A highly efficient rhodium-catalyzed formal C–H insertion reaction between indoles and 1-diazonaphthoquinones has been established, providing a novel protocol for the atroposelective synthesis of axially chiral C2-arylindoles (up to 99:1 er) under mild reaction conditions. Typically, only 1 mol % of Rh2(S-PTTL)4 is used and the chelation group is not needed for this conversion.

An enantioselective cyclopropanation reaction of Nsubstituted 2-pyridones with diazo compounds has been realized by using a chiral rhodium complex as the catalyst, and the corresponding chiral cyclopropanes could be formed in good yields with high enantioselectivities. Moreover, using acceptor−acceptor dimethyl 2-diazomalonate as the carbene precursor, a novel 1,4rearrangement of a Boc group from N to C has also been discovered under rhodium catalysis.

We present here a rhodium-catalyzed reaction between N-acyl pyridazinones and diazoacetates, leading to pyridazine derivatives in good yield under mild reaction conditions. This whole sequence probably proceeds through a carbene insertion into a C�O bond and an unprecedented 1,4-Nto-O acyl rearrangement reaction.

A phosphoric acid-catalyzed regio- and enantioselective N2-propargylation of pyridazinones has been achieved, providing chiral N2-alkylated pyridazinones in moderate to good yields (up to 93%) with good enantioselectivities (up to 96%...