DERIVATIVES

Abstract 2-Thiophenesulfonyl chloride, prepared by treating thiophene with chlorosulfonic acid, has been condensed with nucleophilic reagents: ammonia, cyclohexylamine, N-methylaniline and sodium azide to afford the sulfonamide. N-cyclohexyl sulfonamide. N.N-methylphenyl sulfonamide and the sulfonyl azide respectively. The sulfonyl azide has been reacted with triphenylphosphine, tri-n-butylphosphine, norbonene and cyclohexene. The ir and nmr spectral characteristics of the products are very briefly discussed.

Synthesis and antibacterial activity of two spiro [indole] thiadiazole derivatives

Isatin reacts with thiosemicarbazide in 50% aqueous alcohol under reflux to give isatin-3-thiosemicarbazone (1′). Compound 1′ cyclizes on treatment with acetic anhydride and pyridine to yield 1,3′-diacetyl-5′-acetamido-3(1H)-spiro[indole-3,2′-[1,3,4]-thiadiazol]-2(1H)-one, 2′. Subsequent reaction of the diacetyl spiro compound, 2′, with hydrazine hydrate at room temperature furnished a white product, which was characterized by spectroscopic means to be 1,3′-diacetyl-5′-amino-3(1H)-spiro[indole-3,2′-[1,3,4]-thiadiazol]-2(1H)-one, 3′. All three compounds (1′, 2′, 3′) were tested for antibacterial activity against six Gram-positive and four Gram-negative bacteria. 1′ showed activity against five Gram-positive and one Gram-negative bacterial strains, while 2′ showed activity against three Gram-positive and two Gram-negative bacterial strains. Compound 3′ showed activity against four Gram-positive and three Gram-negative bacterial strains (better activity than streptomycin, the reference standard).

Synthesis and Some Reactions of 3-Chloro-2-(cyanomethylene)-1,2-dihydroquinoxalines

2,3-Dichloroquinoxaline and some of its derivatives have been reacted with malononitrile and ethyl cyanoacetate to yield a variety of 3-chloro-2-(cyanomethylene)- 1,2-dihydroquinoxaline derivatives. The reaction of 3-chloro-2-(dicyanomethylene)-1,2- dihydroquinoxaline (2e) with pyridine and its methyl derivatives led to the zwitterionic structures 6a-6c. The structures of the newly synthesized compounds were assigned by spectroscopic data and elemental analyses.

Studies on Phosphorus Compounds. I. Synthesis of Chlorosulphonylimino(triphenoxy)-, (Triethoxy)- and (Tris-2-chloroethoxy)phosphoranes

Abstract Reactions of triphenylphosphite, triethylphosphite and tris-2-chloroethylphosphite with chlorosulphonyl azide in acetonitrile-benzene (1:1, v/v) have produced chlorosulphonylimino(triphenoxy)-, (triethoxy)- and (tris-2-chloroethoxy)phosphorane, respectively, in good yields. Similar reaction involving triphenylphosphine gave triphenylphosphine oxide as major product