A monomeric unit of a conformationally constrained PNA analog, E-olefinic p
eptide nucleic acid (E-OPA) containing the base thymine was synthesized in
14 steps. The key step involved a palladium (0) catalyzed cross-coupling re
action utilizing a Reformatsky reagent as nucleophile. A protecting group r
egime that is compatible with solid-phase PNA and DNA chemistries was chose
n.