One-Pot Synthesis of Antitumor Agent PMX 610 by a Copper(II)-Incorporated Mesoporous Catalyst

PMX 610 ((2-(3,4-dimethoxyphenyl)-5-fluoro-benzothiazole) is a benzothiazole derivative, which shows potent antitumor properties. In this study, copper(II)-chelated pyrazole functionalized SBA-15 mesoporous silica (Cu-Py-SBA-15) as a heterogeneous green catalyst was developed for the synthesis of substituted benzothiazole derivatives including PMX 610. The preparation of pyrazole functionalized SBA-15 (Py-SBA-15) was achieved by postsynthetic modification of mesoporous silica SBA-15 with 3-aminopropyltriethoxy-silane followed by the Schiff-base condensation with 1-phenyl-3-(2'-hydroxypheny1)-4-formyl pyrazole. The reaction of Py-SBA-15 with CuCl2 center dot 2H(2)O in absolute ethanol afforded the Cu-Py-SBA-15 catalyst. The as-synthesized catalyst was fully characterized by several techniques including powder X-ray diffraction, high-resolution transmission electron microscopy, electron paramagnetic resonance spectroscopy, X-ray photoelectron spectroscopy, C-13 cross-polarization magic angle spinning NMR, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and N-2 adsorption/desorption measurements. A one-pot-three-component approach in aqueous medium using the Cu-Py-SBA-15 catalyst was exploited for direct synthesis of PMX 610. The novel heterogeneous green catalyst offers high catalytic recyclability without considerable loss of catalytic activity. The present synthetic strategy is valuable in the preparation of PMX 610 on account of the use of readily available and inexpensive starting materials, excellent recyclability of the catalyst, and sustainable catalytic protocol.