Efeturi A. Onoabedje, U. Okoro, Amitabha Sarkar
Feb 19, 2016
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Influential Citations
12
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Journal
Journal of Sulfur Chemistry
Abstract
ABSTRACT New alkynyl derivatives of phenothiazine and phenoxazine were obtained via Sonogashira cross-coupling reactions. This was achieved by first synthesizing the intermediates 6-chloro-5H-benzo[a]phenothiazin-5-one, 6-chloro-5H-benzo[a]phenoxazin-5-one and 6-chloro-5H-naphtho[2,1-b]pyrido[2,3-e][1,4]oxazin-5-one by anhydrous base-catalyzed condensations between 2,3-dichloro-1,4-naphthoquinone and 2-aminothiophenol, 2-aminophenol and 2-aminopyridinol, respectively .The cross-couplings of these electron-rich chlorophenothiazine and chlorophenoxazine intermediates with terminal alkynes, employing 4 mol% Pd and 7 mol% XPhos in the presence of base in acetonitrile at 80°C, afforded the highly colored alkynylated derivatives in good yields. These reaction conditions allowed the incorporation of both unprotected N-H and carbonyl groups. Structural assignments were established by spectroscopic (UV, IR, 1H and 13Cnmr), ms and elemental analytical data.