Rhodium‐Catalyzed Enantioselective Isomerization of meso‐Oxabenzonorbornadienes to 1,2‐Naphthalene Oxides

Abstract

Herein we describe a rhodium-catalyzed enantioselective isomerization of meso-oxabicyclic alkenes to 1,2-naphthalene oxides. These potentially useful building blocks can be accessed in moderate to excellent yields with impressive enantioselectivities. Additionally, experimental findings supported by preliminary computations suggest that ring-opening reactions of bridgehead disubstituted oxabicyclic alkenes proceed through the intermediacy of these epoxides and may point to a kinetically and thermodynamically favored reductive elimination as the origin for the observed enantioselectivities.

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

“…Several methods for generating benzyne for transformations were described (Scheme , methods A, D, C). The resulting substances served as starting compounds for aromatic derivatives. …”

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

“…Transition‐metal‐catalyzed reactions of oxabicyclic derivatives have been an intense area of research in the last 20 years [1a–c] . Over the years, many interesting transformations have been investigated such as cycloadditions, [2a–f] isomerizations, [3a–e] dimerizations, [4a–c] among other reactions that have been reported [5a–c] . 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] .…”

Chemical Transformations of Biomass-Derived C6-Furanic Platform Chemicals for Sustainable Energy Research, Materials Science, and Synthetic Building Blocks

“…BHMF was used for preparation of a series of meso -oxabenzonorbornadienes OBNDs by the Diels–Alder reaction of BHMF and benzyne followed by functionatization of hydroxyl groups. OBNDs were involved into Rh-catalyzed enantioselective isomerization to 1,2-naphthalene oxides NPOs (Scheme ), which were obtained with moderate to high yields and ee up to 99% …”