The Preparation of the Hydroxyskatoles and 5,6-Dihydroxyskatole

Abstract

A new procedure for the preparation of the hydroxyskatoles has been devised. 4-, 5-, 6-, and 7-benzyloxyindole-3-carboxaldehyde and 5,6-dibenzyloxyindole-3-carboxaldehyde have been prepared and give the corresponding benzyloxyskatoles on reduction with either LiXlH4 or ?JaBHd/Pd-C. The 4-, 5-, 6-, and 7-hydroxyskatoles and 5,6-dihydroxyskatole are readily obtained on catalytic debenzylation of the relevant benzyloxy compound. An alternative method for the preparation of the hydroxyskatoles involving hydrogenolysis of the benzyloxygramines is also described.The possible structures of by-products obtained in some instances are discussed.

Biotransformation of the Brassica Phytoalexin Brassicanal A by the Blackleg Fungus

“…3-Methylindole 2-Methylsulfoxide (7) Synthesis. Brassicanal A (10 mg), 10% palladium-charcoal (5 mg) and NaBH4 (20 mg) in 2-propanol (3 mL) was refluxed with stirring; 60 min later a further quantity (10 mg) of NaBH4 was added to the reaction mixture (Heacock and Hutzinger, 1964). After 2 h, the reaction mixture was filtered and treated as described for 6.…”

Mass Spectra of the Hydroxyindole-3-carboxylic Acids and the Hydroxyskatoles

“…The hydroxyindole-3-carboxylic acids (20) and hydroxyskatoles (21) were prepared by methods described in the literature.…”