Intramolecular Palladium-Catalyzed Ring Opening of Oxabenzonorbornadienes with C₁-Tethered Aryl Halides

Abstract

The novel intramolecular ring opening of oxabenzonorbornadienes with C1-tethered aryl halides was investigated using palladium catalysts to form fused tetracyclic frameworks. The reaction was generally found to synthesize 1,2-dihydronaphthalen-1-ol products with mild selectivity but was capable of synthesizing dehydrated naphthalene products in excellent yield and selectivity. Substituent effects on oxabenzonorbornadiene and on the iodoarene were explored along with the effects of varying tether length, where an efficient reaction was observed in nearly all cases. A total of 16 examples are reported with yields ranging from 0 to 96%.

Biobased C6-Furans in Organic Synthesis and Industry: Cycloaddition Chemistry as a Key Approach to Aromatic Building Blocks

“…Examples of this type of aromatization are summarized in Table . Aryl, heteroaryl, and allyl substituents can be introduced using this approach with moderate to excellent yields. …”

A DFT Study on the Mechanism and Origin of Regioselectivity in the Rhodium/Diene‐Catalyzed Ring‐Opening Reactions of C1‐Substituted Oxabenzonorbornadienes with Arylboronic Acids

“…Of particular interest are nucleophilic ring‐opening reactions of oxabicyclic alkenes, as they provide access to a broad family of synthetic building blocks bearing multiple stereocenters in a single step [6] with many of these functionalized intermediates useful in natural product synthesis and as motifs in medicinal chemistry [7a,b] . Such ring‐opening reactions have been carried out using a variety of carbon and heteroatom nucleophiles in the presence of Pd, [8a–f] Ni, [9a–d] Ru, [10] , Ir, [11a–c] and Rh [12a–e] complexes.…”

Palladium‐catalyzed Synthesis of Fused Carbo‐ and Heterocycles

“…Tam and his co‐workers investigated the reaction of intramolecular ring‐opening of oxabenzonorbornadienes with C 1 ‐tethered aryl halides via palladium catalysts (Scheme 24). [34] Under this optimized reaction condition, substrate 69 reacted with 10 mol% of a palladium catalyst, a catalytic amount of zinc, 4.0 equiv. triethylamine in N,N ‐dimethylformamide solvent under 20 °C temperature for 4 h to give favorable product 70 in 84% yield.…”

“…Intramolecular ring-opening of oxabenzonorbornadienes by Tam and his co-workers. [34] Scheme 25. Synthesis of annulated γ-carbolines and heteropolycycles via intramolecular annulation of alkynes by Larock group.…”