Mohamed A. Ameen

Heterocyclization of Orthoaminoester and Orthoamino-nitrile-thieno[2, 3-c]pyridine: The Facile Synthesis of Fused Pyridothienopyrimidines

A highly efficient and versatile synthetic approach to the synthesis of pyrido[4′, 3′: 4]thieno[2,3-d]pyrimidines (4, 14, 15, 21) and their heterofused (e.g., triazolo-, triazino-, imidazo-, and tetrazolo-,) pyridothienopyrimidines (5–9, 16, 17, 22–24) is described utilizing 2-amino-3-cyano-4,5,6,7-tetrahydro-thieno[2,3-c]pyridine-6-carboxylic acid ethyl ester ( 2 ) and diethyl 2-isothio-cyanate-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3,6-dicarboxylate ( 10 ) as starting materials.

Synthesis of 1,2,4-triazepine and 1,2,5-triazocine derivatives from the reaction of 2-aminobenzohydrazide with π-acceptors

The formation of metal complexes with acid hydrazides plays an important role in the growth of their biological activity. A simple synthetic strategy is described for the synthesis of novel 1,2,4-tri-azepine and 1,2,5-triazocine derivatives via electron donor–acceptor interaction. Thus when 2-aminobenzohydrazide reacted with tetracyanoethylene (TCNE) and 2-dicyanomethylene-indan-1,3-dione (CNIND) afforded 1,2,4-triazepine derivatives. While on reacting 1 with 2,3-dicyano-5,6-dichloro-1,4-benzoquinone (DDQ), 2,3-dichloro-1,4-naphthoquinone (DCHNQ), 1,4-naphthoquinone and/or 2,3,5,6-tetrabromo-1,4-benzoquinone, 1,2,5-triazocine derivatives were formed.

Designing new scaffolds consisting of hepta-annulated heterocycles

The syntheses of hexa and tetra-propargylated pyrido[4′,3′:4,5]thieno[2,3-d]-pyrido[4″’,3″’:4″,5″]thieno[2″,3″:4′,5′] pyrimido[1′,2′:4,5]pyrazino[1,2-a]pyrimidines, are described by the reaction of hepta-annulated heterocyclic systems with propargyl bromide. Multiple alkyne-azide click reaction of these alkyne cores established them as a scaffold for six and four functionalised 1,2,3-triazoles and attached biomolecules.

A new route for the synthesis of pyrimido[2,1-b][1,3]thiazine ring system

A simple and efficient pathway to conjugate monosaccharides to thienopyrimidines via click chemistry establishing a 1,2,3-triazole linker was reported. Potential pharmaceutical interest is envisaged for the expected target products. Starting from a 2-isothiocyanate-thiophene-3-carboxylate, an allylthiourea was obtained with allylamine, cyclized and S-propargylated to give a thienopyrimidine–alkyne core. Click reaction with tetraacetyl-1-azidoglucose was successful to give the target conjugate with one sugar unit. When propargylamine was used in the first step, the expected thiourea cyclized via the alkyne moiety leading to pyrimido[2,1-b][1,3]thiazine. GRAPHICAL ABSTRACT

A Straightforward and Mild Method of Tethering Monosaccharides to Thieno(2,3-d)pyrimidinones via the Copper(I)-catalyzed Azide-Alkyne 'Click Chemistry'

A mild and versatile method based on Cu(I)-catalyzed [3+2] cycloaddition (Meldal-Sharpless reaction) was developed to tether biomolecules, such as monosacharides or lipophylic azides, to alkyne functions of spirobenzo[b]thieno[2,3-d]pyrimidine-1´-cyclohexane. The reactions are highlighted by their modularity and high efficiency with excellent yields in most cases. The products are interesting precursors for a variety of applications. Graphical Abstract A Straightforward and Mild Method of Tethering Monosaccharides to Thieno[2,3-d]pyrimidinones via the Copper(I)-catalyzed Azide-Alkyne ‘Click Chemistry’

