RuPHOX-Ru-Catalyzed Selective Asymmetric Hydrogenation of Exocyclic α,β-Unsaturated Pentanones

Abstract

A RuPHOX-Ru catalyzed selective asymmetric hydrogenation of exocyclic α,β-unsaturated ketones has been developed, furnishing the corresponding chiral exocyclic allylic alcohols in high yields and with up to >99.5% ee. The reaction could be performed on a gram scale with a relatively low catalyst loading (up to 10000 S/C) without any loss in reaction activity and enantioselectivity. The resulting hydrogenated products could be easily transformed to several biologically active compounds with high asymmetric performance. The asymmetric protocol provides an efficient methodology for the synthesis of chiral exocyclic allylic alcohols.

Synthesis of Dendritic ZSM-5 Zeolite through Micellar Templating Controlled by the Amphiphilic Organosilane Chain Length

“…Condensation adducts (FC and F 2 C, see Scheme 1) are not commercially available, and preparation is based on previous works. 34 A mixture of FFL (3 g, 31.23 mmol), CPO (3.15 g, 37.47 mmol), diethyl ether (31 mL), and a 1 M NaOH solution (31 mL) was stirred at room temperature for 24 h. The mixture was diluted with 50 mL of ethyl acetate (EtOAc). The aqueous layer was separated and extracted with EtOAc (3 × 20 mL).…”

Asymmetric hydrogenation of exocyclic γ,δ-unsaturated β-ketoesters to functionalized chiral allylic alcohols via dynamic kinetic resolution

“… 1 Among them, catalytic asymmetric hydrogenation of enones has been demonstrated to be one of the most efficient, practical, and atom-economical approaches. 2 However, despite long-standing interest, the enantioselective synthesis of highly functionalized chiral allylic alcohols such as γ,δ-unsaturated β-hydroxy esters with two contiguous stereocenters remains rare and challenging. 2 The reported catalytic asymmetric methods for the synthesis of optically active chiral γ,δ-unsaturated β-hydroxy esters with two contiguous stereocenters are limited to asymmetric aldol reactions ( Scheme 1a ) 3 and ruthenium catalyzed asymmetric transfer hydrogenation of racemic α-substituted γ,δ-unsaturated β-ketoesters via a dynamic kinetic resolution (DKR) ( Scheme 1b ).…”

“… 2 However, despite long-standing interest, the enantioselective synthesis of highly functionalized chiral allylic alcohols such as γ,δ-unsaturated β-hydroxy esters with two contiguous stereocenters remains rare and challenging. 2 The reported catalytic asymmetric methods for the synthesis of optically active chiral γ,δ-unsaturated β-hydroxy esters with two contiguous stereocenters are limited to asymmetric aldol reactions ( Scheme 1a ) 3 and ruthenium catalyzed asymmetric transfer hydrogenation of racemic α-substituted γ,δ-unsaturated β-ketoesters via a dynamic kinetic resolution (DKR) ( Scheme 1b ). 4 However, most of these methodologies are restricted to provide noncyclic chiral γ,δ-unsaturated β-hydroxy esters containing two contiguous stereocenters, and no reports have been published on the enantioselective synthesis of such types of highly functionalized chiral allylic alcohols through direct asymmetric hydrogenation of the corresponding racemic enone esters via DKR.…”

Asymmetric Inverse-Electron-Demand Oxa-Diels–Alder Reaction with Morita–Baylis–Hillman Carbonates of 2-Cyclopentenone via a Palladium-Catalyzed Umpolung Strategy

“…Besides, an epoxidation reaction of the exo -cyclic double bond of 5 occurred by treatment with m CPBA ( meta -chloroperoxybenzoic acid), and a diol product 7 was finally attained with excellent diastereoselectivity followed by a hydrogenative ring-opening process. Moreover, after conversion of 5 to its acetate, a methyl group could be chemoselectively introduced to afford product 8 through a copper-catalyzed substitution reaction with CH 3 MgBr, further enriching the structural diversity of the framework.…”