Organocatalytic one-pot asymmetric synthesis of functionalized spiropyrazolones: Via a Michael-aldol sequential reaction

An efficient organocatalytic method was developed for synthesizing functionalized spiropyrazolone derivatives containing four contiguous stereogenic centres by using a Michael-aldol consecutive reaction. We applied a quinine-derived squaramide catalyst to catalyze a reaction between 3-methyl-1-aryl-2-pyrazolin-5-ones and (E)-5-nitro-6-aryl-hex-5-en-2-ones, realizing the desired spiropyrazolones in moderate-to-good yields (up to 80%) with good-to-excellent stereoselectivities (up to >20:1 dr, 94% ee).