Mahmoud Al-Talib

The reaction of 2-azaallenium salts with carbodiimides and tert-butyl isocyanide

Abstract 2-Azaallenium salts 1 react with diisopropyl carbodiimide to afford the formal dihydro-1,3-diazetium salts 5 . The structure of 5c has been confirmed by an X-ray diffraction analysis. With the carbodiimide 2e the tetraphenyl-2-azaallenium salt 1a reacts to give the guanidinium compound 6 .The diazetium salts 5 react with further carbodiimide to afford the formal 2-azaallenium salts 11 . With tert-butyl isocyanide the 2-azaallenium salts 1 undergo an Ugi reaction to yield the nitriles 14 .

The reaction of acylium salts with dialkylcyanamides

Abstract Aliphatic and aromatic acid chlorides react with dialkylcyanamides in the presence of Lewis acid at low temperature. The reaction proceeds via a stepwise mechanism to afford 1,3,5-oxadiazinium salt in good yields.

Dual behavior of monothiocarbohydrazones in the cyclization with diethyl acetylene dicarboxylate (DEAD): synthesis of substituted 1,3-thiazolidin-4-ones

Condensed 4-thiazolidinones have attracted the attention of organic chemists and pharmacologists due to the biological significance associated with the thiazolidinone nucleus. On the other hand, the synthesis of spiro compounds has always been a challenge and attraction due to their pharmacological activities. 4-Thiazolidinones are embedded in the structures of various synthetic pharmaceuticals displaying a broad spectrum of biological activities (1), including antimicrobial (2), antifungal (3), antimalarial (4), antiviral (5), antibacterial (5), antioxidant (6), anti-HIV (7),

1H and 13C NMR Spectroscopy of Substituted Tris‐1,3,4‐oxadiazoles

1,3,5‐Tris(5‐substituted‐1,3,4‐oxadiazol‐2‐yl)benzenes were prepared by the dehydration of the corresponding hydrazides. The structures of these compounds were elucidated by IR, 1H and 13C NMR spectroscopy.

On the Reaction of α,α-Dichlorocarbenium Ions with Isocyanates

Trichlormethanes 4 react with two equivalents of n-alkyl isocyanates R2-NCO in the presence of SbCl5 to furnish the 2,2-dichloro-5,6-dihydro-6-oxo2H-1,3,5-oxadiazinium salts (9). The structure of these heterocycles is confirmed by an X-ray analysis of 9d (R1 = ClC = CCl2, R2 = Et). p-Tolyl isocyanate is Friedel-Crafts alkylated by 4b in the presence of SbCl5. Subsequent ring closure affords the quinolinium salt 13, which is hydrolyzed to give inter alia the quinolone 16.

Effect of Ethanol and Acetonitrile Containing Some Aryl-Substituted Bis-1,3,5-Oxadiazinium Salts on the Corrosion of Aluminum

Abstract The chemical and electrochemical behavior of aluminum has been studied in ethanol— and acetonitrile—water mixtures at 15°C using the weight-loss method and the potentiostatic polarization technique. Also, the effect of some aryl-substituted bis-1,3,5-oxadiazinium salts on the corrosion of aluminum in acetonitrile was studied. Acetonitrile and ethanol act as interface inhibitors, whereas oxadiazinium salts with hexachloroantimonate counter anions were found to stimulate the dissolution of aluminum. The effects of the substituent of the aromatic moiety of the oxadiazinium salts and the counter anions on the corrosion of aluminum have also been studied.

1,1-Diaminosubstituted 2-azaallenium salts: preparation and barriers to topomerization

Abstract Dialkylcarbodiimides, 5 , react with iminium salts, 6 , to afford the formal 1,1-diaminosubstituted 2-azaallenium salts 3 . According to dynamic NMR measurements compounds 3 must be regarded as alkylidene-guanidinium salts A , undergoing a fast topomerization via a transition state B with allene geometry (†G= 265 = 45.9 ± 1 kJmol-1 for 3f ) and a slower rotation around the peripheral C-N bonds (transition state C ; †G= 290 = 58.0 ± 1 kJmol-1 for 3f ).

Unusual product from the acid-catalyzed one-pot, multicomponent reaction of thiocarbohydrazide, aldehydes, and phenacyl bromides

ABSTRACT A one-pot, three-component protocol for the synthesis of novel five-membered thiazole ring bonded to two hydrazone motifs is described. The acid-catalyzed reaction of one equivalent of thiocarbohydrazide, two equivalents of aromatic aldehydes, and one equivalent of phenacyl bromides afforded the five-membered thiazole ring. The reactions proceed with novel chemoselectivity. Similar reported protocols have always afforded 1,3,4-thiadiazines. GRAPHICAL ABSTRACT

On the Reaction of alpha,alpha-Dichlorocarbenium Ions with Isocyanates

Trichlormethanes 4 react with two equivalents of n-alkyl isocyanates R2-NCO in the presence of SbCl5 to furnish the 2,2-dichloro-5,6-dihydro-6-oxo2H-1,3,5-oxadiazinium salts (9). The structure of these heterocycles is confirmed by an X-ray analysis of 9d (R1 = ClC = CCl2, R2 = Et). p-Tolyl isocyanate is Friedel-Crafts alkylated by 4b in the presence of SbCl5. Subsequent ring closure affords the quinolinium salt 13, which is hydrolyzed to give inter alia the quinolone 16.

On the Reaction of ?,?-Dichlorocarbenium Ions with Isocyanates

Trichlormethanes 4 react with two equivalents of n-alkyl isocyanates R2-NCO in the presence of SbCl5 to furnish the 2,2-dichloro-5,6-dihydro-6-oxo2H-1,3,5-oxadiazinium salts (9). The structure of these heterocycles is confirmed by an X-ray analysis of 9d (R1 = ClC = CCl2, R2 = Et). p-Tolyl isocyanate is Friedel-Crafts alkylated by 4b in the presence of SbCl5. Subsequent ring closure affords the quinolinium salt 13, which is hydrolyzed to give inter alia the quinolone 16.