Maher F. El-Zohry

Nonconventional Friedel-Crafts chemistry. III: On the regiospecific synthesis of spiro[cycloalkane-1,1'-isothiochroman]-4'-one derivatives

Abstract The reaction of 1-oxa-4-thiaspiro[4,4]nonan-2-one (4) and/or 1-oxa-4-thiaspiro[4,5]decan-2-one (5) with arenes (6) under the catalytic action of aluminum chloride afforded in all cases spiro[cycloalkane-1,1′-isothiochroman]-4′-ones (7a-g and 8a-g), [(arylcycloalkyl)thio]-acetic acid, (9a-g and 10a-g), cy-cloalkylthioacetic acids, (11 and 20) aryl cycloalkyl sulfides, (14 and 23) diaryl sulfides (15), diaryl disulfides and dicycloalkyl disulfides (13 and 22). The mechanisms of these reactions are discussed.

Modern Friedel-Crafts chemistry. XI: Cyclization of aryl haloalkyl sulfones, arylsulfonylacyl chlorides and their corresponding sulfides

Abstract The sulfone group deactivation for cyclialkylation and cycliacylation reactions in the presence of Friedel-Crafts catalysts was demonstrated in a number of aryl chlorlalkylsulfones (1–8) and arylsulfonylacyl chlorides (17a-22a), respectively. As expected, the corresponding arylchloralkyl sulfides (9–16) and arylmercaptoacyl chlorides (13a-28a) underwent ring-closure reaction in most cases under the same conditions. The ease of cyclization was governed by the ring size, the stability of the attacking carbocation and the nucleophilicity of the aryl moiety. Also the behaviour of benzyl sulfones (29, 31a, and 32a) and sulfides (33, and 36a) was inconsistent. Noteworthy, the Friedel-Crafts cyclization reaction is thus considered an accessible method for the synthesis of compound 37–41 and 45,51.

NONCONVENTIONAL FRIEDEL-CRAFTS CHEMISTRY II. ON THE CATALYTIC ACTION OF TRIFLIC ACID AND ALUMINIUM CHLORIDE ON SELECTED ARYL THIOESTERS

Abstract The catalytic action of triflic acid and/or aluminium chloride on seven selected aryl thioesters (1-7) gave in all cases aryl thiols, diaryl sulfides, diaryl disulfide, and thianthrene derivatives in addition to the corresponding aryl carboxylic acids. Thioester 5 gave thiochromanone derivatives in good yield under the same conditions. Plausible mechanisms were suggested to rationalize the obtained results.

MOLECULAR REARRANGEMENTS. VI. THERMOLYSIS OF α-(N-ARYL)BENZYL ARYL SULFIDES

Abstract In view of the significance of studying the effect of heat on organic compounds especially those containing nitrogen and/or sulfur, six substituted α-(N-aryl) benzyl aryl sulfides (4–9) were prepared and subjected to thermolysis at 200°C. Surveying of the reaction products showed the formation of amines, benzylidene amines, sulfides, disulfides, dibenzyl, stilbene, benzthiazole, benzimidazole, tetraphenyl thiophene as principle products in variable ratios according to the type of the starting sulfide. A mechanism involving the homolytic cleavage of the C[sbnd]S and the C[sbnd]N bond is suggested to rationalize the thermolysis products.

Synthesis and Reactions of Some New Spiropyranthiazoline Derivatives

Pyrano[2,3-d]thiazoline-7-spiro-3′-(1′-substitutedindoline-2′-ones) 5a,b has been synthesized and reacted with some nucleophile reagents to afford new spirothiazolino[4,5:2′,3′]pyrano[6′,5′-d]pyrimidine derivatives 6a,b–13a,b, which are analogues of some reported biologically active spiroheterocyclic compounds.

