FIRST REACTIONS OF VINYLINDOLES WITH DIETHYL MESOXALATE, NITROSOBENZENE, AND CHLOROSULFONYL ISOCYANATE: NEW FUNCTIONALIZED AND ANNELLATED INDOLES

Article abstract of DOI:10.1016/S0040-4020(01)89519-3

Diethyl mesoxalate reacts with 2- and 3-vinylindoles via electrophilic substitution to give new, functionalized and annellated indoles in high regioselectivities.Regio-controlled dimerization processes occur in the reactions of the vinylindoles 5a and 8a.Nitrosobenzene reacts with 2- and 3-vinylindoles in a multi-stage sequence including regiospecific tandem hetero-Diels-Alder reactions to give the new, 2,3-difunctionalized indoles 11 and 12 which are conformationally stabilized by proton chelation.The heterocumulenechlorosulfonyl isocyanate reacts as a simple electrophile (like diethyl mesoxalate) with 2-vinylindole 5b to give the indole-3-carboxamide 14.In addition, analogous reactions of N-methylindole were also studied and, in most cases, gave comparable reactivity patterns.