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A facile synthesis of Pechmann dyes has been accomplished by the reaction of substituted N-phenacyl-4-dimethylaminopyridinium halides with dimethyl maleate in the presence of DBU. Based on a related 4-DMAP elimination product and an isolated monolactone intermediate a reaction mechanism has been proposed. The scope of this synthetic method is determined by the availability of α-haloaroyl or heteroaroyl derivatives. DBU=1,8-diazabicycloundec-7-ene, DMAP=4-dimethylaminopyridine. [ABSTRACT FROM AUTHOR]

The reaction of 10-azidoacetyl-10 H-phenothiazine with olefinic dipolarophiles depends on the reaction temperature. In refluxing toluene, a mixture of enamine and aziridine is formed in 3:1 ratio. The reaction mechanism appears to involve a Michael-type addition of the nucleophilic N azide atom to the olefinic double bond. In chloroform, a cycloaddition reaction takes place with the formation of a 4,5-dihydro-1,2,3-triazole. The heating of dihydrotriazoles in toluene is accompanied by nitrogen elimination leading to a mixture of enamine and aziridine in 1:3 ratio. J. Heterocyclic Chem., 2011. [ABSTRACT FROM AUTHOR]

Phenothiazine derivatives of type (III) and (IV) are prepared using click chemistry approach. [ABSTRACT FROM AUTHOR]

The primary products of the double 1,3-dipolar cycloaddition of pyridinium ylides to olefins (II) are the tricyclic enamines (IV). [ABSTRACT FROM AUTHOR]