化学选择性合成N稠合杂环的有效级联方法,包括9 H-吡咯并[1,2- a ]吲哚,3 H-吡咯并[1,2- a ]吲哚和1 H-吡咯并[1,2- a ]已开发出吲哚衍生物。这种转变是通过三氟甲磺酸银(I)催化的连续Friedel-Crafts反应/ NC键在易于获得的炔丙醇和3取代的1 H-吲哚之间形成的顺序进行的。不仅可以根据炔丙醇的取代方式观察到极好的化学选择性,而且路易斯酸催化的NC键形成过程可以在无碱和无配体的条件下进行。
Brønsted acid−catalyzed synthesis of tetrasubstituted allenes and polysubstituted 2H-chromenes from tertiary propargylic alcohols
作者:Natalia Cabrera-Lobera、Noelia Velasco、Roberto Sanz、Manuel A. Fernández-Rodríguez
DOI:10.1016/j.tet.2019.05.023
日期:2019.8
A practical and environmentally benign Brønstedacid−catalyzed protocol for the preparation of all-carbon tetrasubstituted allenes, consisting in the direct SNˈ addition of tri- or dimethoxy arenes or allyltrimethylsilane to tertiary propargylic alcohols, has been developed. In addition, a straightforward synthesis of densely substituted 2H-chromenes by metal-free tandem allenylation/heterocyclization
Transition-Metal-Free, Brønsted Acid-Mediated Cascade Sequence in the Reaction of Propargyl Alcohols with Sulfonamido-indoles/-indolines: Highly Substituted δ- and α-Carbolines
作者:Karuppu Selvaraj、K. C. Kumara Swamy
DOI:10.1021/acs.joc.8b02293
日期:2018.12.21
Brønsted acid-mediated, transition-metal-free reaction of propargyl alcohols with sulfonamido-indoles/-indolines under mild conditions affords highly substituted δ- or α-carbolines in good to excellent yields. This protocol involvescascadereaction sequences of Friedel–Crafts alkylation/ [1,5]-hydrogen shift/electrocyclization/elimination/ [1,2]-aryl migration followed by aromatization. An unexpected