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Direct catalytic asymmetric method for the synthesis of tetrahydropyranopyrazoles through allene zwitterion chemistry
- Mutyala, Raghupathi, Reddy, Venkatram R., Donthi, Ravikiran, Kallaganti, V.S. Ramakrishna, Chandra, Rajesh
- Tetrahedron letters 2019 v.60 no.10 pp. 703-706
- allene, catalytic activity, chemical reactions, diastereoselectivity, enantioselective synthesis, enantioselectivity, ketones, moieties, quinidine, zwitterions
- 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.