In addition, the tricyclic fused ring systems (five-membered in between, 2r, 74%; sixmembered, 2s, 62%) are also viable substrates. The replacement of phenyl ring of 2a with a 1-naphthyl ring (2t, 83%) displays the highest yield; with a 2-thienyl ring (2u), the yield declines to 32%; the fusion of a phenyl ring to 2u (2v) restores the yield back to 63%; an alkyl moiety ( n Am, 2w, 56%; cyclopentyl, 2x, 71%) can also be used to supersede the phenyl ring without substantially compromising the reactivity. With the cyclopropanol substrate scope probed, a further coupling synthesis of alkyl-chained γdiketone (3ow, 44%; 2-phenylethyl instead of phenyl on 1a as 1r, 3rw, 44%) is verified to be feasible. An expansive check of the reactivity of various N-acyl-glutarimides (1s, 71%; 1t, 63%; 1u, 22%; 1v, 31%) with 2a as the coupling partner confirms the general applicability of the protocol described herein. With the substrate scope fully evaluated, a series of mechanistic studies are then undertaken. A reaction run between 1a and 2d in the presence of butylated hydroxytoluene (BHT), a highly effective radical scavenger, shows virtually no suppression of the reactivity (3ad, 63%) (Scheme 4a). A radical clock reaction between 1a and 2-cyclopropyl-modified 2a (2y) reveals no ring opening in the product 3ay (50%) (Scheme 4b). These two experiments exclude radical pathway as the basis for the coupling reaction. The hydroxyl group on cyclopropanol is critical for the coupling process, as with it either removed (2a ΔOH ) or protected (2a μAc ), no reaction with 1a can proceed (Scheme 4c). A competition experiment involving 1a and 2d/2g favors the electron-deficient 2g (product ratio: 3ad/3ag = 1/1.73), likely reflecting a difference in the β-carbon elimination, ring-opening reactivity (Scheme 5a). Consistent with the acid-base extrusion of oxidatively added amido ligand, glutarimide can be detected both in situ in the reaction mixture of 1a and 2d through 1 H NMR and in the purified form (73%) (Scheme 5b). A salient feature of the molecular cross-coupling chemistry described herein (vide supra) is the exemption of any stoichiometric organometallic reagent and base as a mandatory reaction component. As a typical example for comparison, an acid chloride, 1b μCl , is used in substitution for 1b to react with 2d. Extensive optimization (5 mol % Pd(P t Bu3)2) indicates that only under the extra use of a base (1.0 equiv Et3N) and preferably with the participation of a bidentate ligand (10 mol % dppf), can the reaction advances to a moderate yield (toluene, 80 o C, 12 h; 40%). Indeed, the choice of an acid chloride as the coupling partner inevitably leads to the release of a strong acid, HCl, and as such, it is of crucial importance to add a base as a neutralizing agent.