CYCLIZATION OF SELECTED BENZYL SULFONE DERIVATIVES UNDER PHASE TRANSFER CATALYTIC CONDITIONS

Abstract Seven selected benzyl chloroalkyl sulfones(1a-c) and benzyl carboethoxyalkyl sulfones (1d-q) has been subjected to treatment with aqueous NaOH (50%) under PTC conditions. Analysis of the product mixtures revealed competitive cyclization, elimination and hydrolysis reactions. Correlation of the reaction products and the starting sulfone has been discussed.

MODERN FRIEDEL-CRAFTS CHEMISTRY XVI. REACTION OF THIOPHENE WITH BIFUNCTIONAL MOLECULES UNDER DIFFERENT FRIEDEL-CRAFTS CATALYSTS: ATTEMPTED SYNTHESIS OF CYCLOPENTA[b] THIOPHENES AND DIHYDROBENZO[b] THIOPHENES

Abstract The reaction of thiophene (1) with 3-chloropropionyl chloride (2), 4-chlorobutyryl chloride (3), crotonyl chloride (4) and cinnamoyl chloride (5) under different Friedel-Crafts catalysts (A1C13/CH3NO2, FeCl3, and A1C13/CS2) was investigated. The cyclic products 4,5-dihydro-6H-4-methylcyclo-pental[b]-thiophen-6-one, 5,6-dihydrobenzo[b]thiophen-7(4H) one and 4-phenyl-6H-cyclopenta[b]thio-phen-6-one were formed. The different behaviors of compounds (2–5) towards thiophene were discussed.

SYNTHESIS OF SOME NEW FUSED SPIROHETEROCYCLIC SYSTEMS RELATED TO THIAZOLOPYRANS, THIAZOLOTHIOPYRANS AND THIAZOLOPYRIDINES

Abstract 1-Oxa-4-thiaspiro[4.4]nonan-2-one and/or 1-oxa-4-thiaspiro[4.5]decan-2-one were reacted with aniline to give the corresponding spirothiazolidinones(1a, b). Reaction of 1a, b with chalcones yielded 2-(α-aracylbenzyl)-4-phenyl-1-thia-4-azaspiro[4.4]nonan-3-one and 2-(α-aracylbenzyl)-4-phenyl-1-thia-4-azaspiro[4.5]decan-4-one (2a–h). Compounds 2a–h were reacted with acetic anhydride, phosphorus pentasulfide and ammonium acetate to give spirothiazolopyrans 3a–h, spirothiazolothiopyrans 4a–h and spirothiazolodihyropyridines 5a–h respectively. All the synthesized spiroheterocycles derivatives were identified by conventional methods (IR, 1H-NMR) and elemental analyses.

NONCONVENTIONAL FRIEDEL-CRAFTS CHEMISTRY IV. ON THE REACTION OF 1,3-OXATHIOLAN-5-ONE-2-SPIRO-1′-CYCLOALKANES WITH FERROCENE IN THE PRESENCE OF AlCl3 CATALYLST

Abstract The reaction of ferrocene with 1-oxa-4-thiaspiro[4,4]nonan-2-one (1) and/or 1-oxa-4-thiaspiro[4,5]-de-can-2-one (2) in the presence of aluminum chloride catalyst afforded the spiroferrocene derivatives 4, 6, 5 and 7, respectively. The mechanism of these reactions is discussed.

Modern Friedel-Crafts chemistry. XIV: On the cyclization of selected aryl hydroxyalkyl sulfides

Abstract The feasibility of cycloalkylation reactions in the presence of Friedel–Crafts catalysts was demonstrated in a number of aryl hydroxyalkyl sulfides (1–5), and benzyl hydroxyalkyl sulfides (6–7). Treatment of compounds (1–7) with Friedel-Crafts catalysts gave diaryl disulfides, diaryl sulfides, arene thiols, chlorohydrins, aryl chloroalkyl sulfides, aryl alkenyl sulfides and cyclization products. It is noteworthy to mention that cyclization products were isolated only in cases where the hydroxyl group is linked to a tertiary carbon atom as in compounds 3 and 7. A suitable reaction pathway is suggested to rationalize the formation of the various reaction products.