Syntheses of coenzyme Q(3-8) are described, as well as related systems such
as plastoquinone-5. Preparation of thr higher homologues of the ubiquinone
s relies on two new conjunctive reagents, or "linchpins", each of which ult
imately corresponds to two or three prenyl units. These allow for attachmen
t of a polyprenyl halide at one end, followed by a Ni(0)-catalyzed cross-co
upling at the other terminus with a chloromethylated p-quinone.