Diastereoselective rearomative etherifications and aminations of 2,3,9,9a-tetrahydro-1H-carbazoles

Herein we present a rearomative diastereoselective etherification/amination reaction of 2,3,9,9a-tetrahydro-1H-carbazoles, themselves accessible via the Diels-Alder reaction of N-protected 3-vinyl-1H-indoles. We have developed a one-pot rearomative bromination/nucleophilic substitution reaction sequence employing both O- and N-centred nucleophiles, inverting the typical reactivity of 2,3,9,9a-tetrahydro-1H-carbazoles at the 4-position. Alcohols or secondary amines can be incorporated allowing access to the corresponding 4-substituted-2,3,4,9-tetrahydro-1H-carbazoles, the diastereoselectivity of the reaction being controlled by the nature of the nucleophile and the reaction conditions.