Ring-closing metathesis using Grubbs' catalyst has been applied to the synt
hesis of the concave 1,10-phenanthrolines 5. Instead of a kinetically contr
olled double macrocyclization of the tetraphenol precursor 2 by two equival
ents of ditosylates or diiodides, the new three step synthesis separates th
e alkylation of 2 from the macrocyclization. After the tetraalkylation of 2
, the resulting tetraalkene 3 is cyclized by metathesis under thermodynamic
control to give the bimacrocycles 4 in up to 92% yield. Hydrogenation of t
he alkene double bonds gave the bimacrocycles 5 in considerably improved ov
erall yields (for instance for 5b from 19 to 79%).