Nihat Akbulut

CoTPP-catalyzed reaction of saturated bicyclic endoperoxides

Abstract Saturated bicyclic endoperoxides were exposed to CoTPP (Cobalt-meso-tetraphenylporphyrine) in chloroform, the peroxide bond was cleaved and a mixture of products arising from fragmentation and reduction obtained.

Thermolysis and CoTPP-catalyzed rearrangement of endoperoxides derived from 2.3-dihydro-1(2H)azulenone: A new endoperoxide-endoperoxide rearrangement☆

Abstract Thermolysis and CoTPP (cobalt-meso-tetraphenylporphyrine)-catalyzed reactions of endoperoxides (2), (3), and (4) derived from 2.3-dihydro-1(2H)-azulenone have been studied and a new endoperoxide-endoperoxide rearrangementhas been discovered.

Synthesis and Chemistry of Endoperoxides Derived from 3,4-Dihydroazulen-1(2H)-one: An Entry to Cyclopentane-Anellated Tropone Derivatives

Reduction of trienone 1 and subsequent treatment with acid in MeOH furnished 1-methoxy-1,2,3,4-tetrahydroazulene (13). Photo-oxygenation of 13 provided the two bicyclic endoperoxides 14 and 15. Pyrolysis of 14 and 15 gave the corresponding bis-epoxides 17 and 18, which have been synthesized also upon treatment with a catalytic amount of CoTPP (TPP=tetraphenylporphyrin). That an unusual endoperoxide-endoperoxide rearrangement has not been observed strongly supports the assumption that the carbonyl group in 2 – 4 is responsible for this unprecedented endoperoxide-endoperoxide rearrangement. Treatment of the endoperoxides 14 and 15 with a catalytic amount of Et3N at 0° provided the azulenones 22 and 23 in high yield. Attempted cleavage of the O−O peroxide linkage in 14 and 15 with thiourea resulted, contrary to our expectation, in the formation of 22 and 23. That thiourea acts as a base instead of a reducing reagent has been observed for the first time in peroxide chemistry.

Unusual photorearrangement of 1,7-disubstituted 7-azabenzonorbornadiene

Abstract1-(11-Benzoyl-11-azatricyclo[6.2.1.02,7]undeca-2,4,6,9-tetraen-1-yl)ethanone was synthesized by cycloaddition of 2-acetyl-N-benzoylpyrrole to benzyne. Direct photolysis of 1-(11-benzoyl-11-azatricyclo-[6.2.1.02,7]undeca-2,4,6,9-tetraen-1-yl)ethanone in benzene gave N-(4-acetylnaphthalen-1-yl)benzamide. The formation of this product is discussed in terms of radical-stabilizing and destabilizing effect of electron-withdrawing group in the formation of cyclopropane ring.

Syntheses of and photochemical studies of 2,3-disubstituted 1,4-epoxy-1,4-dihydronaphthalenes

A method for synthesis of 3-methyl-1,4-epoxy-1,4-dihydronaphthalene-2-carboxylic acid and 3-methyl-1,4-epoxy-1,4-dihydronaphthalene-2-carbonitrile was developed starting from 1,4-epoxy-1,4-dihydronaphthalene; direct photolysis of 3-methyl-1,4-epoxy-1,4-dihydronaphthalene-2-carbonitrile and methyl 3-methyl-1,4-epoxy-1,4-dihydronaphthalene-2-carboxylate in benzene gave indene derivatives.