The effect of ring size on the photo-Favorskii induced ring-contraction reaction of the hydroxybenzocycloalkanonyl acetate and mesylate esters (7a-d, 8a-c) has provided new insight into the mechanism of the rearrangement. By monotonically decreasing the ring size in these cyclic derivatives, the increasing ring strain imposed on the formation of the elusive bicyclic spirocyclopropanone 20 results in a divergence away from rearrangement and toward solvolysis. Cycloalkanones of seven or eight carbons undergo a highly efficient photo-Favorskii rearrangement with ring contraction paralleling the photochemistry of p-hydroxyphenacyl esters. In contrast, the five-carbon ring does not rearrange but is diverted to the photosolvolysis channel avoiding the increased strain energy that would accompany the formation of the spirobicyclic ketone, the "Favorskii intermediate 20". The six-carbon analogue demonstrates the bifurcation in reaction channels, yielding a solvent-sensitive mixture of both. Employing a combination of time-resolved absorption measurements, quantum yield determinations, isotopic labeling, and solvent variation studies coupled with theoretical treatment, a more comprehensive mechanistic description of the rearrangement has emerged.

• MeSH
• cykloalkany chemie   MeSH
• estery MeSH
• fotochemie MeSH
• ketony chemie   MeSH
• kvantová teorie MeSH
• molekulární struktura MeSH
• rozpouštědla chemie   MeSH
• spirosloučeniny chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• cykloalkany MeSH
• estery MeSH
• ketony MeSH
• rozpouštědla MeSH
• spirosloučeniny MeSH

The rapid generation of molecular complexity from simple reactants is a key challenge in organic synthesis. Spiro compounds, underrepresented 3D motifs in chemical libraries, represent a challenge due to the creation of spiro quaternary carbon and the need to control the 3D shape in one step. Herein, we report the first ring contraction/formal [6 + 2] cycloaddition using synergistic Pd(0)/secondary amine catalysis, obtaining [5,5]-spiropyrazolone derivatives in excellent yields and stereoselectivities. We demonstrate that this reaction has a broad scope of early and late stage derivatization that will benefit the creation of highly valuable chemical libraries using spiropyrazolone motifs. We detected the key palladium activated intermediate in its protonated form by mass spectrometry and characterized its structure by infrared spectroscopy and DFT calculations, allowing us to propose a conceivable mechanistic pathway for this reaction.

• Publikační typ
• časopisecké články MeSH

We describe a triflic acid promoted cascade reaction of adamantane derivatives consisting of a decarboxylation of N-methyl protected cyclic carbamates and a subsequent intramolecular nucleophilic 1,2-alkyl shift to generate ring contracted iminium triflates. This reaction expands the family of similar transformations, such as Wagner-Meerwein-, Demjanov-Tiffeneau-, Meinwald- or (semi-)pinacol-rearrangement. It allows the preparation of noradamantane derivatives in a few steps, starting from simple hydroxy-substituted adamantane precursors.

• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

A case of distinctive benign cystadenoma of the parotid gland composed of several different morphological components is presented. The most conspicuous morphological component and the largest part of the neoplasm was represented by solid sheets of oncocytic cells surrounded by myoepithelial cell layer. Most oncocytic cells possessed large intracytoplasmic vacuoles with the nuclei displaced towards the periphery, imparting them with a striking signet-ring cell appearance. The size of the intracytoplasmic vacuoles ranged from 4 to 50 microm. Immunohistochemically these signet-ring cells lacked immunoreactivity for S-100 protein and cytokeratin but they strongly stained for antimitochondrial antibody 113-1. The present case illustrates an unusual, hitherto undescribed, morphological feature of benign oncocytic cystadenoma of the parotid gland.

• MeSH
• aktiny metabolismus   MeSH
• cystadenom metabolismus   patologie   chirurgie   MeSH
• imunoenzymatické techniky MeSH
• karcinom z prstenčitých buněk metabolismus   patologie   chirurgie   MeSH
• keratiny metabolismus   MeSH
• lidé MeSH
• mitochondrie imunologie   MeSH
• nádory příušní žlázy metabolismus   patologie   chirurgie   MeSH
• oxyfilní adenom metabolismus   patologie   chirurgie   MeSH
• proteiny S100 metabolismus   MeSH
• senioři MeSH
• vakuoly patologie   MeSH
• Check Tag
• lidé MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• Názvy látek
• aktiny MeSH
• keratiny MeSH
• proteiny S100 MeSH

We report a protocol for the one-pot two-step synthesis of noradamantane methylene amines. The first step is the triflic acid-promoted decarboxylation of adamantane carbamates, which causes rearrangement of the adamantane framework to form noradamantane iminium salts, which are reduced to amines in the second separate step.

• Publikační typ
• časopisecké články MeSH

We report an efficient synthesis of 4H-benzo[b][1,4]thiazine 1,1-dioxides via unprecedented ring contraction of 2,5-dihydrobenzo[f][1,2,5]thiadiazepine 1,1-dioxides under mild conditions involving carbon-sulfur bond formation. 2,5-Dihydrobenzo[f][1,2,5]thiadiazepine 1,1-dioxides are easily accessible from commercially available building blocks, including Fmoc-protected amino acids, 2-nitrobenzenesulfonyl chlorides, and bromo ketones. Benzothiazine 1,1-dioxides represent pharmacologically relevant derivatives with biological, medicinal, and industrial applications.

