Two-photon excitable boron complex based on tridentate imidazo[1,5-]pyridine ligand for heavy-atom-free mitochondria-targeted photodynamic therapy.

We have synthesized a cyan fluorescent boron complex based on a tridentate imidazo[1,5-]pyridine ligand. The boron complex was found to have potential applications as not only a chiroptical material but also a heavy-atom-free mitochondria-targeted photosensitizer for cancer treatment.

Unexpected formation of poly-functionalized fulvenes by the reaction of a tetraaryl[5]cumulene with iodine.

Longer cumulenes have come to draw considerable attention due to their unique properties and reactivities, leading to various hydrocarbons. In this manuscript, we describe the reaction of tetrakis(-methoxyphenyl)[5]cumulene with iodine to afford poly-functionalized fulvenes unexpected migration of a terminal aryl ring under ambient conditions. The obtained iodinated fulvenes were utilized in Suzuki-Miyaura cross-coupling reactions affording penta- and fully-arylated fulvenes successfully.

Synthesis of D-π-A type benzothiazole-pyridinium salt composite and its application as photo-degradation agent for amyloid fibrils.

We have synthesized a cyan fluorescent benzothiazole-pyridinium salt composite based on D-π-A architecture. This salt was found to work as not only a two- and three-photon excitable fluorophore but also a degradation agent against amyloid fibrils under LED irradiation conditions.

Two- and three-photon excitable quaternized imidazo[1,2-]pyridines as mitochondrial imaging and potent cancer therapy agents.

We have synthesized a series of quaternized imidazo[1,2-a]pyridines in three steps from commercially available reagents. These compounds exhibit blue fluorescence emission at around 425 nm with good quantum yields. In addition, one specific compound was found to work as not only a two- and three-photon excitable mitochondria imaging agent, but also a therapeutic agent upon continuous irradiation conditions.

Fluorescent Imidazo[1,5-]pyridinium Salt for a Potential Cancer Therapy Agent.

,'-Dimethylated imidazo[1,5-]pyridinium salt having good water solubility and exhibiting fluorescence emission was found to work as not only a bioimaging agent but also a therapeutic agent under UVA-LED irradiation conditions. Because the continuous UVA-LED irradiation to HeLa cells stained by the synthesized salt resulted in the cell death due to the mitochondrial damage, the salt has a potential application as photodynamic therapy agent against tumor cells.

Involvement of Lipocalin-like CghA in Decalin-Forming Stereoselective Intramolecular [4+2] Cycloaddition.

Understanding enzymatic Diels-Alder (DA) reactions that can form complex natural product scaffolds is of considerable interest. Sch 210972 1, a potential anti-HIV fungal natural product, contains a decalin core that is proposed to form through a DA reaction. We identified the gene cluster responsible for the biosynthesis of 1 and heterologously reconstituted the biosynthetic pathway in Aspergillus nidulans to characterize the enzymes involved.

Diastereoselective photodimerization reactions of chromone-2-carboxamides to construct a C2-chiral scaffold.

Irradiation of three chromone-2-carboxamides with a chiral auxiliary resulted in diastereoselective formation of a C2-chiral anti-HH dimer scaffold. Selection of the solvent polarity and decreasing the temperature resulted in asymmetric induction with up to 84% diastereomeric excess (de).

Catalytic amide allylation of α-ketoesters: extremely high enantioselective synthesis of ester functionalised α-methylene-γ-butyrolactones.

This communication reports a significant breakthrough on the novel catalytic amide allylation to the acyclic α-ketoester systems, achieving satisfactorily high yields and extremely high levels of the asymmetric induction to allow for highly enantioselective synthesis of ester functionalised α-methylene-γ-butyrolactones.

Catalytic enantioselective amide allylation of isatins and its application in the synthesis of 2-oxindole derivatives spiro-fused to the α-methylene-γ-butyrolactone functionality.

This article is a full account of the work exploring the potential utility of catalytic enantioselective amide allylation of various isatins using indium-based chiral catalysts. A survey of various isatin substrates and NH-containing stannylated reagents revealed that the reaction has a remarkably wide scope to result in extremely high yields and enantioselectivities (up to >99 %, 99 % ee) of variously substituted homoallylic alcohols. Several mechanistic investigations demonstrated that the substrate-reagent hydrogen-bond interaction plays a critical role in the formation of the key transition states to result in enhanced catalytic reaction.

Cytochrome P450 as dimerization catalyst in diketopiperazine alkaloid biosynthesis.

As dimeric natural products frequently exhibit useful biological activities, identifying and understanding their mechanisms of dimerization is of great interest. One such compound is (−)-ditryptophenaline, isolated from Aspergillus flavus, which inhibits substance P receptor for potential analgesic and anti-inflammatory activity. Through targeted gene knockout in A.

