Stereoselective α-Hydroxylation of Amides Using Oppolzer's Sultam as Chiral Auxiliary

α-Hydroxylation of α,α-Disubstituted N-tert-Butanesulfinyl Ketimines with Molecular Oxygen: Stereoselective Synthesis of α-Tertiary Hydroxyimines

α-Tertiary hydroxyimines were stereoselectively synthesized from enantioenriched N-tert-butanesulfinyl ketimines using potassium tert-butoxide, molecular oxygen, and trimethyl phosphite. The stereoselective hydroxylation of acyclic ketimines bearing two sterically similar α-substituents was achieved by controlling the geometry of the metalloenamine intermediates and the facial selectivity of hydroxylation. The synthetic utility of the resulting α-tertiary hydroxyimines was demonstrated through the successful diastereoselective synthesis of highly substituted β-amino alcohols.

A Diastereoselective Route to Benzoannelated Bridged Sultams

A practical diastereoselective method for the synthesis of benzoannelated tri- and tetracyclic bridged sultams has been developed. The synthetic route employs widely available, substituted o-iodoanilines and is based on intramolecular Michael addition followed by cycloalkylation with α,ω-dihaloalkanes, or vice versa. The target compounds were isolated in good yields and the diastereoselectivity of the reaction could be easily controlled by the order of Michael addition and cycloalkylation steps.

A New Asymmetric Synthesis of (S)-14-Methyl-1-Octadecene, the Sex Pheromone of the Peach Leafminer Moth

An asymmetric synthesis of 14-methyl-1-octadecene, the sex pheromone of the peach leafminer moth, has been efficiently achieved. A key chiral intermediate, ( R)−4-(benzyloxy)−3-methylbutanal, which has been developed as the resource chemical, can be obtained in large quantities from the steroid industry. 1,11-Undecanediol is selectively masked, and then converted into a phosphonium salt derivative, thereby effectively constructing a carbon skeleton. The target molecule is synthesized in 8 linear steps, with a 42% yield. The key characteristic of our synthesis lies in its chiral-pool strategy.

Use of chiral auxiliaries in the asymmetric synthesis of biologically active compounds: A review

This review article describes the use of some of the most popular chiral auxiliaries in the asymmetric synthesis of biologically active compounds. Chiral auxiliaries derived from naturally occurring compounds, such as amino acids, carbohydrates, and terpenes, are considered essential tools for the construction of highly complex molecules. We highlight the auxiliaries of Evans, Corey, Yamada, Enders, Oppolzer, and Kunz, which led to remarkable progress in asymmetric synthesis in the last decades and continue to bring advances until the present day.

Palladium-catalyzed annulation of N-alkoxy benzsulfonamides with arynes by C–H functionalization: access to dibenzosultams

Palladium-catalyzed C–H/N–H functionalization of N-alkoxy benzsulfonamides with arynes provides dibenzosultams via C–C/C–N bond formation, accompanied by an unexpected N–O bond cleavage.

Synthesis of the Sex Pheromone of the Tea Tussock Moth Based on a Resource Chemistry Strategy

Synthesis of the sex pheromone of the tea tussock moth in 33% overall yield over 10 steps was achieved. Moreover, the chiral pool concept was applied in the asymmetric synthesis. The synthesis used a chemical available on a large-scale from recycling of wastewater from the steroid industry. The carbon skeleton was constructed using the C4+C5+C8 strategy. Based on this strategy, the original chiral center was totally retained.

Diastereoselective α-Hydroxylation of N-tert-Butanesulfinyl Imidates and N'-tert-Butanesulfinyl Amidines with Molecular Oxygen

Diastereoselective α-hydroxylation using molecular oxygen has been achieved with chiral α-alkyl N-tert-butanesulfinyl imidates and α-aryl N'-tert-butanesulfinyl amidines. The aza-enolates generated from deprotonation of imidates/amidines can be intercepted by O₂ with excellent diastereocontrol and subsequently transformed into α-hydroxylation products in the presence of the reductant trimethyl phosphite.

Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles

Chiral phase-transfer catalysis is one of the major catalytic principles in asymmetric catalysis. A broad variety of different catalysts and their use for challenging applications have been reported over the last decades. Besides asymmetric C–C bond forming reactions the use of chiral phase-transfer catalysts for enantioselective α-heterofunctionalization reactions of prochiral nucleophiles became one of the most important field of application of this catalytic principle. Based on several highly spectacular recent reports, we thus wish to discuss some of the most important achievements in this field within the context of this review.

N,N-Dimethylformamide (DMF) as a Source of Oxygen To Access α-Hydroxy Arones via the α-Hydroxylation of Arones

An unprecedented α-hydroxylation strategy was developed for the synthesis of α-hydroxy arones using N,N-dimethylformamide (DMF) as an oxygen source. Control experiments demonstrated that the oxygen atom of the hydroxy group in the α-hydroxy arones produced in this reaction was derived from DMF. This new reaction therefore not only provides an alternative strategy for the α-hydroxylation of arones but also highlights the possibility of using the inexpensive common solvent DMF as a source of oxygen in organic synthesis.