A mild, aerobic, catalytic process for obtaining nitriles directly from alcohols and aqueous ammonia is described. The reaction proceeds via a dehydrogenation cascade mediated by catalytic CuI, bpy, and TEMPO in the presence of O2. The substrate scope is broad including various functionalized aromatic and aliphatic alcohols. This protocol enabled the one-pot synthesis of various biaryl heterocycles directly from commercially available alcohols.
A general protocol for the synthesis of N-alkyl indoles has been developed via a redox neutral C-H activation strategy using a traceless nitroso directing group. A broad scope of substituted N-alkyl indoles has been prepared in good to excellent yields using a very simple Rh catalyst system in the absence of an external oxidant or any other additive. Good to excellent regioselectivity has been achieved for asymmetrically disubstituted acetylenes.
Diverse opportunities: A Rhodium(III)-catalyzed ortho-selective olefination of arenes using a novel triazene as a directing group is reported. This method exhibits substantial post-functionalization synthetic versatility, overcoming a vital limitation in C sp 2-H activation/functionalization products: restricted structural diversity.
Indole-containing polyaromatic scaffolds are widely found in natural products, pharmaceutical agents, and π-conjugated functional materials. Often, the synthesis of these highly valuable molecules requires a multistep sequence. Therefore, a simple, one-step protocol to access libraries of polyaromatic indole scaffolds is highly desirable. Herein we describe the direct synthesis of polysubstituted indolo[2,1-a]isoquinoline analogues via a double C-H annulation cascade using triazene as an internally cleavable directing group. Evidence from HRMS and theoretical calculations suggests that an unprecedented 1,2-alkyl migration might be responsible for the in situ cleavage of the directing group. Both kinetic isotope effects and DFT calculations suggested that the alkyne insertion step is rate-limiting for the second C,N annulation reaction.
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