Chemoselective Hydrogen Transfer Reduction of Unsaturated Ketones to Allylic Alcohols with Solid Zr and Hf Catalysts.

Abstract

Reduction Reduction O 0220Chemoselective Hydrogen Transfer Reduction of Unsaturated Ketones to Allylic Alcohols with Solid Zr and Hf Catalysts. -Zirconium and Hafnium (not shown) catalysts, immobilized on mesoporous silica MCM-41, efficiently catalyze the hydrogen transfer reduction of various α,β-unsaturated ketones to the corresponding allylic alcohols. Chemoselectivities observed range from 94 to 98%. -(DE BRUYN, M.; DE VOS, D. E.; JACOBS*, P. A.; Adv. Synth. Catal. 344 (2002) 10, 1120-1125; Cent. Surf. Chem. Catal., Kathol. Univ. Leuven, B-3001 Leuven, Belg.; Eng.) -Nuesgen 15-063

Zr-Based MOF-808 as Meerwein–Ponndorf–Verley Reduction Catalyst for Challenging Carbonyl Compounds

“…Aside from steric effects, electronic effects are also known to have an impact on the reactivity [6,7]. Electron donating substituents (such as methyl groups) increase the electron density of the carbonyl group, thereby reducing the hydrogen transfer, especially when present in the β-position of the carbonyl group.…”

“…With the second strategy (the use of a stronger reducing alcohol [7,24]), the yield could be vastly increased to 73% (Figure 3b) with a diastereomeric excess (d.e.) for cis-carveol of 90% (see supporting information and supporting Figure S6).…”

“…Isopropyl alcohol (IPA) is the most widely used hydride donor because it is easily oxidized to acetone and is environmentally friendly [6]. The major disadvantage of IPA, however, is the reversibility of the reaction [7]. The reverse complementary oxidation of alcohols is known as the Oppenauer oxidation, resulting in an equilibrium called the Meerwein-Ponndorf-Verley-Oppenauer (MPVO) redox equilibrium [5].…”