Iridium-catalyzed asymmetric ring-opening reactions of oxabicyclic alkenes with secondary amine nucleophiles.

Dingqiao Yang,Yujuan Wu,Hui Wang,Ping Hu,Yuhua Long,Xiongjun Zuo,Heping Zeng

doi:10.3762/bjoc.5.53

Abstract

Iridium-catalyzed asymmetric ring-opening reactions of oxabicyclic alkenes with various aliphatic and aromatic secondary amines are reported for the first time. The reaction gave the corresponding trans-1,2-dihydronaphthalenol derivatives in good yields with moderate enantioselectivities in the presence of 2.5 mol % [Ir(COD)Cl]2 and 5 mol % bisphosphine ligand (S)-p-Tol-BINAP. The trans-configuration of 3f was confirmed by X-ray crystallography.

Highlights

Substituted dihydronaphthalenes are important molecules with different biological activities [1,2,3,4,5]
The asymmetric ring-opening (ARO) reaction involves many components of the chemical agents; we first attempted to optimize the ligand to iridium catalyst system (Scheme 1)
The iridium-catalyzed ARO reactions described in this article featured lower cost compared with rhodium

Summary

Introduction

Substituted dihydronaphthalenes are important molecules with different biological activities [1,2,3,4,5]. The desired ring-opened product 2a was obtained only in low yield (47%) with reasonable enantioselectivity (51% ee) in the iridium-catalyzed system. Among the solvents examined for asymmetric ring-opening of oxabenzonorbornadiene 1a, THF was found to be the best in terms of yield and enantioselectivity (Table 1, entry 6).

Results

Conclusion