Abstract
A series of enantioselective cyclopropanation reactions of substituted alkenes with diazoacetates was investigated in the presence of Cu(OTf)2 with C2-symmetric planar-chiral bridged 2,2′:6′,2″-terpyridines. Planar-chiral terpyridine-copper complexes exhibited moderate diastereomeric excesses with good enantioselectivities of cis-cyclopropane products in catalytic asymmetric cyclopropanation reactions of various styrene derivatives with ethyl diazoacetate. A remote steric effect was found to enhance enantioselectivity for the cyclopropanation induced by a sterically demanding substituent beyond the ansa-bridge of pyridinophane ligands on the other side of the reaction site as a relay of steric influences through flexible cyclophane bridges.
Original language | English |
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Pages (from-to) | 1898-1903 |
Number of pages | 6 |
Journal | Tetrahedron Letters |
Volume | 56 |
Issue number | 14 |
DOIs | |
Publication status | Published - 2015 Apr 1 |
Keywords
- Asymmetric cyclopropanation
- Copper carbenoid
- Planar chirality
- Remote steric effect
- Terpyridine
ASJC Scopus subject areas
- Biochemistry
- Drug Discovery
- Organic Chemistry