α-Halocarbonyls as a Valuable Functionalized Tertiary Alkyl Source

This review introduces the synthetic organic chemical value of α-bromocarbonyl compounds with tertiary carbons. This α-bromocarbonyl compound with a tertiary carbon has been used primarily only as a radical initiator in atom transfer radical polymerization (ATRP) reactions. However, with the recent development of photo-radical reactions (around 2010), research on the use of α-bromocarbonyl compounds as tertiary alkyl radical precursors became popular (around 2012). As more examples were reported, α-bromocarbonyl compounds were studied not only as radicals but also for their applications in organometallic and ionic reactions. That is, α-bromocarbonyl compounds act as nucleophiles as well as electrophiles. The carbonyl group of α-bromocarbonyl compounds is also attractive because it allows the skeleton to be converted after the reaction, and it is being applied to total synthesis. In our survey until 2022, α-bromocarbonyl compounds can be used to perform a full range of reactions necessary for organic synthesis, including multi-component reactions, cross-coupling, substitution, cyclization, rearrangement, stereospecific reactions, asymmetric reactions. α-Bromocarbonyl compounds have created a new trend in tertiary alkylation, which until then had limited reaction patterns in organic synthesis. This review focuses on how α-bromocarbonyl compounds can be used in synthetic organic chemistry.

Ring expansion and ring opening of 3-halooxindoles with N-alkoxycarbonyl-O-tosylhydroxylamines for divergent access to 4-aminoquinolin-2-ones and N-Cbz-N’-arylureas

The reaction of N-alkoxycarbonyl-O-tosylhydroxylamines with indol-2-ones in situ generated from 3-halooxindoles has been developed for divergently accessing 4-aminoquinolin-2-ones and N-Cbz-N’-arylureas in good to excellent yields.

KOH-mediated stereoselective alkylation of 3-bromooxindoles for the synthesis of 3,3′-disubstituted oxindoles with two contiguous all carbon quaternary centres

The stereoselective synthesis of 3,3′-disubstituted oxindoles having all-carbon quaternary stereocenters has been achieved using KOH as a base with an excellent diastereomeric ratio (98 : 2).

A Co(ii)-catalyzed asymmetric ring opening reaction of spiro-epoxyoxindoles with allylboron

A Co(ii)/BOX-catalyzed asymmetric allylation of spiroepoxyoxindoles was developed, which is the first stereoconvergent allylation of epoxides, yielding chiral oxindoles bearing quaternary stereocenters.

Advances in Stereoconvergent Catalysis from 2005 to 2015: Transition-Metal-Mediated Stereoablative Reactions, Dynamic Kinetic Resolutions, and Dynamic Kinetic Asymmetric Transformations

Stereoconvergent catalysis is an important subset of asymmetric synthesis that encompasses stereoablative transformations, dynamic kinetic resolutions, and dynamic kinetic asymmetric transformations. Initially, only enzymes were known to catalyze dynamic kinetic processes, but recently various synthetic catalysts have been developed. This Review summarizes major advances in nonenzymatic, transition-metal-promoted dynamic asymmetric transformations reported between 2005 and 2015.

Enantioconvergent catalysis

An enantioconvergent catalytic process has the potential to convert a racemic starting material to a single highly enantioenriched product with a maximum yield of 100%. Three mechanistically distinct approaches to effecting enantioconvergent catalysis are identified, and recent examples of each are highlighted. These processes are compared to related, non-enantioconvergent methods.