Catalytic Generation of Donor-Acceptor Cyclopropanes under <i>N</i>
-Heterocyclic Carbene Activation and their Stereoselective Reaction with Alkylideneoxindoles
作者:Liher Prieto、Eduardo Sánchez-Díez、Uxue Uria、Efraím Reyes、Luisa Carrillo、Jose L. Vicario
DOI:10.1002/adsc.201700198
日期:2017.5.17
Formylcyclopropanes undergo activation in the presence of an N‐heterocyclic carbene catalyst generating a donor‐acceptorcyclopropane intermediate with the ability to undergo ring‐opening followed by formal [4+2] cycloaddition with alkylideneoxindoles. This enables the direct enantio‐ and diastereoselective synthesis of tetrahydropyrano[2,3‐b]indoles through the use of a chiral NHC catalyst.
甲酰基环丙烷在N杂环卡宾催化剂的存在下发生活化,生成供体-受体环丙烷中间体,该中间体具有开环能力,然后与亚烷基亚氧吲哚进行正式的[4 + 2]环加成反应。这样可以通过使用手性NHC催化剂直接对映和非对映选择性合成四氢吡喃并[2,3- b ]吲哚。
Enantioselective addition of nitromethane to α-keto esters catalyzed by copper(<scp>ii</scp>)–iminopyridine complexes
作者:Gonzalo Blay、Victor Hernández-Olmos、José R. Pedro
DOI:10.1039/b716446g
日期:——
The coppercomplex of a chiral iminopyridine easily prepared from (R)-(-)-fenchone and picolylamine catalyzes the enantioselective Henry (nitroaldol) reaction between nitromethane and alpha-keto esters. Good yields and modest to good enantioselectivities are obtained for a wide range of alpha-keto esters, bearing aromatic, alkyl or alkenyl groups attached to the ketone carbonyl group.