Finally, it was important to develop Negishi coupling conditions that did not require the use of an isolated diorganozinc reagent. Therefore an arylzinc nucleophile was generated insitu from 4-bromoanisole by a standard approach (lithium/halogen exchange and trapping with ZnCl2 in THF). The crude arylzinc nucleophile then was combined with the crude product from the reaction of 1a with BCl3 and this mixture under the same palladium catalyzed coupling conditions formed the C-C coupled (and B-arylated) product 13 in a 35% isolated yield. While the isolated yields from these transformations appear modest, they are the combined yields for the trans-haloboration and the cross coupling steps, thus involve making O-B, C-B and C-Cl bonds and then converting the B-Cl and the C-Cl units into B-C bonds. Thus this combined trans-haloboration -Negishi coupling protocol (requiring only one work-up step) is an attractive way to make C4 functionalized analogues of important intermediates (e.g. A, Fig. ) used in the synthesis of ultra-broad spectrum β-lactamase inhibitors.