The first example of a highly enantioselective Michael addition of 2-acetyl azaarenes with β,β-disubstituted nitroalkenes was achieved using a Ni(acac)2-bisoxazoline complex as a catalyst, which afforded chiral compounds with an all-carbon quaternary stereocenter bearing a CF3 group in good yields with excellent enantioselectivities (up to >99% ee). This reaction, featuring mild conditions, excellent enantioselectivity and broad generality, provides a new efficient strategy for the construction of trifluoromethylated all-carbon quaternary stereocenters.
The first highly enantioselective conjugate addition of 2-acetyl azaarenes to α-substituted-β-nitroacrylates was successfully realized under mild conditions by a Ni(II)-bisoxazoline complex, providing the desired adducts bearing an all-carbon quaternary stereocenter in high yield with excellent enantioselectivity. The products obtained in this system could be readily converted into optically active β-amino esters, succinates, lactones, and lactams.
A novel visible-light-promoted selective sulfonylation and selenylation of dienes with selenosulfonates has been developed. This technology provides mild access to a wide range of sulfonyl benzo[b]azepinones and seleno-benzo[b]azepines. Preliminary mechanistic studies suggest that the sulfonylation involves a sulfonyl radical engaged cascade process, and the selenylation is accomplished through a sequential oxidation/ electrophilic cyclization process. The large-scale operation and late-stage modification experiment reveal the promising utility of this protocol. Letter pubs.acs.org/OrgLett
The first Ni(ii)-catalyzed Mukaiyama–Mannich reaction of cyclic N-sulfonyl α-ketiminoesters with silyl enol ethers was realized and provided enantioenriched benzofused sultams containing a quaternary α-amino ester.
A novel cyclization of N-alkoxy α-halogenoacetamides with N-sulfonyl-1-aza-1,3-butadienes has been developed for the efficient preparation of 1,4-diazepinones in one step under transition metal-free conditions.
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