Iridium-Catalyzed Asymmetric Ring-Opening of Oxabenzonorbornadienes with Phenols

A novel iridium-catalyzed asymmetric ring-opening (ARO) reaction of oxabenzonorbornadienes with a variety of phenols was reported, which afforded the corresponding <i>trans</i>-2-phenoxy-1,2-dihydronaphthalen-1-ol products in high yields with moderate to excellent enantioselectivities (up to 98% ee) under mild conditions. The trans products are formed via the enantioselective cleavage of a bridgehead carbon–oxygen bond in <b>1</b> followed by S_N2 nucleophilic attack by phenols. The effects of various bisphosphine ligands, Ag (I) salts, ammonium halides, bases, and solvents on the yield and enantioselectivity of the reaction were also investigated. The trans-configuration of the product <b>2a</b> was confirmed by X-ray crystal structure analysis. A possible mechanism for the present catalytic reaction was proposed

Iridium-Catalyzed Asymmetric Ring-Opening of Oxabenzonorbornadienes with Phenols

A novel iridium-catalyzed asymmetric ring-opening (ARO) reaction of oxabenzonorbornadienes with a variety of phenols was reported, which afforded the corresponding <i>trans</i>-2-phenoxy-1,2-dihydronaphthalen-1-ol products in high yields with moderate to excellent enantioselectivities (up to 98% ee) under mild conditions. The trans products are formed via the enantioselective cleavage of a bridgehead carbon–oxygen bond in <b>1</b> followed by S_N2 nucleophilic attack by phenols. The effects of various bisphosphine ligands, Ag (I) salts, ammonium halides, bases, and solvents on the yield and enantioselectivity of the reaction were also investigated. The trans-configuration of the product <b>2a</b> was confirmed by X-ray crystal structure analysis. A possible mechanism for the present catalytic reaction was proposed

Palladium-Catalyzed <i>syn</i>-Stereocontrolled Ring-Opening of Oxabicyclic Alkenes with Sodium Arylsulfinates

Palladium-catalyzed <i>syn</i>-stereocontrolled ring-opening reactions of oxabenzonorbornadienes with a wide range of sodium arylsulfinates were investigated, affording the desired products in good to excellent yields under an air atmosphere. This protocol provides a low-cost new viable and convenient method toward the synthesis of <i>cis</i>-2-aryl-1,2-dihydronaphthalen-1-ol with good functional group tolerance. In addition, the <i>cis</i> configuration of <b>3da</b> was established by X-ray diffraction analysis, and a plausible mechanism for the ring-opening reaction was proposed

Iridium/Copper Co-catalyzed <i>Anti</i>-Stereoselective Ring Opening of Oxabenzonorbornadienes with Grignard Reagents

Cooperative catalysis has been widely considered as one of the most powerful strategies to improve synthetic efficiency. A new iridium/copper cocatalyst was developed for the ring-opening reaction of oxabenzonorbornadienes with a wide variety of Grignard reagents, which afforded the corresponding <i>anti</i>-2-substituted 1,2-dihydronaphthalen-1-ols in high yields (up to 99% yield) under mild conditions. The effects of catalyst loading, Lewis acid, Grignard reagent loading, and reaction temperature on the yield were investigated. To the best of our knowledge, it represents the first example of ring-opening reactions of oxabicyclic alkenes with Grignard reagent nucleophiles in a <i>trans</i>-stereoselective manner

Microwave-Assisted One-Pot Synthesis of Isoquinolines, Furopyridines, and Thienopyridines by Palladium-Catalyzed Sequential Coupling–Imination–Annulation of 2-Bromoarylaldehydes with Terminal Acetylenes and Ammonium Acetate

A palladium-catalyzed microwave-assisted one-pot reaction for the synthesis of isoquinolines is developed. The reaction is carried out by sequential coupling–imination–annulation reactions of <i>ortho</i>-bromoarylaldehydes and terminal alkynes with ammonium acetate, and a variety of substituted isoquinolines, furopyridines, and thienopyridines is prepared in moderate to excellent yields (up to 86%)

Platinum(II)-Catalyzed Asymmetric Ring-Opening Addition of Arylboronic Acids to Oxabenzonorbornadienes

A new platinum­(II)-catalyzed asymmetric ring-opening addition of arylboronic acids to oxabenzonorbornadienes was developed, which afforded the corresponding <i>cis</i>-2-aryl-1,2-dihydronaphthalen-1-ol products in high yields (up to 97%) with moderate to good enantioselectivities (up to 89% ee) under very mild conditions. The effects of various ligands, catalyst loading, bases, solvents, and temperatures on the yield and enantioselectivity of the reaction were also investigated. The cis configuration of product <b>2m</b> was confirmed by X-ray diffraction analysis. A potential mechanism for the present catalytic reaction is proposed

Nickel-Catalyzed Asymmetric Ring Opening of Oxa­benzo­norborna­dienes with Arylboronic Acids

A new, versatile, and highly efficient nickel-catalyzed asymmetric ring-opening (ARO) reaction of oxabenzo­norborna­dienes with a wide variety of arylboronic acids has been developed, yielding <i>cis</i>-2-aryl-1,2-dihydro­naph­thalen-1-ols in high yields (up to 99%) with good to excellent enantioselectivities (up to 99% ee) under very mild conditions. The effects of various nickel precursors, chiral bidentate ligands, catalyst loadings, bases, solvents, and temperatures on the yield and enantioselectivity of the reaction were also investigated. A plausible mechanism was proposed to account for the formation of the corresponding <i>cis</i>-ring-opened products based on the X-ray structure of product <b>4b</b>

Platinum(II)-Catalyzed Asymmetric Ring-Opening Addition of Arylboronic Acids to Oxabenzonorbornadienes

A new platinum­(II)-catalyzed asymmetric ring-opening addition of arylboronic acids to oxabenzonorbornadienes was developed, which afforded the corresponding <i>cis</i>-2-aryl-1,2-dihydronaphthalen-1-ol products in high yields (up to 97%) with moderate to good enantioselectivities (up to 89% ee) under very mild conditions. The effects of various ligands, catalyst loading, bases, solvents, and temperatures on the yield and enantioselectivity of the reaction were also investigated. The cis configuration of product <b>2m</b> was confirmed by X-ray diffraction analysis. A potential mechanism for the present catalytic reaction is proposed

Iridium-Catalyzed Asymmetric Ring-Opening of Azabicyclic Alkenes with Phenols

The asymmetric ring-opening of azabicyclic alkenes with a variety of phenols is investigated using an iridium catalyst generated in situ from 2.5 mol % of [Ir­(COD)­Cl]₂ and 5.0 mol % of (<i>S</i>)-BINAP, which afforded the corresponding 1,2-<i>trans</i>-phenoxyamino products in excellent yield (up to 92%) with moderate to good enantioselectivities (up to 98% ee). The <i>trans</i>-configuration of the product <b>4b</b> was confirmed by X-ray crystallography

Platinum-Catalyzed Asymmetric Ring-Opening Reactions of Oxabenzonorbornadienes with Phenols

A platinum­(II)-catalyzed asymmetric ring opening of oxabenzonorbornadienes with phenols was developed, which afforded the corresponding <i>cis</i>-2-(un)­substituted phenoxy-1,2-dihydronaphthalen-1-ol products rather than the <i>trans</i> ones in excellent yields (up to 99%) with moderate to good enantioselectivities (up to 87% ee) under mild conditions. In addition, the <i>cis</i>-configuration of product <b>2b</b> was confirmed by X-ray diffraction analysis. Based on the results, a potential mechanism for the present catalytic reaction was proposed