A sequential ruthenium-catalyzed ring-closing metathesis–transfer hydrogenation sequence
has been established as a synthesis of chromanes starting from 2-(allyloxy)styrenes.
The sequence requires only one precatalyst, the first-generation Grubbs catalyst,
which is converted into a ruthenium hydride species in situ. Propan-2-ol serves as
a chemical trigger for the formation of the ruthenium hydride and as hydrogen source.
Key words
ruthenium - chromanes - tandem reactions - metathesis - styrenes