Catalysis with chalcogen bonds: neutral benzodiselenazole scaffolds with high-precision selenium donors of variable strength.

Céline Besnard,Jiri Mareda,Stefan Matile,Naomi Sakai,Sebastian Benz

doi:10.1039/c7sc03866f

Abstract

The benzodiselenazoles (BDS) introduced in this report fulfill, for the first time, all the prerequisites for non-covalent high-precision chalcogen-bonding catalysis in the focal point of conformationally immobilized σ holes on strong selenium donors in a neutral scaffold. Rational bite-angle adjustment to the long Se-C bonds was the key for BDS design. For the unprecedented BDS motif, synthesis of 12 analogs from o-xylene, crystal structure, σ hole variation strategies, optoelectronic properties, theoretical and experimental anion binding as well as catalytic activity are reported. Chloride binding increases with the depth of the σ holes down to KD = 11 μM in THF. Catalytic activities follow the same trend and culminate in rate enhancements for transfer hydrogenation of quinolines beyond 100 000.

Highlights

The benzodiselenazoles (BDS) introduced in this report fulfill, for the first time, all the prerequisites for noncovalent high-precision chalcogen-bonding catalysis in the focal point of conformationally immobilized s holes on strong selenium donors in a neutral scaffold
Chalcogen bonds originate from the s holes on electronde cient sulfur, selenium, tellurium but not oxygen atoms.[10]
Produced by the anti-bonding s* orbitals, the two s holes locate in plane with the two covalent bonds (Fig. 1)

Summary

Introduction

The benzodiselenazoles (BDS) introduced in this report fulfill, for the first time, all the prerequisites for noncovalent high-precision chalcogen-bonding catalysis in the focal point of conformationally immobilized s holes on strong selenium donors in a neutral scaffold. The weak sul de donors in BDS 1 produced shallow s holes on the Se donors, which resulted in undetectable chloride binding in THF and computed interaction energies for chloride complexes of maximal Eint 1⁄4 À37.2 kcal molÀ1 (Table 1, entry 3).

Results

Conclusion