Catalytic Regiodivergent Kinetic Resolution of Allylic Epoxides:  A New Entry to Allylic and Homoallylic Alcohols with High Optical Purity

Abstract

A novel regiodivergent kinetic resolution of a series of allylic epoxides with alkylzinc reagents is described. Results demonstrate the potential of chiral copper-phosphoramidite catalysts for enantiomer differentiation of allylic epoxides, allowing a chiral catalyst-stereoregulated synthesis of cyclic allylic and homoallylic alcohols with high optical purities.

Simple Synthetic Transformations of Highly Enantio‐Enriched 4‐Alkyl‐2,5,7‐cyclooctatrienols into Functionalized Bicyclo[4.2.0]octa‐2,4‐dienes and 2,6‐Cyclooctadienones

“…From a synthetic point of view, the possibility to access previously unobtainable 4‐alkyl‐2,5,7‐cyclooctatrienols of type 4 allowed us to study their reactivity for the first time 14. We report here an improved preparation of 4‐alkyl‐2,5,7‐cyclooctatrienols of type 4 in the presence of the phosphoramidite ligand ( R , R,R )‐ 3 15. With this catalyst the enantioselective desymmetrization reaction of 1 can be performed on a gram scale with higher yields and enantioselectivities ( ee ⪖ 93%) than in our previous report (Scheme ) 11…”

Phosphoramidites: Privileged Ligands in Asymmetric Catalysis

“…Hence, this doubly selective reaction consisting of a regioselective addition and a kinetic resolution represents a remarkable and rare example of a stereodivergent and parallel kinetic resolution reac-tion. [205][206][207] In this transformation, the catalyst discriminates between the two enantiomers of the starting material 105 and selectively converts the enantiomers into two different products 106 and 107 under identical reaction conditions. Such a reaction is complementary to most kinetic resolution reactions, where only one of the two enantiomers of the starting material is converted, while the other remains unreacted (see Scheme 33).…”

Phosphoramidite: privilegierte Liganden in der asymmetrischen Katalyse

“…Diese doppelt selektive Reaktion aus einer regioselektiven Addition und einer kinetischen Racematspaltung ist ein bemerkenswertes und seltenes Beispiel für eine stereodivergente und parallele kinetische Spaltungsreaktion. [205][206][207] Bei dieser Umwandlung unterscheidet der Katalysator zwischen den beiden Enantiomeren der Ausgangsverbindung 105 und überführt sie selektiv unter identischen Reaktionsbedingungen in zwei unterschiedliche Produkte, 106 und 107. Eine solche Reaktion ergänzt die meisten kinetischen Racematspaltungen, bei denen nur eins der beiden Enantiomere der Ausgangsverbindung umgesetzt wird, das andere dagegen unverändert bleibt (vgl.…”