Synthesis and properties of (thieno[2,3-b]pyridin-3-yl)iminotriphenylphosphoranes. Molecular structure of (2-benzoyl-4-methoxymethyl-6-methylthieno[2,3-b]pyridin-3-yl)iminotriphenylphosphorane

Abstract

Iminophosphoranes, in light of their electronic structure, are promising intermediates for the synthesis of many compounds of different types [1][2][3]. In the present work, we synthesized thieno[2,3-b]-pyridinyliminophosphoranes, for which no data have been available in the literature, and studied the physicochemical properties of these compounds.Pyridinethione 1, α-haloacetic acid derivatives 2a-d, and phenacyl bromide 2e served as the starting compounds for the preparation of (thieno[2,3-b]pyridin-3-yl)iminotriphenylphosphoranes.The reaction of pyridinethione 1 with α-halocarbonyl compounds 2a-e were carried out in the presence of two equivalents of KOH to bind the hydrogen halide liberated and provide for the Thorpe-Ziegler isomerization of intermediate S-alkyl derivatives 3a-e to give 3-aminothieno[2,3-b]pyridines 4a-e (Scheme 1).3-Aminothieno[2,3-b]pyridines 4 are bright-yellow compounds, which are highly soluble in polar solvents (Table 1). Pyridines 4a and 4e have already been prepared and some of their properties have been reported in our previous work [4,5].The structure of the 3-aminothieno[2,3-b]pyridines was confirmed by IR, UV, and 1 H NMR spectroscopy ( Table 2). The IR spectra of 4a-e lacked the nitrile group band at 2210 cm -1 and thioamide group band at 1215 cm -1 characteristic for starting pyridinethione 1 but have stretching bands for the amino group N-H bond at 3465-3400 and 3330-3255 cm -1 as well as stretching bands for the conjugated carbonyl group in ester 4a __________________________________________________________________________________________

6-(Methylsulfanyl)-2-phenylthiazolo[5,4-b]pyridine

“…Thiazolopyridine derivatives have been widely studied because of their analgesic, antipyretic and anti-inflammatory properties (Couture & Grandclaudon, 1985, 1987. Most of them have a methyl or methoxy substituent attached to the pyridine ring of the thiazolopyridine unit (Kaigorodova, Osipova et al, 2004;Kaigorodova, Vasilin et al, 2004). As part of an investigation of the antitumor properties of the thiazolopyridine analogs, we report the synthesis and structure of the title compound, (I), containing a methylsulfanyl substituent attached to the pyridine ring.…”