Efficient synthesis of a molecular knot by copper(I)-induced formation of the precursor followed by ruthenium(II)-catalysed ring closing metathesis

A double-stranded helix constructed around two copper(I) centres used as templates and bearing four terminal alkenes, is converted into a trefoil knot in 74% yield by ruthenium(II)-catalysed ring closing methathesis (RCM); the cyclic alkenes can be quantitatively reduced by catalytic hydrogenation to afford the copper(I)-complexed 82-membered knotted ring.