A Family of Thiazolium Salt Derived N-Heterocyclic Carbenes (NHCs) for Organocatalysis: Synthesis, Investigation and Application in Cross-Benzoin Condensation

作者：Piel Isabel; Pawelczyk Marius D; Hirano Keiichi; Froehlich Roland; Glorius Frank^*

来源：European Journal of Organic Chemistry, 2011, 2011(28): 5475-5484.

DOI：10.1002/ejoc.201100870

• Organocatalysis
• Nitrogen heterocycles
• Carbenes
• Umpolung
• Cross-benzoin condensation

A family of thiazolium salt derived N-heterocyclic carbenes (NHCs) bearing sterically demanding aryl substituents on the nitrogen and with varying backbone substitution patterns have been synthesized. Investigation of the catalytic activity of these NHCs in a number of benzoin-type coupling reactions revealed markedly different levels of reactivity and selectivity. To elucidate the underlying factors leading to differences in reactivity, a study of the electronic and steric properties of these NHC catalysts was conducted. By using the best catalyst in this study, the intermolecular cross-benzoin condensation reaction was explored in more detail.

• 出版日期2011-10