Preparation of 4-amino-1-butanol (I) comprises: (a) catalytically isomerising but-2-ene-1,4-diol (II) to give a mixture (III) of 4-hydroxybutyraldehyde (IIIa) and 2-hydroxytetrahydrofuran (IIIb); and (b) converting (III) into (I) by aminative catalytic hydrogenation (i.e. reductive amination). Steps (a) and (b) are claimed per se. The isomerisation catalyst is a combination of an iridium compound with a tertiary phosphine or phosphite.
