Chiral Iron Porphyrin-Catalyzed Asymmetric Cyclopropanation with α-Methyl-α-diazoesters with Enantiomeric Excess and Diastereomeric Ratios Values up to 99% and Applications

The efficient stereoselective cyclopropanation of alkenes using α-alkyl-α-diazoesters is an important organic synthesis method, but achieving high yield and high enantioselectivity under mild conditions remains a significant challenge. Here, we report a simple approach for achieving highly enantioselective cyclopropanation of alkenes under mild room temperature conditions using chiral iron porphyrin as a catalyst and α-methyl-α-diazoester as a carbene precursor. This approach is applicable to a broad range of alkenes (53 examples), with product yields up to 99%, diastereomeric ratios ( dr ) up to >99:1, and enantiomeric excess ( ee ) up to 99%. Iron porphyrin carbene species are key intermediates in this asymmetric cyclopropanation reaction, characterized by UV-visible absorption spectroscopy and 1 H NMR spectroscopy. DFT calculations indicate that the steric hindrance of the chiral pocket in the porphyrin scaffold is the primary factor determining the enantioselectivity and diastereoselectivity of the cyclopropanation products.