| |
[摘要]：A new tandem cross metathesis-intramolecular aza-Michael reaction in which an alpha,alpha-difluorinated amide serves as a source of nucleophilic nitrogen is described. This process gives rise to a new family of fluorinated gamma- and delta-lactams. The tandem protocol is catalyzed by the Hoveyda-Grubbs second-generation ruthenium catalyst with titanium(IV) tetraisopropoxide as a co-catalyst and it is highly efficient when conjugated ketones are used as the Michael acceptors. With conjugated esters, however, it is necessary to perform a step-by-step procedure in which the cyclization event is activated by the addition of a base. An asymmetric version of the process is also evaluated. |
|
