A reinvestigation of the Meerwein‐Ponndorf‐Verley reduction A highly efficient variation using zirconium catalysts

Abstract

A new variation of the Meenvein-Ponndorf-Verley reduction based on mechanistic considerations is presented. Under optimized conditions 1-(4-dimethylaminophenyl)ethanol was used as the reducing alcohol (2-4 equiv.), Zr(O-tBu)4 as the catalyst (0.2 equiv.), and toluene or cyclohexane as the solvent. Aldehydes and ketones (if not extremely sterically hindered) were reduced to the corresponding alcohols at room temperature mostly within 2-4 h in essentially quantitative yield. a,P-Unsaturated carbonyl compounds cleanly react in a 1,2-mode to afford the corresponding allylic alcohols.In spite of the cheap hydrogen equivalent (e.g. 2-propanol) the classical protocol of the Meenvein-Ponndorf-Verley reduction (MPV reduction, has been largely replaced by reducing agents such as borohydrides or aluminium hydridesL3]. One of the reasons for the decrease in application may be the relatively drastic reaction conditions (2a) of Nern~t [~]. Logarithmation and insertion of the constants result in equation (2b). For example, a difference in redox potential of 0.1 V corresponds to an equilibrium constant of K = 2390.

Transfer Hydrogenation Including the Meerwein‐Ponndorf‐Verley Reduction

“…The application of catalysts based on metals such as ytterbium (see Table 20.7, entries 6 and 20) and zirconium [85,86] has been reported.…”

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

“…This agrees with the idea that coordination of alcohol and ketone on MPV catalysts is easiest in apolar media. [10] The presence and the nature of the siliceous support have a remarkable effect on the activity of the catalyst ( Table 1, entries 7 ± 9). In experiments with identical total Zr concentrations, a homogeneous catalyst was compared with heterogeneous Zr catalysts based on MCM-41 or MCM-48.…”

“…Recommended standard MPV protocols with homogeneous catalysts employ regularly between 20 and 100 mol % of metal catalyst. [10] …”

“…MPV reactions are often performed with stoichiometric amounts of soluble metal compounds. [10] The use of heterogeneous catalysts has received much less attention, [13±16] while reactions with unsaturated ketones have hardly been studied. [12] In this paper we report on the selective reduction of a variety of a,b-unsaturated ketones using heterogenised zirconium and hafnium catalysts.…”

Catalytic properties of tin-containing mesoporous molecular sieves in the selective reduction of carbonyl compounds (Meerwein–Ponndorf–Verley (MPV) reaction)

“…The potential of a broad spectrum of catalysts in the MPV reduction is well documented. In addition to the classical aluminium isopropoxide catalyst [19], catalytic applications of other isopropoxides such as zirconium(IV) isopropoxide [20,21] and lanthanide isopropoxides [22] in the MPV reaction, also have been reported. However, extensive interest have been laid on the development of heterogeneous catalysts for the MPV reaction as the homogeneous catalysts are required in stoichiometric amounts and seperation of catalysts is a tedious process after the completion of the reaction.…”