Catalytic asymmetric defluorinative allylation of silyl enol ethers

Merging Organocatalysis with 1,2-Boronate Rearrangement: A Lewis Base-Catalyzed Asymmetric Multicomponent Reaction

Catalytic asymmetric multicomponent 1,2-boronate rearrangements provide a practical approach for synthesizing highly valuable enantioenriched boronic esters. When applied to alkenyl or heteroaryl boronates, these reactions have relied mainly on transition-metal catalysis. Herein, we present an organocatalytic, Lewis base-catalyzed asymmetric multicomponent 1,2-boronate rearrangement, involving indoles, boronic esters, and Morita-Baylis-Hillman carbonates, leading to enantioenriched, highly substituted indole and indoline derivatives. Using cinchona alkaloid-based catalysts, high selectivity has been achieved, enabling expansion of the chemical space around pharmaceutically relevant indole and indoline derivatives.

Organocatalytic Asymmetric Allylic Benzylborylation via Fluoride-Assisted Catalytic Generation of α-Boryl Carbanionic Intermediates

Herein we describe the organocatalytic asymmetric allylic benzylborylation of allyl fluorides with α-silyl benzylboronic esters. The catalytic protocol leverages the singular features of fluoride as an unconventional leaving group, enabling the catalytic generation of reactive α-boryl carbanion species through desilylative activation. It allows the construction of a wide set of homoallylic benzylated organoboronates bearing two contiguous stereocenters. The chiral boronate installed in the products serves as a synthetic lynchpin to construct complex chemical architectures in a stereospecific manner.

Enantioselective Lewis base catalysed allylation of picoline- and quinaldine-based latent pronucleophiles

Picolines and quinaldines are valuable building blocks and intermediates in the synthesis of natural products and pharmaceuticals. Functionalization of the methyl group in picolines and quinaldines under mild conditions is challenging. We report that the concept of latent pronucleophiles enables Lewis base catalysed allylation of picolines and quinaldines with allylic fluorides starting from silylated picolines and quinaldines. Reactions afford enantioenriched allylation products when chiral Lewis base catalysts are used. The allylation products can be rapidly transformed to quinolizine-4-ones.

Regioconvergent Nucleophilic Substitutions with Morita-Baylis-Hillman Fluorides

Lithium iodide enables regioconvergent C-F bond functionalization of isomeric Morita-Baylis-Hillman fluorides with carbon, sulfur, and nitrogen nucleophiles. The defluorinative carbon-carbon and carbon-heteroatom bond formations give multifunctional compounds in excellent yields and with good to high diastereoselectivities at room temperature. The possibility of catalytic enantioselective allylation is also discussed.

Lewis-Base-Catalyzed N-Allylation of Silyl Carbamate Latent Pronucleophiles with Allylic Fluorides

Silyl carbamates, latent pronucleophile surrogates of carbamates, undergo allylation using allylic fluorides in the presence of common Lewis base catalysts. The reactions are rendered enantioselective in the presence of chiral Lewis base catalysts and produce suitably protected derivatives of enantioenriched chiral β-amino acids. The design of the latent pronucleophile featuring both a silyl group and an electron-deficient carbamate is instrumental in lowering the nucleophilicity of nitrogen and enabling enantioselective allylation in the presence of chiral cinchona alkaloid-based catalysts.