Catalyst-controlled divergent intermolecular cycloadditions of vinylaziridines with alkynes have been developed. By using [Rh(NBD)2]BF4 as the catalyst, a [3 + 2] cycloaddition reaction was achieved with broad substrate scope and high stereoselectivity under mild reaction conditions. Moreover, the chirality of vinylaziridines can be completely transferred to the [3 + 2] cycloadducts. When the catalyst was changed to [Rh(η(6)-C10H8) (COD)]SbF6, the alternative [5 + 2] cycloadducts were selectively formed under otherwise identical conditions.

The first example of highly enantioselective fluoroarylation of gem-difluoroalkenes with aryl halides is presented by using a new chiral sulfinamide phosphine (Sadphos) type ligand TY-Phos. N-Me-TY-Phos can be easily synthesized on a gram scale from readily available starting materials in three steps. Salient features of this work including readily available starting materials, good yields, high enantioselectivities as well as broad substrate scope make this approach very practical and attractive. Notably, the asymmetric synthesis of an analogue of a biologically active molecule is also reported. The gem-difluoroalkenes are increasingly being exploited as versatile fluorinated building blocks in organofluorine synthesis [1] via mono-defluorinative [2] or fluorine retentive [3] functionalization reactions. Over the past decade, by taking advantage of easily available gem-difluoroalkenes as reliable trifluoromethyl (CF 3) precursors, many chemists reported a conceptually novel protocol for the expedient synthesis of CF 3-containing molecules through an additional fluorine source via a radical pathway or an anion/ cation mechanism (Scheme 1),which are supplement to the typical trifluoromethylation reaction. [4] In 2014, Hu and co-workers demonstrated the formation of a-trifluoromethylated benzylsilver species from the reaction of gem-difluoroalkene with AgF for the first time, and which undergoes rapid C-Ag I bond homolysis in situ to afforded the a-CF 3 benzyl radical. [5] Recently, Feng et al. [6] reported a photoredox-coupled Fnucleophilic addition induced allylic alkylation of gemdifluoroalkenes via the a-CF 3 benzyl radical intermediate (Scheme 1 a). In contrast, the Feng and Loh group [7] and Malcolmson et al. [8] realized palladium-catalyzed fluorinative allylation and arylation of gem-difluoroalkenes via a-CF 3 carbanion intermediate, and the first attempt to palladiumcatalyzed asymmetric fluoroallylation of gem-difluoroalkenes Scheme 1. Trifluoromethylation of gem-difluoroalkenes.

By taking advantage of vinyl aziridines as a heteroatom-containing five-atom component in rhodium-catalyzed intramolecular formal hetero-[5 + 2] cycloaddition reactions with alkynes, a highly efficient method for the synthesis of fused azepine derivatives at 30 °C was developed. The reaction has broad substrate scope and tolerates a wide range of functional groups. The chirality of vinyl aziridine-alkyne substrates can be completely transferred to the cycloadducts, representing an atom-economic and enantiospecific protocol for the construction of fused 2,5-dihydroazepines for the first time.

Herein we present a phoshine-catalyzed highly regio-, diastereo- and enantioselective [3 + 2] cycloaddition of γ-substituted allenoates with β-perfluoroalkyl enones, delivering a wide range of densely functionalized perfluoroalkylated cyclopentenes with three contiguous chiral stereocenters.