• MeSH
• benzodiazepinony chemie   MeSH
• epoxidové sloučeniny chemie   MeSH
• nitrobenzeny chemie   MeSH
• thiadiaziny chemie   MeSH
• thiaziny chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 2-nitrobenzenesulfenyl chloride MeSH Prohlížeč
• benzodiazepinony MeSH
• epoxidové sloučeniny MeSH
• nitrobenzeny MeSH
• thiadiaziny MeSH
• thiaziny MeSH

Ring contraction of 3-hydroxy-2,4(1H,3H)-quinolinediones (1) in aqueous potassium hydroxide resulted in the formation of 2-hydroxyindoxyls and/or dioxindoles. The choice of N-substituent and the reaction conditions govern the chemoselectivity of the reaction. N-Phenyl-substituted derivatives 1 give 2-hydroxyindoxyls, while N-alkyl- and N-benzyl-substituted derivatives afford the corresponding dioxindols. On the basis of byproduct analysis, as well as independent experiments, the most plausible reaction mechanism is proposed.

• MeSH
• alkálie chemie   MeSH
• biologické faktory chemická syntéza   MeSH
• chinoliny chemická syntéza   MeSH
• indoly chemická syntéza   MeSH
• voda chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• alkálie MeSH
• biologické faktory MeSH
• chinoliny MeSH
• indoly MeSH
• indoxyl MeSH Prohlížeč
• voda MeSH

Novel water-soluble dihydroxophosphorus(V) complexes of sulphophenyl substituted porphyrazine (6), corrolazine (7) and its pyrazine fused derivative (8) were prepared and their spectral, acid-base and photophysical properties in aqueous solutions were studied. Due to the presence of eight SO3H groups, the compounds were fully monomeric (7 and 8) or only slightly aggregated (6) in water. Spectrophotometric titration revealed that the two stage deprotonation of axially bonded hydroxy groups can be achieved for porphyrazine 6 (pKa1 = 5.62, pKa2 = 9.13) and pyrazine fused corrolazine 8 (pKa1 = 6.5, pKa2 = 11.7), while only the first dissociation stage could be observed for corrolazine 7 (pKa1 = 9.94). The fluorescence emission of the corrolazines 7, 8 and especially porphyrazine 6 was low in water (ΦF = 0.086, 0.18, and 0.014, respectively) and completely quenched under basic conditions due to photoinduced electron transfer. In comparison with porphyrazine 6, the contraction of the macrocycle in the corrolazines 7 and 8 induced significant improvement of singlet oxygen production in water reaching values of ΦΔ = 0.56 and 0.43, respectively, which makes the corrolazines promising photosensitizers for photodynamic therapy. The observed evolution of the electronic absorption spectra and fluorescence quenching observed in a basic medium was explained using the model DFT calculations (cc-pvtz basis set) performed for the dihydroxophosphorus(V) complexes of unsubstituted porphyrazine and corrolazine and their mono- and doubly deprotonated forms.

• Publikační typ
• časopisecké články MeSH

This review summarizes achievements in the synthesis of 1,2-disubstituted adamantane derivatives by the construction of the tricyclic framework either by total synthesis or by ring expansion/contraction reactions of corresponding adamantane homologues. It is intended to complement reviews focusing on the preparation of 1,2-disubstituted derivatives by C-H functionalization methods.

• Klíčová slova
• adamantane, alkyl shifts, diamondoids, homoadamantane, noradamantane, protoadamantane, rearrangement, ring contraction, ring expansion, total synthesis,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

BACKGROUND: Hyaluronan (HA) plays an important role in the repair of damaged skin and has been used for the treatment of wounds. Iodine is a mild topical antiseptic. AIM: A mixture of high molecular weight HA with the iodine complex KI(3) (hyiodine) was reported to accelerate wound healing in patients with diabetes and patients after surgery. We investigated how this mixture affects wound contraction, granulation tissue (GT) and wound edges in excision skin wounds in rats. METHODS: Hyiodine was applied to full-thickness wounds made on the back of rats. The areas of the contracting wounds were calculated from digital photographs. The moving edges of the wound were studied by histological methods. The properties of GT were studied in wounds in which contraction was prevented by the insertion of plastic rings. The effects of hyiodine were compared with those of high molecular weight (1200 kDa) HA, low molecular weight (11 kDa) HA and KI(3) solution. RESULTS: Hyiodine accelerated wound contraction significantly in the first 5 days of healing. On day 3, hyiodine-treated wounds had reduced to 63% of the original area, whereas the wound area in saline-treated animals was 75% of the original size. The proliferating epidermis was thicker in hyiodine-treated animals on day 7. In the wounds with inserted rings, hyiodine caused little change in GT, but the weight of the crust/exudate formed on the top of the wound was increased by 351% compared with only minor changes caused by the hyiodine components alone. CONCLUSIONS: Hyiodine supports wound healing by stimulating wound contraction and epidermal proliferation and by keeping the wound moist through increased exudation.

• MeSH
• epidermis účinky léků   patologie   MeSH
• exprese genu MeSH
• exsudáty a transsudáty účinky léků   metabolismus   MeSH
• granulační tkáň účinky léků   patologie   MeSH
• hojení ran účinky léků   fyziologie   MeSH
• jod farmakologie   MeSH
• kontraktura chemicky indukované   patologie   MeSH
• krysa rodu Rattus MeSH
• kůže účinky léků   zranění   patologie   MeSH
• kyselina hyaluronová farmakologie   MeSH
• kyseliny uronové metabolismus   MeSH
• preklinické hodnocení léčiv metody   MeSH
• proteiny metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• hyaluronan-iodine complex MeSH Prohlížeč
• jod MeSH
• kyselina hyaluronová MeSH
• kyseliny uronové MeSH
• proteiny MeSH