To probe the impact of catalyst structure on reaction rate and efficiency, we prepared BCC derivatives 21 and 22 bearing electron-donating and electron-withdrawing substituents, respectively, and compared their capacities to achieve the ring-closing alkyl halide-olefin metathesis of 19 to form coumarin (20) (Table ). At 20 mol% loading in wet acetonitrile at 120 °C, BCC (18) generated 20 in 41% yield. Surprisingly, BCCs 21 and 22 did not produce any amount of 20 (entries 2 and 3). Because there was no observed change to 21 or the substrate, we conclude that 21 is too electron-poor to react with the substrate at a reasonable rate (entry 2). On the other hand, 22 was alkylated readily by the substrate, but the resulting benzocinnolinium did not convert to product (entry 3). We rationalized that the 1,3-prototropic shift was inefficient with catalyst 22, and so we examined the addition of base to facilitate this step. While pyridine was ineffective because it underwent alkylation by the substrate (entry 4), both 2,6-lutidine (entry 5) and i-Pr2NEt (entry 6) led to appreciable increases in yield with catalyst 18. Even with base, catalyst 21 failed to deliver any product (entry 7), but the methoxy-substituted catalyst 22 with base produced coumarin in 76% yield.