Simultaneous Stereoinvertive and Stereoselective C(sp3)-C(sp3) Cross-Coupling of Boronic Esters and Allylic Carbonates.

With increasing interest in constructing more three-dimensional entities, there has been growing interest in cross-coupling reactions that forge C(sp3)-C(sp3) bonds, which leads to additional challenges as it is not just a more difficult bond to construct but issues of stereocontrol also arise. Herein, we report the stereocontrolled cross-coupling of enantioenriched boronic esters with racemic allylic carbonates enabled by iridium catalysis, leading to the formation of C(sp3)-C(sp3) bonds with single or vicinal stereogenic centers. The method shows broad substrate scope, enabling primary, secondary, and even tertiary boronic esters to be employed, and can be used to prepare any of the four possible stereoisomers of a coupled product with vicinal chiral centers. The new method, which combines the simultaneous enantiospecific reaction of a chiral nucleophile with the enantioselective reaction of a chiral electrophile in a single process, offers a solution for stereodivergent cross-coupling of two C(sp3) fragments.

Iridium-Catalyzed Asymmetric Difunctionalization of C-C σ-Bonds Enabled by Ring-Strained Boronate Complexes.

Enantioenriched organoboron intermediates are important building blocks in organic synthesis and drug discovery. Recently, transition metal-catalyzed enantioselective 1,2-metalate rearrangements of alkenylboronates have emerged as an attractive protocol to access these valuable reagents by installing two different carbon fragments across C═C π-bonds. Herein, we report the development of an iridium-catalyzed asymmetric allylation-induced 1,2-metalate rearrangement of bicyclo[1.1.0]butyl (BCB) boronate complexes enabled by strain release, which allows asymmetric difunctionalization of C-C σ-bonds, including dicarbonation and carboboration. This protocol provides a variety of enantioenriched three-dimensional 1,1,3-trisubstituted cyclobutane products bearing a boronic ester that can be readily derivatized. Notably, the reaction gives trans diastereoisomers that result from an anti-addition across the C-C σ-bond, which is in contrast to the syn-additions observed for reactions promoted by PdII-aryl complexes and other electrophiles in our previous works. The diastereoselectivity has been rationalized based on a combination of experimental data and density functional theory calculations, which suggest that the BCB boronate complexes are highly nucleophilic and react via early transition states with low activation barriers.

An indoor location-based hospital Porter management system and trace analysis.

Porters play an important role in supporting hospital operations. Their responsibilities include transporting patients and medical equipment between wards and departments. They also need to deliver specimens, drugs, and patients' notes to the correct place at the right time. Therefore, maintaining a trustworthy and reliable porter team is crucial for hospitals to ensure the quality of patient care and smooth the flow of daily operations. However, most existing porter systems lack detailed information about the porter movement process. For example, the location of porters is not transparent to the dispatch center. Thus, the dispatcher does not know if porters are spending all their time providing services. The invisibility makes it difficult for hospitals to assess and improve the efficiency of porter operations. In this work, we first developed an indoor location-based porter management system (LOPS) on top of the infrastructure of indoor positioning services in the hospital National Taiwan University Hospital YunLin Branch. The LOPS provides real-time location information of porters for the dispatcher to prioritize tasks and manage assignments. We then conducted a 5-month field trial to collect porters' traces. Finally, a series of quantitative analyses were performed to assess the efficiency of porter operations, such as the movement distribution of porters in different time periods and areas, workload distribution among porters, and possible bottlenecks of delivering services. Based on the analysis results, recommendations were given to improve the efficiency of the porter team.

Dearomative Arylcyanation of Indoles via C-CN Bond Activation Enabled by Ni/Lewis Acid Cooperative Catalysis.

A nickel/Lewis acid cooperatively catalyzed intramolecular dearomative arylcyanation of indoles is presented. The reaction proceeds through a C-CN bond activation, dearomatization, and benzylic cyanation sequence, affording 3-cyano fused indolinyl heterocycles in good to excellent yields and excellent diastereoselectivity. The asymmetric version of the reaction can be established in moderate enantioselectivity by using a chiral ligand.

Chiral-Anion-Mediated Asymmetric Heck-Matsuda Reaction of Acyclic Alkenyl Alcohols.

Acyclic internal alkenes are a class of challenging substrates in asymmetric Heck-type reactions due to difficulties related to both reactivity and selectivity control. Employing acyclic alkenyl alcohols, an asymmetric Heck-Matsuda reaction is developed through the strategy of chiral anion phase transfer. Various chiral ketones could be obtained in high levels of enantioselectivity. A catalytic amount of dimethyl sulfoxide (DMSO) as an additive is crucial for the reaction to suppress the palladium-hydride-mediated side reactions.

Access to chiral tetrahydrofluorenes through a palladium-catalyzed enantioselective tandem intramolecular Heck/Tsuji-Trost reaction.

A palladium-catalyzed enantioselective coupling of 2,5-cyclohexadienyl-substituted aryl iodides and carbon or heteroatom nucleophiles is described. The reaction proceeded via a tandem asymmetric Heck insertion and Tsuji-Trost allylation, enabling the rapid construction of valuable chiral tetrahydrofluorenes by using a chiral H8-BINOL-based phosphoramidite ligand.

Pd(II)-Catalyzed Asymmetric Oxidative Annulation of N-Alkoxyheteroaryl Amides and 1,3-Dienes.

The first Pd(II)-catalyzed asymmetric oxidative annulation of N-alkoxyaryl amides and 1,3-dienes is reported, which features particular applicability for quick assembly of different types of chiral heterocycles with high yields and enantioselectivities. A novel chiral pyridine-oxazoline bearing a methoxyl group at the C-5 position and a gem-dimethyl group on the oxazoline moiety was found to be crucial for conversion.

Palladium-Catalyzed Asymmetric Aminohydroxylation of 1,3-Dienes.

A PdII -catalyzed asymmetric aminohydroxylation of 1,3-dienes with N-tosyl-2-aminophenols was developed by making use of a chiral pyridinebis(oxazoline) ligand. The highly regioselective reaction provides direct and efficient access to chiral 3,4-dihydro-2H-1,4-benzoxazines in high yield and enantioselectivity (up to 96:4 e.r.). The reaction employs readily available N-tosyl-2-aminophenols as a unique aminohydroxylation reagent and is complementary to known asymmetric aminohydroxylation methods.

Catalytic Enantioselective Assembly of Homoallylic Alcohols from Dienes, Aryldiazonium Salts, and Aldehydes.

A highly selective multicomponent carbonyl allylation reaction of 1,3-butadienes, aryldiazonium tetrafluoroborates, and aldehydes has been established under the combined catalysis of palladium acetate and chiral anion phase transfer to render the favorable assembly of chiral Z-configured homoallylic alcohols in high yields and with excellent levels of enantioselectivity.

Gold-catalyzed 6-exo-dig cycloisomerization: a versatile approach to functionalized phenanthrenes.

A novel gold-catalyzed 6-exo-dig cycloisomerization of o-propargylbiaryls has been developed that provides ready access to functionalized phenanthrenes in largely good to excellent yields. Notable features of this method are readily available starting materials, mild reaction conditions, and broad substrate scope.