Indole (II) and 1-methylindole (VII) react with 1-arylnitrosoethylene leading to intermediate hetero-Diels—Alder cycloadducts, which suffer an 1,2-oxazine ring-opening reaction to form 3-alkylated indoles.
Indole (II) and 1-methylindole (VII) react with 1-arylnitrosoethylene leading to intermediate hetero-Diels—Alder cycloadducts, which suffer an 1,2-oxazine ring-opening reaction to form 3-alkylated indoles.
Depending on the reaction conditions, the three-component reaction of (I), (III), and an aldehyde affords three different compounds, i.e.
Review: [24 refs.