Position-addressable nano-scaffolds. II. The introduction of one, two, or three addressable succinimide linkage points onto the under-surface of 'southern' cavity bis-porphyins

Cavity bis-porphyins containing up to three addressable succinimide rings on the underface are reported for the first time. This is achieved by site-selective addition of o-chloranil to the 7-oxanorbornene TT-bond of O-bridged sesquinorbornadienosuccinimide (1a) to form a scaffold a-dione, followed by condensation with porphyrindiamine (12) to produce a porphyrin-containing norbornene BLACK (13) incorporated a succinimide ring fused to the underside. Dual 1,3-dipolar coupling of (13) with alicyclic bis-epoxides (15) formed the cavity bis-porphyrins (16) containing two succinimide rings while similar 1,3-dipolar coupling with succinimide-containing bis-epoxide (17) gave the extended cavity bis-porphyrin (18) having three succinimide rings within the cavity section a similar cycloaddition/condensation strategy provides the shortest route to cavity bis-porphyrins containina a single succinimide ring yet reported.