Carbene-Catalyzed Enantioselective Synthesis of γ-Keto-β-silyl Esters and Amides

Abstract

A variety of γ-keto-β-silyl esters and amides, most with extremely high enantioselectivities, were efficiently prepared via a carbene-catalyzed formal [4 + 2] annulation followed by ring opening with nucleophiles. The resulting compounds from this one-pot strategy can be easily converted into enantioenriched β,σ-dihydroxyl esters.

Enantioselective N-heterocyclic carbene-catalyzed rearrangement of enol ε-lactones

“…The Chi group demonstrated an array of enantioselective α-, β-, and γ-functionalization reactions of para -nitro phenyl esters. 14 Other activated esters, such as N -hydroxyphthalimide esters 15 and 1-hydroxybenzotriazole esters, 16 are also good substrates for NHC activation. In these reactions, the OR group of esters as leaving groups becomes atomic waste after NHC activation.…”

Desymmetrization of Cyclic 1,3-Diketones under N -Heterocyclic Carbene Organocatalysis: Access to Organofluorines with Multiple Stereogenic Centers

“…Given the significant success of asymmetric N-heterocyclic carbene (NHC) catalysis [43][44][45][46][47][48][49][50][51][52] and privileged structural characters of prochiral 1,3-diketones, based on our ongoing interest in organocatalysis [53][54][55][56][57], we envisioned that a versatile method for the synthesis of enantioenriched organofluorines with multiple stereogenic centers might be established based on NHC-catalyzed asymmetric desymmetrization of novel prochiral fluorinated or fluoromethylated oxindolyl 1,3-ketones. Notably, asymmetric synthesis of spirocycle compounds has attracted a lot of synthetic attention [58][59][60][61].…”

Solvent-free synthesis of enantioenriched β-silyl nitroalkanes under organocatalytic conditions

“…Metal-catalyzed reaction of various nucleophiles to β-silyl α,βunsaturated carbonyl compounds were documented as one of the straightforward and atom-economic approaches for the facile synthesis of chiral organosilanes (Scheme 1c-f) [30][31][32][33]. Recently, the aforementioned reaction under organocatalytic conditions has gained attention [34][35][36]. In this context, Huang, Fu and co-workers reported carbene-catalyzed enantioselective formal [4 + 2] annulation reactions of β-silyl enones with enals and with active acetic esters (Scheme 1g) for the preparation of chiral organosilanes [34][35][36].…”

“…Recently, the aforementioned reaction under organocatalytic conditions has gained attention [34][35][36]. In this context, Huang, Fu and co-workers reported carbene-catalyzed enantioselective formal [4 + 2] annulation reactions of β-silyl enones with enals and with active acetic esters (Scheme 1g) for the preparation of chiral organosilanes [34][35][36]. Very recently, during the final stage of our work, the same group disclosed an organocatalyzed conjugate addition of thiols to β-silyl enones for the synthesis of chiral α-mercaptosilanes (Scheme 1g) [36].…”