A base-mediated synthesis of N-hydroxy- and N-alkoxyindoles from 2-nitrostyrenes.

Sequential treatment of alkyl 2-(2-nitroaryl)-2-butenoates with potassium tert-butoxide and an electrophile, such as methyl iodide, benzyl bromide and allyl bromide, afforded N-alkoxyindoles. In related reactions, using sodium tert-pentoxide as the base with or without in situ addition of an electrophile afforded N-alkoxy- and N-hydroxyindoles, respectively. Electrophiles such as dimethylsulfate, p-tosyl chloride, and acetic anhydride afforded moderate yields of the respective N-methoxy-, N-tosyloxy, and N-acetoxyindoles, while methyl iodide, benzyl bromide, and 1-bromohexane failed to form alkylated products using sodium tert-pentoxide as the base.

Synthesis of the tricyclic indole alkaloids, dilemmaones A and B.

Dilemmaones A-C are naturally occurring tricyclic indole alkaloids possessing a unique hydroxymethylene or methoxymethylene substituent at the C2 position of the indole core and a C6-C7 fused cyclopentanone. Dilemmaone B has been prepared in 5 steps from 5-methylindan-1-one, and dilemmaone A has been prepared in 3 steps from a common precursor, 6-bromo-5-methyl-7-nitroindan-1-one. In both syntheses, key steps include a Kosugi-Migita-Stille cross coupling and a reductive cyclization using hydrogen gas and a transition metal catalyst.