A novel method for the synthesis of functionalized spirocyclic oxindoles by one-pot tandem reaction of vinyl malononitriles with isatylidene malononitriles

New Developments of the Principle of Vinylogy as Applied to π-Extended Enolate-Type Donor Systems

“…Some examples are reported in Figure , dealing with diversely functionalized products formed by domino reactions of cyclic α,α-dicyanoalkene pronucleophiles with Michael acceptors, through base activation in an achiral environment. As can be observed, the variety of the targeted chemotypes is wide and includes phenanthrene derivatives ( 1015 and 1016 ), 5,6-dihydroquinoline motif ( 1017 ), pyrazolo­[1,5- a ]­pyridines ( 1018 ), indenopyridine-fused spirocyclic systems ( 1019 ), spirocyclic oxindoles ( 1020 , 1021 , and 1022 ), − and benzo­[ a ]­carbazole derivatives ( 1023 and 1024 ). , Some of the compounds reported in Figure still bear stereogenic centers, but they were isolated as racemic mixtures since the reactions were catalyzed by achiral bases (commonly Et 3 N, DIPEA, or DBU).…”

Base‐Catalyzed Synthesis of Spiropyrazoloaminonitriles with Arylidene Pyrazolone and Vinylogous Malononitriles through a Cascade Michael Addition and Cyclization

“…Next, the same experiment was conducted by employing several bases like Piperidine, DMAP, DBU, DABCO, and K 2 CO 3 and results are tabulated (Table 1, entry 10-14). Solvent scrutiny studies indicated that all the solvents are compatible to produce desired product 4 in moderate to good yields (Table 1, entries [15][16][17][18][19]. However, TEA (0.3 equiv.)…”

“…For example, Paramasivan T. Perumal reported the one pot tandem reaction of vinyl malononitriles with isatylidene malononitriles in presence of TEA (Scheme 1c). [17] However, C. G. Yan stated Michael addition product from vinyl malononitriles and 3phenacylideneoxindoles in presence of DMAP (Scheme 1d). [18] In view of the importance of these compounds and their synthesis through vinylogous Michael addition followed by intramolecular nucleophilic addition, and also as a part of our ongoing research activity in this area, [19] planned a reaction of www.eurjoc.org vinyl malononitriles with arylidene pyrazolones and α,α-dicyano olefines independently in order to obtain spiropyrazoloaminonitriles and 1,6-dihydro biphenyls (Scheme 2).…”

“…On the other hand, α,α‐dicyano olefine compounds are one of the most versatile synthons for creating quaternary centre via Michael donor‐acceptor approach in organic synthesis. For example, Paramasivan T. Perumal reported the one pot tandem reaction of vinyl malononitriles with isatylidene malononitriles in presence of TEA (Scheme 1c) [17] . However, C. G. Yan stated Michael addition product from vinyl malononitriles and 3‐phenacylideneoxindoles in presence of DMAP (Scheme 1d) [18] …”

Expanding the chemical diversity of spirooxindoles via alkylative pyridine dearomatization

“…As part of our ongoing reaction-screening objective [ 12 – 13 ], we previously reported a Lewis acid catalyzed, three-component synthesis of spirooxindole pyranochromenedione derivatives using isatin and two 1,3-dicarbonyl compounds ( Scheme 1 ) [ 14 ]. Mechanistically, we believed this reaction to proceed through an intermediate isatylidene 1 [ 15 – 17 ]. As a means to support our mechanistic hypothesis, we attempted to prepare and isolate the isatylidene; however, our attempts were unsuccessful.…”