Knoevenagel‐Friedel‐Crafts‐Hemiketalization Triple Cascade Reaction: A Diastereoselective Formal [1+2+3] Cyclization Towards Indenonaphthopyran Scaffolds

Abstract

A simple and efficient cascade reactionviaformal [1+2+3] cyclization of 1,3‐indanedione, aldehyde and 2‐naphthol is reported using K2CO3as a base. The advantage includes metal‐free conditions, varied substrate scope and shortened reaction duration with high diastereoselectivity (i. e., 99 : 1) resulting in the formation of two carbon‐carbon as well as two carbon‐oxygen bonds through Knoevenagel‐Friedel‐Crafts‐Hemiketalization sequence resulting in three contiguous stereocenters.

Synthesis and characterization of thiophene-derived palladium(ii) complex immobilized on FSM-16 and its application in the novel synthesis of 7-(aryl)-7,12-dihydro-6H-indeno[1,2,4]triazolo[1,5-a]pyrimidine-6-one derivatives

“…In recent years, multi-component reactions containing 1,3-indanedione have been successfully developed to synthesize spiro heterocycles, spirocycles, and fused heterocycles. 57–60 The fused heterocycles are containing the 1,3-indanedione structure from important medicinal and biological frameworks. These compounds have attracted the attention of pharmacologists and chemists due to their broad scope of biological activities.…”

Synthesis of Multisubstituted Indanedione Based Spiropyrans via Oxa‐Michael/Michael Cascade Reaction

“…[8] In continuation of our research interest towards spiropyrans using primary nitro allylic alcohol 5 (Eqn. b, Scheme 1) [9] and fused heterocyclic skeletons, [10] we envisioned that the synthesis of multisubstituted spirocyclic pyrans having four stereocenters via Oxa-Michael/Michael [11][12][13] through formal [4 + 2] cycloaddition cyclization reaction can be accomplished using ambiphilic substrates (1 C, 2 C) 2-arylidene-1,3-indanedione [14] 4 and (1 C, 4O) secondary nitroallylic alcohol 2. (Scheme 2).…”

Synthesis of fully functionalised spiropyran pyrazolone skeletons via a formal [4 + 2] cascade process using β-nitro-styrene-derived MBH-alcohols

“…On the other hand, the utility of nitro-styrene-derived MBH alcohols as 1,4- bis -ambiphiles (α-C, δ-O) has been less extensively investigated. 20 In continuation of our efforts towards the synthesis of various spirocyclic systems, 21 herein we report the synthesis of spiropyrazolone tetrahydropyran scaffolds using β-nitro-styrene-derived MBH alcohols, resulting in the formation of the desired products with 4 to 5 contiguous chiral centers through [4 + 2] annulation (eqn (d), Scheme 1).…”