Direct catalytic asymmetric method for the synthesis of tetrahydropyranopyrazoles through allene zwitterion chemistry.

Graphical abstract Highlights • Allenoate zwitterion generated by nucleophilic catalysis annulates arylidenepyrazolone. • Methodology offers a facile entry to biologically important tetrahydropyranopyrazole. • The reaction proceeds with enantio- and diastereoselectivity in presence of quinidine. • The primary adduct undergoes further transformations with the initial chirality intact. Abstract The enantioselective synthesis of the tetrahydropyranopyrazole scaffold has been achieved. The quinidine catalyzed reaction of allenoates with arylidenepyrazolones proceeded with high enantio- and diastereoselectivity while the reactions of alkylidenepyrazolones were less efficient. Allene ketones also afforded tetrahydropyranopyrazole derivatives in high yields, however, with only moderate enantioselectivity. The primary adduct undergoes further functional group transformations without effecting the initially formed chiral centre. [ABSTRACT FROM AUTHOR]