Synthesis of 5-azaindoles via a cycloaddition reaction between nitriles and donor-acceptor cyclopropanes.

A new method for the synthesis of 5-azaindole derivatives is reported. A [3+2] dipolar cycloaddition between nitriles and a 3,4-cyclopropanopiperidine followed by SeO(2) oxidation affords the target compounds in moderate to excellent yields. The divergent nature and cost effectiveness of this method makes it very suitable for combinatorial applications in the pharmaceutical industry

Polarity Inversion of Donor–Acceptor Cyclopropanes: Disubstituted δ-Lactones via Enantioselective Iridium Catalysis

The coupling of carbonyl electrophiles at the donor position of donor-acceptor cyclopropanes is described, representing an inversion of polarity with respect to conventional reactivity modes displayed by these reagents. Specifically, upon exposure of donor-acceptor cyclopropanes to alcohols in the presence of a cyclometallated iridium catalyst modified by (S)-BINAP, catalytic C-C coupling occurs to provide enantiomerically enriched products of carbonyl allylation. Identical products are obtained upon isopropanol mediated transfer hydrogenation of donor-acceptor cyclopropanes in the presence of aldehydes. The reaction products are directly transformed to cis-4,5-disubstituted δ-lactones