Phosphine‐Catalyzed (3+2) Annulation of Morita‐Baylis‐Hillman Carbonates with Pyrazolinone‐Derived Ketimines: Synthesis of Spirodihydropyrrole‐Dihydropyrazolones

A phosphine-catalyzed (3+2) annulation of Morita-Baylis-Hillman carbonates with pyrazolinone-derived ketimines has been achieved to give various spirodihydropyrrole-dihydropyrazolones in moderate to high yields with good diastereoselectivities. The reaction tolerated diverse MBH carbonates and ketimines. Both scale-up reaction and further transformation of the product were successfully performed. In addition, up to 98 % ee of chiral product was obtained with the use of chiral bifunctional phosphine. Phosphine-catalyzed (3+2) annulation of Morita-Baylis-Hillman carbonates with pyrazolinone-derived ketimines gave a variety of functionalized spirodihydropyrrole-dihydropyrazolones in moderate to high yields with good diastereoselectivities.image