Synthesis and structure of new alkynyl derivatives of phenothiazine and phenoxazine. (3rd May 2016)

• Record Type: Journal Article
• Authors: Onoabedje, Efeturi A.; Okoro, Uchechukwu C.; Sarkar, Amitabha; Knight, David W.
• Is Part Of: Journal of sulfur chemistry. Volume 37:Number 3(2016)
• Page Start: 269
• Page End: 281
• Publication Date: 2016-05-03
• Subjects: Cross-coupling -- Sonogashira -- XPhos -- phenothiazine -- phenoxazine; Sulfur -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.72305
• DOI: 10.1080/17415993.2015.1131827
• Languages: English
• ISSNs: 1741-5993

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, 1 H and 13 Cnmr), ms and elemental analytical data.