Meerwein-Ponndorf-Verley-type reduction of dicarbonyl compounds to hydroxy carbonyl compounds and .alpha.,.beta.-unsaturated carbonyl compounds to allylic alcohols catalyzed by zirconocene and hafnocene complexes

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

“…[7,8] However, when applied to the selective reduction of a,bunsaturated ketones, these catalysts often show high selectivity for the saturated ketone or the alcohol. [12] In this paper we report on the selective reduction of a variety of a,b-unsaturated ketones using heterogenised zirconium and hafnium catalysts. [10±12] This reaction is intrinsically selective since only the carbonyl group coordinates with the Lewis acid reaction centre, while the double bond remains unactivated.…”

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

“…[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. Heterogeneous MPV catalysts of this type have previously only been applied to the reduction of ™simple∫ ketones, such as 4-tbutylcyclohexanone.…”

Bis(η5-cyclopentadienyl)dihydridozirconium

“…3 The regioselective 1,2-reduction of α,β-unsaturated carbonyl compounds to allylic alcohols is accomplished in the presence of 2-propanol (eq 6). 12, 13 The reagent mediates the chemoselective reduction of keto aldehydes to hydroxy ketones (eq 7). 13 Steroidal diketones, e.g.…”

“…12, 13 The reagent mediates the chemoselective reduction of keto aldehydes to hydroxy ketones (eq 7). 13 Steroidal diketones, e.g. androst-4-ene-3,17-dione, are reduced to the 17-hydroxy enones with high chemoselectivity (eq 8).…”

“…androst-4-ene-3,17-dione, are reduced to the 17-hydroxy enones with high chemoselectivity (eq 8). 13 Ph Crossed Aldol Condensation. Cp 2 ZrH 2 catalyzes the selective crossed aldol condensation between alicyclic ketones and aliphatic aldehydes to form the corresponding 2-alkylidenecycloalkanones (eq 10).…”