Highly Stereoselective Brønsted Acid Catalyzed Synthesis of Spirooxindole Pyrans

Abstract

A Brønsted acid-catalyzed Prins-type cyclization sequence to construct spirooxindole pyrans in high yields and excellent diastereoselectivity has been developed. The combination of a β-hydroxy dioxinone fragment and isatin dimethyl acetal generate oxa-spirooxindoles efficiently. These compounds are diversifiable scaffolds that tap into the rich chemistry of dioxinones.

Molecular diversity of spirooxindoles. Synthesis and biological activity

“…Bifunctional catalysts 221 [126] 10 mol % [129] 10 mol % [122] 15 mol % [127] 15 mol % [123] 15 mo l% [128] 15 mol % Scheme 59 Construction of spirooxindoles through an organocatalytic cascade Michael-cyclization sequence [141][142][143]145]. A plausible mechanism for this process may probably involve the formation of arylidenemalononitriles A via Knoevenagel condensation reaction of isatins methylene active nitriles 240 using various bases.…”

Catalytic asymmetric hetero-Diels–Alder reactions of enones with isatins to access functionalized spirooxindole tetrahydropyrans: scope, derivatization, and discovery of bioactives

“…6 The diastereo-and enantioselectivities of the hDA reactions to give 3ja depended on reaction time: The initially formed major diastereomer of 3ja was gradually reduced, and this became the minor diastereomer after 6 days. The catalyst system composed of A, B, and C afforded the corresponding aldol as the major product compared to the hDA product.…”

Organocatalytic Enantioselective Assembly of Spirooxindole‐naphthopyrans through Tandem Friedel–Crafts Type/Hemiketalization

“…However, there are limited methods to access oxa‐spirooxindoles I and II (Figure ). Enantioselective assembly of oxa‐spirooxindole I was realized through Prins cyclization,– Lewis acid promoted [5+2] annulation of chiral crotylsilanes, palladium‐catalyzed decorboxylative cyclization and Brønsted acid catalysis …”