Heterocyclization of N-propenyl-substituted phenothiazines and phenoxazines using electrophiles in an anhydrous medium |
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Authors: | E E Sirotkina A I Khlebnikov O A Napilkova |
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Institution: | (1) Institute of Petroleum Chemistry, Siberian Branch of the Russian Academy of Sciences, Tomsk, 634021, Russia;(2) I. I. Polzunov Altai State Technical University, Barnaul, 656038, Russia |
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Abstract: | 10-Propenylphenothiazine reacts with a catalytic amount of BF3·Et2O in dry ethyl acetate via intramolecular heterocyclization of an intermediate dimeric cation to give mainly 1-ethyl-2-methyl-3-(phenothiazin-10-yl)-2,3-dihydro-1H-pyrido3,2,1-k,l]phenothiazine and a minor product through fission of phenothiazine which is 1-ethyl-2-methyl-1H-pyrido3,2,1-k,l]phenothiazine. Under similar conditions 10-propenylphenoxazine gave an oligomer (degree of polymerization 4.4) and the minor
product 1-ethyl-2-methyl-1H-pyrido3,2,1-k,l]phenoxazine likely formed similarly to the phenothiazine analog from the corresponding product of intramolecular heterocyclization
(the latter not being observed in the reaction mixture).
Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his jubilee.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1855–1860, December, 2008. |
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Keywords: | 1H-pyrido[3 2 1-k l]phenoxazines 1H-pyrido[3 2 1-k l]phenothiazines propenyl-substituted phenoxazine phenothiazine heterocyclization electrophilic catalysts |
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