Design plan. Due to facile transmetalation, unprotected alkynyl organoborons (i.e., boronic acids or esters) are incompatible with Rh-catalyzed [2+2+2]cycloadditions. Consequently, a suitably protected organoboron would be required for this synthetic strategy. We envisioned a process based on the use of a BMIDA-functionalized propargyl alcohol (1, Scheme 2a). Cycloaddition with a diyne (e.g., 2) would generate a BMIDA-functionalized benzyl alcohol derivative (3) that, upon treatment with a mild base, would induce BMIDA deprotection, enabling the formation of the BOB ring system (4). This immediately posed a challenge to the proposed catalysis: the Rh-catalyzed [2+2+2]cycloaddition is sterically controlled, with catalytic turnover directly related to the steric footprint of the alkyne substituents. With a combined A-value of >6, BMIDA-functionalized alkynes are ostensibly incompatible with this catalysis; however, coordinating functional groups are known to improve turnover. Accordingly, we considered that catalysis would be possible based on chelation assistance from the propargyl alcohol offsetting the steric deactivation from the BMIDA (Scheme 1d).