Deracemization of axially chiral nicotinamides by dynamic salt formation with enantiopure dibenzoyltartaric acid (DBTA).

Dynamic atroposelective resolution of chiral salts derived from oily racemic nicotinamides and enantiopure dibenzoyltartaric acid (DBTA) was achieved by crystallization. The absolute structures of the axial chiral nicotinamides were determined by X-ray structural analysis. The chirality could be controlled by the selection of enantiopure DBTA as a chiral auxiliary.

Construction of spiro-fused 2-oxindole/α-methylene- γ-butyrolactone systems with extremely high enantioselectivity via indium-catalyzed amide allylation of N-methyl isatin.

A remarkably effective method allowing an extremely high enantioselective synthesis of the spiro-fused 2-oxindole/α-methylene-γ-butyrolactones is described. The key strategy lies in the use of indium-catalyzed asymmetric amide allylation of N-methyl isatin with functionalized allylstannanes, which can lead to the antineoplastic spirocyclic lactones in almost enantiopure forms.

Combinatorial generation of complexity by redox enzymes in the chaetoglobosin A biosynthesis.

Redox enzymes play a central role in generating structural complexity during natural product biosynthesis. In the postassembly tailoring steps, redox cascades can transform nascent chemical scaffolds into structurally complex final products. Chaetoglobosin A (1) is biosynthesized by a hybrid polyketide synthase-nonribosomal peptide synthetase.

Asymmetric transformation by dynamic crystallization of achiral succinimides.

Optically active materials could be generated by simple solidification of achiral materials without an external chiral source. When achiral cis-3,4-diphenylsuccinimides were solidified in the presence of a catalytic amount of DBU by evaporating the solvent with stirring, optically active trans-3,4-diphenylsuccinimides were obtained quantitatively with high enantiomeric excesses.

Total spontaneous resolution by deracemization of isoindolinones.

Separated: 3-hydroxy-3-phenylisoindolin-1-ones have been resolved by dynamic preferential crystallization. The compounds were effectively racemized through ring-opening and ring-closing reactions via achiral intermediates under basic conditions. Crystallization from a toluene solution containing 1,8-diazabicyclo[5.

Two-step asymmetric reaction using the frozen chirality generated by spontaneous crystallization.

N,N-diallyl-4-methyl-1-propyl-2-quinolone-3-carboxamide afforded chiral crystals of a P2(1) crystal system by spontaneous crystallization. The molecular chirality in the crystal was retained after the crystals were dissolved in a solvent at a low temperature, and the frozen molecular chirality was effectively transferred to the products by a two-step reaction involving hydrogenation and intermolecular photocycloaddition reactions.

Asymmetric intramolecular cyclobutane formation via photochemical reaction of N,N-diallyl-2-quinolone-3-carboxamide using a chiral crystalline environment.

Crystal structures and photochemical reactions of three N,N-diallyl-2-quinolone-3-carboxamides were investigated. One quinolonecarboxamide afforded chiral crystals of a P2(1) crystal system by spontaneous crystallization, and the molecular chirality in the crystal was effectively transferred to cyclobutane in 96% ee by an intramolecular 2 + 2 photocycloaddition reaction in the solid state.

Asymmetric photocycloaddition of naphthamide with a diene using the provisional molecular chirality in a chiral crystal.

N-(2-Methoxy-1-naphthoyl)piperidine afforded chiral crystals by spontaneous crystallization, and the molecular chirality of the crystals was retained after dissolving them in a cooled solvent. An asymmetric photocycloaddition reaction with a diene was performed using the provisional chiral molecular conformation derived from these chiral crystals.

Kinetic resolution of racemic amines using provisional molecular chirality generated by spontaneous crystallization.

N-(2-methoxy-1-naphthoyl)pyrrolidine afforded chiral crystals by spontaneous crystallization. The molecular chirality in the crystal was retained after dissolving the crystals in a cooled solvent. Kinetic resolution of racemic amines was performed using the provisional chiral molecular conformation derived from chiral crystals.

Exclusive photodimerization reactions of chromone-2-carboxylic esters depending on reaction media.

The irradiation of chromone-2-carboxylic esters resulted in the stereo- and regioselective formation of C(2) chiral anti-HH dimers from the triplet excited state. On the contrary, photolysis in the solid-state gave anti-HT dimers exclusively controlled by molecular arrangement in the crystal.

Generation and amplification of optical activity of axially chiral N-(1-naphthyl)-2(1H)-pyrimidinethione by crystallization.

X-Ray crystallographic analysis of N-(1-naphthyl)-2(1H)-pyrimidinethione revealed that the space group was tetragonal and chiral P4(3). The rate of racemization due to the C-N bond rotation was considerably influenced by the solvent properties. A nonpolar solvent lowers the ΔG(‡)value by about 3.