Rapid Sonogashira cross-coupling of iodoferrocenes and the unexpected cyclo-oligomerization of 4-ethynylphenylthioacetate

摘要

A systematic study into the Sonogashira cross-coupling of 1,1'-diiodoferrocene (fcl_2) confirms that the Pd(0)-P(~tBu)_3 system provides a remarkable rate increase over Pd(0)-(PPh_3)_2. Attempts to couple 4-ethynylphenylthioacetate (2) with fcl_2 instead produced a novel cyclic trimer of the former, from syn addition of S-Ac across C(=)C.