Facile one-pot synthesis of hydroxylated 1,3-dithiane-pyrazolone hybrids

This paper presents an efficient one-pot approach for synthesizing hydroxylated 1,3-dithiane-pyrazolone hybrids. The process involves a reaction between pyrazolone derivatives, carbon disulfide, and epichlorohydrin (ECH). The structures of the produced 1,3-dithian-pyrazolone hybrids are determined based on their IR, ¹H NMR, ¹³C NMR, and Mass spectroscopic data. Analysis of the ¹H NMR spectra of compounds 4b and 4d revealed first-order splitting of the methylene hydrogens of the 1,3-dithian moiety, indicating that the OH group occupies an axial position in the preferred conformation of these derivatives. Despite the use of optically pure ECH as a starting material, racemization of products occurs during the reaction. The proposed reaction mechanism provides a rational explanation for this observation.