Facile scalable reduction of N-acylated dihydrophyrazoles

A B[H.sub.3] pyridine reduction method was developed for a variety of functionalized N-acylated dihydropyrazoles, which proceed in good to high yield applicable in kilogram scale. The resulting acylpyrazolidine products that arise upon reduction were isolated in good to high yields following exposure to reaction conditions, which were shown to tolerate a variety of different functional groups.