Facile Synthesis of Enantiopure Sugar Alcohols: Asymmetric Hydrogenation and Dynamic Kinetic Resolution Combined

Abstract

An unprecedented Ir/f‐amphox‐catalyzed asymmetric hydrogenation of racemic 2,3‐syn‐dihydroxy‐1,4‐diones is presented involving dynamic kinetic resolution, which produces (1R,2R,3R,4R)‐tetraols. This protocol constitutes an efficient and straightforward approach to accessing sugar alcohols bearing four contiguous stereocenters. The strategy exhibits various advantages over existing methods, including excellent yields (up to 98 %), exceptional stereoselectivities (up to 99:1 dr, 99.9 % ee), operational simplicity and substrate generality. Moreover, the nature of the reaction was revealed as a stepwise transformation by in situ Fourier‐transform infrared spectroscopy and isolation of intermediates.

Stereoselective Synthesis of cis-2-Ene-1,4-diones via Aerobic Oxidation of Substituted Furans Catalyzed by ABNO/HNO3

“…The reaction of the oxidation product 2,5-diphenylfuran ( 1k ) with BrCH 2 NO 2 in the presence of K 2 CO 3 produced the nitrocyclopropane 4 in 76% overall yield, which is the key synthetic intermediate of natural products . The dihydroxylation of 2c afforded the 2,3-dihydroxy-1,4-dione 5 in 56% overall yield, and the products are key intermediates for the synthesis of sugar alcohols and natural products . The crude oxidation product 2,5-dimethylfuran ( 1a ) was reacted with 5-methylcyclohexane-1,3-dione to give the corresponding tetrasubstituted furan 6 in 51% total yield …”

Selective and Scalable Synthesis of Sugar Alcohols by Homogeneous Asymmetric Hydrogenation of Unprotected Ketoses

“… [15] We now report an asymmetric hydrogenation of unprotected ketoses with a simple and commercially available catalyst on multi‐gram scale (Scheme 1 c). [16] …”

“…now report an asymmetric hydrogenation of unprotected ketoses with a simple and commercially available catalyst on multi-gram scale (Scheme 1 c). [16] We commenced our work with screening a library of over 70 catalytic systems (loading: 1 mol %). l-Sorbose (1 b, 1 mmol, c = 0.5 m in MeOH) was chosen as the substrate, which is an intermediate of the industrial synthesis of lascorbic acid and, hence, readily available at low cost.…”

Selektive und skalierbare Synthese von Zuckeralkoholen durch homogene asymmetrische Hydrierung von ungeschützten Ketosen

“… [15] Wir berichten nun über eine asymmetrische Hydrierung ungeschützter Ketosen mit einem einfachen und kommerziell erhältlichen Katalysator im Multi‐Gramm‐Maßstab (Schema 1 c). [16] …”

“…[15] Wir berichten nun über eine asymmetrische Hydrierung ungeschützter Ketosen mit einem einfachen und kommerziell erhältlichen Katalysator im Multi-Gramm-Maßstab (Schema 1 c). [16] Wir begannen unsere Arbeit mit dem Screening einer Bibliothek von über 70 katalytischen Systemen (Beladung: 1 Mol-%). Als Substrat wurde l-Sorbose (1 b, 1 mmol, c = 0.5 m in MeOH) gewählt, die ein Zwischenprodukt der industriellen Synthese von l-Ascorbinsäure ist und daher leicht und kostengünstig verfügbar ist.…”