Ruthenium-based complexes bearing saturated chiral N-heterocyclic carbene ligands: Dynamic behavior and catalysis

被引：45

作者：

Grisi, Fabia ^{[1
]}

Costabile, Chiara ^{[1
]}

Gallo, Emanuela ^{[1
]}

Mariconda, Annaluisa ^{[1
]}

Tedesco, Consiglia ^{[1
]}

Longo, Pasquale ^{[1
]}

机构：

[1] Univ Salerno, Dipartimento Chim, I-84084 Salerno, Italy

来源：

ORGANOMETALLICS | 2008年 / 27卷 / 18期

关键词：

D O I：

10.1021/om800459y

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

The synthesis of Ru-based catalysts, presenting saturated chiral C(2) symmetric (3, 5) and C, symmetric (4) N-heterocyclic carbene (NHC) ligands bearing N-(S)-phenylethyl groups, was carried out. Variable-temperature NMR studies were conducted to investigate the interconversion of atropisomers in solution. The complex behaviors were rationalized evaluating the rotation barrier of alkylidene and NHC groups around the C-Ru bonds, by DFT calculations. Comparison between NMR data and DFT calculations suggested that interconversion between different atropisomers, which occurs at room temperature, is due to the free rotation of the benzylidene group around the Ru = C bond. The activity and stereoselectivity of 3-5 were investigated in ring-closing metathesis (RCM), asymmetric ring-closing metathesis (ARCM), cross-metathesis (CM), and ring-opening metathesis polymerization (ROMP). 4 showed the highest activity in all reactions and gave a significantly low E:Z ratio in the CM reaction. Modest enantioselectivity in the ARCM of an achiral triene was observed in the presence of C(2) symmetric catalyst 5.

引用

页码：4649 / 4656

页数：8

共 52 条

[1] Asymmetric synthesis with N-heterocyclic carbenes.: Application to the copper-catalyzed conjugate addition [J].