RESUMO
A poly trifluoromethylated chiral spirocyclic phosphoric acid was developed and employed with hexafluoroisoproyl alcohol (HFIP) to render the catalytic asymmetric Mukaiyama-Mannich reaction of difluoroenoxysilanes with in situ formed ketimines. This unique multiple-fluorine system provides rapid access to difluoromethylated tetrasubstituted stereocenters in isoindolones with wide substrate scope under mild conditions. Further synthetic transformations to enantioenriched CF2H-isoindolones and CF2-decorated fused isoindolones were also implemented with good efficiency.
RESUMO
The construction of carbon-carbon bonds is a central tenet of modern synthetic chemistry. Metal-catalyzed C-H functionalization can serve as a particularly powerful tool for achieving carbon-carbon bond formation. This review summarizes the early adventures and recent advancements in catalytic transformation of unactivated C(sp3)-H bonds into C(sp3)-C(sp3) bonds. To date, three main strategies have emerged to enable this transformation, namely, metallocarbene-triggered C(sp3)-H alkylation, auxiliary-directed C(sp3)-H alkylation, and photo-induced C(sp3)-H alkylation. Compared with traditional cross-coupling reactions having both coupling partners activated with functional groups or base-promoted enolate chemistry, catalytic alkylation of unactivated C(sp3)-H bonds for C(sp3)-C(sp3) bond formation not only offers novel disconnections in retrosynthetic analysis, but also represents the future trend in green and atom-economic chemistry.
RESUMO
A zinc-/quinine-mediated enantioselective Aldol-type reaction of trifluorodiazoethane (CF3CHN2) with various aldehydes is described. This study demonstrated the feasibility of utilizing CF3CHN2 as an effective hard nucleophile in catalytic asymmetric transformations. Furthermore, the synthetic utility of this protocol is exemplified by the construction of a diverse set of chiral ß-trifluoromethylated alcohols, including a valuable HDAC inhibitor precursor.