Collect. Czech. Chem. Commun. 1990, 55, 2963-2966

Formation of acetals and cleavage of the five-membered ring in the bromination of isatin in alcohols

Jiří Gaspariča, Tomáš Vontora, Antonín Lyčkab and Dobroslav Šnoblb

a Faculty of Pharmacy, Charles University, 501 65 Hradec Králové
b Research Institute of Organic Syntheses, 532 18 Pardubice-Rybitví


Bromination of isatin (I) in alcohols affords in good yield 5,7-dibromo-3,3-dialkoxy-2-indolinones (IIIa and IIIb) which arise by reaction catalysed with hydrogen bromide liberated in the bromination. The reaction affords also minor amounts of 2,4,6-tribromoaniline (IV) formed by splitting off of two carbon atoms from the isatin five-membered ring.