抄録
We have designed and synthesized novel bifunctional hydrogen-bond (HB) donor catalysts bearing a benzothiadiazine or a quinazoline scaffold, whose HB-donating activity as well as recognition modes of the substrates were found to be significantly different from thiourea-typed organocatalysts by comparison of their 1H NMR studies, X-ray crystallographic analyses, spectrophotometric analyses, and computational investigations. We found that quinazoline-typed catalysts were effective for the highly enantioselective hydrazination of 1,3-dicarbonyl compounds and that benzothiadiazine-type catalysts showed great activity for the asymmetric isomerization of alkynoates to allenoates. In both cases, these newly developed catalysts were much more efficient than thiourea-typed organocatalysts, indicating that the HB-donating moiety of the catalysts was important for the recognition and activation of the substrates to facilitate the reaction.
