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Please login to access the full content or check if you have access via2.12.4.2 Reactions Using Chiral Iron Catalysts
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Liu, L.; Wang, D.; Li, C. -J., Science of Synthesis: Stereoselective Synthesis, (2011) 2, 614.
An iron(II) complex with the hindered bis[(hydroxyethyl)dihydrooxazole]pyridine (he-pybox) derived ligand 102 shows improved catalytic activity and enantioselectivity for asymmetric Mukaiyama aldol reactions in aqueous media. This water-stable chiral Lewis acid promotes condensation of aromatic silyl enol ethers (e.g., 103) with a range of aldehydes in good yields with excellent syn diastereoselectivity and up to 92% enantiomeric excess for the condensation products (e.g., 104) (Scheme 43).[71] The combination of the same ligand with zinc(II) salts also generates a remarkably efficient and water-compatible chiral Lewis acid.
Meeeee 88 Meeeeeeeee Meeeeeeee Meeeeeee ee Meeeeee Meeee Meeeeeeee ee e Meeeee Meee(MM) Meeeeeee[88]
Meeeeeeeeeee Meeeeeeee
8-Meeeeee-8-eeeeee-8-eeeeee-8-(8-eeeee)eeeeee-8-eee (888); Meeeeee Meeeeeeee:[88]
M eeeeeee ee eeeeee eeeeee (M,M)-888 (88 ee, 8.88 eeee, 88 eee%) eee MeMe8 (8.8 ee, 8.88 eeee, 88 eee%) ee eeeeeeeeeeee MeMM/M8M (8:8; 8.8 eM) eee eeeeeee ee 8 °M eeeee eeeee eeeee eee ee eee eeeee eee eeeeeeee ee eeeeeeee (88–88 eee). Me eee eeeeeeeee eeee eee eeee eeee eeeee eeeee eeee eeeee 888 (888 µM, 8.8 eeee) eee 8-MeeMMM (8.8 eeee), eee eee eeeeeeeee eeee eee eeeeeee ee 8 °M eee 8 e eeeee eeeee. Mee eeeeeee eee eeeeeee eeee e-MeMMe eee eeeeee eeee M8M eee eeeee. Mee eeeeeee eeeee eee eeeee eee eeeeeeeeeeee, eee eee eeeeeee eee eeeeeeee ee eeeeeeeeeeeeee (eeeeee eee, eeeeeeeee MeMMe/eeeeee 8:8); eeeee: 88%; ee (eee/eeee) 88:8; 88% ee (eee).
References
[71] | Meeeeeeee, M.; Meeeeeeeee, M.; Meeeee, M.; Meeeeeeee, M., M. Mee. Meee., (8888) 88, 8888. |