5-Aminouracil as a Building Block in Heterocyclic Synthesis, Part II. One-pot Synthesis of Pyrido[3,2-d:6,5-dʹ]dipyrimidines under Microwave Irradiation without Catalyst

An efficient and direct procedure for the synthesis of pyrido[3,2-d:6,5-dʹ]dipyrimidine derivatives under microwave-assisted conditions is been described. The structures of the products were characterized by elemental analyses, and their IR, 1H NMR, 13C NMR, and MS spectra. Graphical Abstract 5-Aminouracil as a Building Block in Heterocyclic Synthesis, Part II. One-pot Synthesis of Pyrido[3,2-d:6,5-dʹ]dipyrimidines under Microwave Irradiation without Catalyst

Novel selective 5-HT3 receptor ligands : Facile generation methods for 2-amino- and 4-aminopyrido[4',3':4,5]thieno[2,3-d]pyrimidines

This work reports on the synthesis of new 2-amino- and 4-aminopyridothienopyrimidines, with a view to identify potent and selective ligands for the 5-HT3 receptor, starting from derivatives of 2-aminothiophene-3-carboxylic ester, -3-carboxamide, or 2-amino-3-cyanothiophene.

A Novel Synthetic Routes to New 3-Substituted4-oxo-3,4,5,6,7,8-hexahydropyrido[ [4] , [4] , [5] ] thieno[ [2] , [3] ]pyrimidine-7-carboxylic Acid Ethyl Ester Derivatives

Abstract Orthoaminoester 1 was investigated by the reaction with ethylchloroformate, 5-phenyl-oxadiazol-2-thione and triethylorthoformate to afford the open structures, 2 , 13 and 15 . These compounds were subjected to ensuing cyclization in one step or more yielding 3-substituted-5,6-dihydro-8H-4-oxopyrido[ [4] , [4] , [5] ]thieno[ [2] , [3] ]pyrimidine-7(6H)-carboxylic acid ethyl ester derivatives.

Synthesis and evaluation of anticancer and PDE 5 inhibitory activity of spiro-substituted quinazolin-4-ones

A series of novel spiro-substituted 2,3-dihydroquinazolin-4(1H)-ones was synthesized and structurally confirmed by spectral analysis, screened for their anticancer activity at a concentration of 10 μΜ against a panel of 56 cell lines derived from nine different types of cancers, including leukemia, melanoma, lung, colon, CNS, ovarian, renal, prostate, and breast cancers. The synthesized compounds screened for their PDE 5 inhibitory activity and it showed encouraged activity compared to sildenafil.Graphical abstract

Facile Synthesis of Thiazole, Thiazine and Isoindole Derivatives via EDA Approach and Conventional Methods

The reactivity of N-amidinothiourea (1) as an electron donor towards several electron-accepting functional groups via electron-donor-acceptor (EDA) interaction has been studied. Thus on treatment of 1 with either 1,1,2,2-tetracyanoethylene (TCNE, 2), 2,3-dicyano-1,4-naphthoquinone (DCNQ, 4), 2,3,5,6-tetrabromo-1,4-benzoquinone (BHL-p, 6), 2,3-dichloro-1,4-naphthoquinone (DCHNQ, 8), 2,3,5,6-tetrachloro-1,4-benzoquinone (CHL-p, 13), 2,3-dicyano-5,6-dichloro-1,4- benzoquinone (DDQ, 15), 2-dicyanomethyleneindan-1,3-dione (CNIND, 17), 2-(2-oxoindolin-3- ylidene)malononitrile (19), and/or dimethyl acetylenedicarboxylate (DMAD, 21), the reaction proceeds to give thiazole and thiazine derivatives, respectively. However, isoindole derivatives 24 and 26 were formed on heating of 1 with either tetrabromophthalic anhydride and=or o-phthalaldehyde, respectively. The products were fully characterized according to their spectral data. The mechanisms of formation of the products have been rationalized. Graphical Abstract Facile Synthesis of Thiazole, Thiazine and Isoindole Derivatives via EDA Approach and Conventional Methods