Zinc chloride catalyzed stereoselective construction of spiropyrazolone tetrahydroquinolines via tandem [1,5]-hydride shift/cyclization sequence

A zinc chloride catalyzed tandem 1,5-hydride shift/cyclization process to form spiropyrazolone terahydroquinoline derivatives is developed. A series of new spiropyrazolone derivatives were obtained in good to high yields with good to excellent diastereoselectivities (up to 95% yield, >95 : 5 dr). Additionally, the spiropyrazolone derivatives could be converted into the corresponding novel spriopyrazolines.