ChemInform Abstract: Structure and Reactivity of Isoanellated Heterocyclic Systems with 4n π- and (4n + 2) π-Electrons. Part 15. 2-tert.-Butyl-4-methyl-2,4-dihydropyrrolo(3,4-b)indoles. Reactions with Activated CC-Dienophiles.
Abstract
While their unsubstituted analogue (R1,R2: -H) is inert towards N-arylmaleimides, the methoxy-substituted title compounds (I) react with (II) to give the unstable cycloadducts (III) (detected by means of 1H NMR).
ChemInform Abstract
While their unsubstituted analogue (R1,R2: -H) is inert towards N-arylmaleimides, the methoxy-substituted title compounds (I) react with (II) to give the unstable cycloadducts (III) (detected by means of 1H NMR). Higher temperatures, change of solvent and addition of nucleophilic reagents result in the cleavage of the N,O-acetal in (IIIb) and formation of tetracycles such as (IV), (V), (VI) and (IX); products arising from Michael addition, however, are not observed (in contrast to the reaction of (Ib) with dimethyl acetylenedicarboxylate).
