Enzymatic resolution of secondary alcohols coupled with ruthenium-catalyzed racemization without hydrogen mediator

Asymmetric Transformations by Coupled Enzyme and Metal Catalysis: Dynamic Kinetic Resolution

“…We reported the use of an indenyl ruthenium complex 2 as a racemization catalyst which did not produce ketones as the byproducts [17] . The metal catalyst requires a weak base like triethylamine and molecular oxygen to be activated.…”

Lipase‐Catalyzed Domino Dynamic Kinetic Resolution of Racemic 3‐Vinylcyclohex‐2‐en‐1‐ols/Intramolecular Diels–Alder Reaction: One‐Pot Synthesis of Optically Active Polysubstituted Decalins

“…Recently, lipase-catalyzed dynamic kinetic resolution (DKR) has been developed to overcome this problem. [2] In this reaction the KR was accompanied by the simultaneous racemization of the slow-reacting enantiomers of the alcohols with ruthenium catalysts such as [RuCl(indenyl)(PPh 3 ) 2 ] (1 a), [3] [Ru 2 (CO) 4 (m-H)(C 4 Ph 4 COHOCC 4 Ph 4 )] (1 b), [4] [Ru(CO) 2 Cl(C 4 Ph 4 CNHCHMe 2 )] (1 c), [5] [{RuCl 2 (pcymene)} 2 ] (1 d), [6] and [Ru 2 Cl 2 (m-Cl)(m-H)(p-cymene) 2 ]…”

“…[2][3][4][5][6] Thus, the racemization of (S)-2 a (99 % ee) with 1 c in CH 2 Cl 2 at 25 8C was slow, [15] and that with 1 d provided an 11 % yield of the ketone 6 a after 6 h ( Figure 1). We found [{RuCl 2 (mesitylene)} 2 ]…”

One-pot synthesis of enantiopure syn -1,3-diacetates from racemic syn / anti mixtures of 1,3-diols by dynamic kinetic asymmetric transformation

“…In particular, lipases have emerged as efficient and robust biocatalysts that give good selectivities for a broad range of substrates (3, 4). The determination of the first crystal structure of lipases in 1990 (5, 6), preceded by a low-resolution crystal structure of a lipase from Geotrichum candidum in 1979 (7), and the observation that lipases work well in organic solvents (8-12) were factors that stimulated the development and use of these enzymes.More recently, the combination of enzymes and transition metals in coupled catalytic processes has attracted considerable attention (13)(14)(15)(16)(17)(18)(19)(20)(22)(23)(24)(25)(26)(27)(28)(29)(30). Simultaneous in situ racemization of the substrate by a transition metal and enzymatic resolution has resulted in efficient deracemization processes via so-called dynamic kinetic resolution (DKR).…”

“…In 1999 also, a Korean group (27) reported on the combination of a lipase and a ruthenium catalyst for DKR of secondary alcohols. Since then a large number of functionalized alcohols have been shown to undergo efficient DKR by combination of an enzyme and a ruthenium catalyst (18)(19)(20)(22)(23)(24)(25)(26)(27)(28)(29)(30).In the present work we applied the combined transition metal͞ enzyme system to the enantioselective synthesis of acyclic 1,3-diols. Stereoselective synthesis of acyclic 1,3-diols has attracted much attention, because these units occur as structural elements in a large number of polyketide natural products (31, 32) and polyene macrolide antibiotics (33, 34).…”