Polarity Inversion of Donor–Acceptor Cyclopropanes: Disubstituted δ-Lactones via Enantioselective Iridium Catalysis
摘要:
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 delta-lactones.
Synthesis of Lactones and Lactams from Vinylcyclopropane by Palladium- Catalyzed Nucleophilic Allylation
作者:Masanari Kimura、Goki Hirata、Gen Onodera
DOI:10.1055/s-0034-1378566
日期:——
the presence of diethylzinc proceeded to provide homoallyl alcohols with anti stereoselectivity. Aldimines prepared from aldehyde and primary amines in situ underwent a similar nucleophilic allylation to give homoallylamines with syn stereoselectivity. The resulting homoallyl alcohols and homoallylamines could be converted by treatment with a tetranuclear zinc cluster into γ-vinyl-δ-valerolactones and