Development of ProPhenol/Ti(IV) Catalyst for Asymmetric Hydroxylative Dearomatization of Naphthols.

By development of ProPhenol/Ti(IV) catalysts, a catalytic enantioselective hydroxylative dearomatization of naphthols is achieved by using TBHP as a simple oxidative reagent. The side coordinative chain equipped on the C1-position of ß-naphthols plays an important role for initiating this asymmetric hydroxylative reaction, which might be a result of the proper cocoordination effects to the titanium center in the catalyst. A reasonable catalytic cycle is proposed, the catalytic system is applied to a reasonable range of this type of phenolic compound, and related concise transformations are carried out.

Catalytic Asymmetric Reactions of α-Isocyanoacetates and meso-Aziridines Mediated by an in-Situ-Generated Magnesium Catalytic Method.

A catalytic asymmetric ring-opening reaction between α-isocyanoacetates and meso-aziridines has been realized by developing an in-situ-generated magnesium catalytic method. Chiral oxazoline-OH ligands were employed in the magnesium catalyst and diphenylphosphinamide was improved as a powerful achiral additive in this reaction. The ring-opening products of the desired reaction were obtained in good chemical yields and enantioselectivities. Moreover, these enantio-enriched adducts can be smoothly transformed into tetrahydropyrimidines mediated by a silver salt under mild conditions.

Catalytic asymmetric multiple dearomatizations of phenols enabled by a cascade 1,8-addition and Diels-Alder reaction.

A direct catalytic asymmetric multiple dearomatization reaction of phenols was disclosed, which provides expedient access to a series of architecturally complex polycyclic compounds bearing four stereogenic centers in high enantiopurity. The key to achieve such a transformation is the combination of a dearomative 1,8-addition of ß-naphthols to para-quinone methides generated in situ from propargylic alcohols and a subsequent intramolecular dearomative Diels-Alder reaction. Noteworthily, this protocol enrichs not only the diversity of dearomatized products but also the toolbox of dearomatization strategies.

Direct Synthesis of a Dioxabenzobicyclo[3.2.1]octane Core from Salicylaldehydes.

A copper(II) trifluoromethanesulfonate via Prins reaction between salicylaldehydes and allyl alcohols is realized under mild conditions. A series of compounds containing dioxabenzobicyclo[3.2.1]octane motifs are obtained in moderate to good yields. The current method can efficiently construct the valuable structural motif from easily accessed starting materials, providing a smooth method to build benzobicyclo skeletons.

The Important Role of the Byproduct Triphenylphosphine Oxide in the Magnesium(II)-Catalyzed Enantioselective Reaction of Hemiacetals and Phosphorus Ylides.

By employing a simple in situ generated magnesium catalyst, a direct asymmetric reaction between hemiacetals and phosphorus ylides was achieved through a tandem Wittig-oxa-Michael reaction sequence. Enantioenriched chromans, isochromans, and tetrahydropyrans were obtained in good chemical yields, and (-)-erythrococcamide B was synthesized in enantioenriched form. The byproduct triphenylphosphine oxide was identified as a necessary additive for this process.