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 cyclometalated iridium catalyst modified by (S)-BINAP, catalytic C-C coupling occurs, providing 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.
Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712, USA.
Joseph
J
Moran
Austin G
AG
Smith
Ryan M
RM
Carris
Jeffrey S
JS
Johnson
Michael J
MJ
Krische
D000438:Alcohols / Q000737:chemistry; D002384:Catalysis; D003521:Cyclopropanes / Q000737:chemistry*; D007495:Iridium / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D013237:Stereoisomerism
D000438:Alcohols; D003521:Cyclopropanes; D007783:Lactones; D007495:Iridium