Highly Selective Preparation of a Chiral Quaternary Allyl Aryl Piperidinedione by Palladium-Catalyzed Asymmetric Allylation Under Solid-Liquid Phase-Transfer Catalysis

Simplifying Access to Targeted Protein Degraders via Nickel Electrocatalytic Cross-Coupling

C-C linked glutarimide-containing structures with direct utility in the preparation of cereblon-based degraders (PROTACs, CELMoDs) can be assessed in a single step from inexpensive, commercial α-bromoglutarimide through a unique Brønsted-acid assisted Ni-electrocatalytic approach. The reaction tolerates a broad array of functional groups that are historically problematic and can be applied to the simplified synthesis of dozens of known compounds that have only been procured through laborious, wasteful, multi-step sequences. The reaction is scalable in both batch and flow and features a trivial procedure wherein the most time-consuming aspect of reaction setup is weighing out the starting materials.

Enantioselective Copper-Catalyzed Intermolecular Cyanobenzoyldifluoromethylation of Alkenes: Access to Chiral β-Difluoroacyl Nitriles

A novel asymmetric copper-catalyzed intermolecular cyanobenzoyldifluoromethylation of alkenes with iododifluoromethyl ketones and TMSCN has been reported, which provides a particularly valuable route to access chiral β-difluoroacyl nitriles with excellent enantioselectivities. The method permits the efficient cyanation of varied β-difluoroacyl-benzylic radicals in mild conditions with high functional group tolerance. The reaction proceeds through a radical pathway. In order to get insight into the stereochemical outcome, computational mechanistic studies were conducted.

Construction of quaternary carbon centers by KOtBu-catalyzed α-homoallylic alkylation of lactams with 1,3-dienes

We report a KOtBu-catalyzed α-homoallylic alkylation of lactams with 1,3-dienes.

Reactions of Sodium Diisopropylamide: Liquid-Phase and Solid-Liquid Phase-Transfer Catalysis by N,N,N',N″,N″-Pentamethyldiethylenetriamine

Sodium diisopropylamide (NaDA) in N,N-dimethylethylamine (DMEA) and DMEA-hydrocarbon mixtures with added N,N,N',N″,N″-pentamethyldiethylenetriamine (PMDTA) reacts with alkyl halides, epoxides, hydrazones, arenes, alkenes, and allyl ethers. Comparisons of PMDTA with N,N,N',N'-tetramethylethylenediamine (TMEDA) accompanied by detailed rate and computational studies reveal the importance of the trifunctionality and κ2-κ3 hemilability. Rate studies show exclusively monomer-based reactions of 2-bromooctane, cyclooctene oxide, and dimethylresorcinol. Catalysis with 10 mol % PMDTA shows up to >30-fold accelerations (kcat > 300) with no evidence of inhibition over 10 turnovers. Solid-liquid phase-transfer catalysis (SLPTC) is explored as a means to optimize the catalysis as well as explore the merits of heterogeneous reaction conditions.

Transition Metal-Catalyzed α-Position Carbon–Carbon Bond Formations of Carbonyl Derivatives

α-Functionalization of carbonyl compounds in organic synthesis has traditionally been accomplished via classical enolate chemistry. As α-functionalized carbonyl moieties are ubiquitous in biologically and pharmaceutically valuable molecules, catalytic α-alkylations have been extensively studied, yielding a plethora of practical and efficient methodologies. Moreover, stereoselective carbon–carbon bond formation at the α-position of achiral carbonyl compounds has been achieved by using various transition metal–chiral ligand complexes. This review describes recent advances—in the last 20 years and especially focusing on the last 10 years—in transition metal-catalyzed α-alkylations of carbonyl compounds, such as aldehydes, ketones, imines, esters, and amides and in efficient carbon–carbon bond formations. Active catalytic species and ligand design are discussed, and mechanistic insights are presented. In addition, recently developed photo-redox catalytic systems for α-alkylations are described as a versatile synthetic tool for the synthesis of chiral carbonyl-bearing molecules.

Construction of Quaternary Carbon Center by Catalytic Asymmetric Alkylation of 3-Arylpiperidin-2-ones Under Phase-Transfer Conditions

A highly enantioselective synthesis of δ-lactams having a chiral quaternary carbon center at the α-position has been developed through an asymmetric alkylation of 3-arylpiperidin-2-ones under phase-transfer conditions. In this transformation, a 2,2-diarylvinyl group on the δ-lactam nitrogen atom plays a crucial role as a novel protecting group and an achiral auxiliary for improving both yield and enantioselectivity of the reaction.