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Isochromans are valuable building blocks for the synthesis of natural products and bioactive compounds. Herein, we report a diastereoselective halo‐cycloacetalization of olefinic aldehydes and alcohols using N‐haloamides as the halogenating agents. The reaction conditions are mild and can be operated in the absence of external catalysts. Olefinic aldehydes bearing different substituents and various alcohols are compatible with the reaction protocol, giving isochroman derivatives efficiently. [ABSTRACT FROM AUTHOR]

The optimization and modulation of the properties of photochromic compounds, such as their activation wavelengths and thermal relaxation half‐lives (τ1/2), are essential for their adaptation in various applications. In this work, we studied the effect of co‐planarization of the rotary fragment of two photochromic hydrazones with the core of the molecule on their switching properties. The Z and E isomers of both compounds exhibit red‐shifted absorption bands relative to their twisted versions, allowing for their photoswitching using longer wavelengths of light. Additionally, the thermal half‐lives of both hydrazones are drastically shortened from hundreds of years to days. [ABSTRACT FROM AUTHOR]

Trimethylsilyl triflate (TMSOTf) can be efficiently used for the synthesis of isochromans via Pictet-Spengler type reaction of vinylogous esters in good yields. The methodology is applied for the formal synthesis of key intermediate alcohols for the synthesis of D4 antagonist sonepiprazole (±)-U-101387 and the isochroman (±)-U-54537. [ABSTRACT FROM AUTHOR]

Six new compounds, colletobredins A–D (1–4) and colletomelleins A and B (5 and 6), along with 12 previously identified compounds, were isolated from the culture broth of Colletotrichum aotearoa BCRC 09F0161, a fungal endophyte residing in the leaves of an endemic Formosan plant Bredia oldhamii Hook. f. (Melastomataceae). The structures of the new compounds were established by spectroscopic methods, including UV, IR, HR-ESIMS and extensive 1D and 2D NMR techniques. The effects of some isolates on the inhibition of nitric oxide (NO) production in lipopolysaccharide-activated murine macrophage RAW264.7 cells were evaluated. All these compounds inhibited NO production in activated macrophages without any cytotoxicity at a concentration of 100 μM. Of these isolates, 1 showed weak NO inhibitory activity with IC50 value of 182.2 μM. To the best of our knowledge, this is the first report on isochroman glycoside metabolites (1–4) from the genus Colletotrichum. [ABSTRACT FROM AUTHOR]

A base-catalyzed ring-opening of 1-benzylisochromans 1 firstly produced 2-alkenylstilbenes 2, which then underwent a mild acid-catalyzed intramolecular cyclization to furnish 1,2-disubstituted indenes 3 in high yields. Subsequently, a base-catalyzed isomerization of the 1,2-disubstituted indenes 3 afforded the more stable 2,3-disubstituted indenes 4 in almost quantitative yields. [ABSTRACT FROM AUTHOR]

An unprecedented C–S formation protocol via the direct oxidative C(sp3)–H bond thioesterification of isochroman under metal-free conditions was developd. A series of isochroman derivatives could be afforded efficiently by the green, simple, and atom-economical method. [ABSTRACT FROM AUTHOR]

A new isochroman derivative, erythro-2-methyl-5-hydroxyphenylpropane-7,8-diol ( 1), and three known compounds including of (4S)-4,8-dihydroxy-3,4-dihydro-1(2H)-naphthalen-1-one ( 2), (4S)-4,6,8-trihydroxy-3,4-dihydro-1(2H)-naphthalen-1-one ( 3), and chrysogeside D ( 4), were isolated from Microsphaeropsis arundinis. Compounds 3 and 4 were first found in Microsphaeropsis. The antibacterial, antiphytopathogenic, and antioxidant activities of these compounds were evaluated. Compounds 1 and 4 inhibited Alternaria tenuissima, a pathogenic fungus causing root rot of Panax notoginseng with MICs at 64 μg/mL, which showed the ecological function of the endophyte for its host plant. [ABSTRACT FROM AUTHOR]

Indoor exposure to the spores and mycelial fragments of fungi that grow on damp building materials can result in increased non-atopic asthma and upper respiratory disease. The mechanism appears to involve exposure to low doses of fungal metabolites. Penicillium corylophilum is surprisingly common in damp buildings in USA, Canada and western Europe. We examined isolates of P. corylophilum geographically distributed across Canada in the first comprehensive study of secondary metabolites of this fungus. The sesquiterpene phomenone, the meroterpenoids citreohybridonol and andrastin A, koninginin A, E and G, three new alpha pyrones and four new isochromans were identified from extracts of culture filtrates. This is the first report of koninginins, meroterpenoids and alpha pyrones from P. corylophilum. These secondary metabolite data support the removal of P. corylophilum from Penicillium section Citrina and suggest that further taxonomic studies are required on this species. [ABSTRACT FROM AUTHOR]

A direct C(sp³)-H amination reaction of isochroman derivatives with arylamines was developed in the presence of iron(II) salt. A variety of isochroman derivatives and primary amines were selectively transformed into the corresponding oxidative coupling products in good to excellent yield under mild conditions [ABSTRACT FROM AUTHOR]

An efficient, stereo- and regioselective palladium-catalyzed 6-exo-dig intramolecular hydroarylation of propargyl ethers which provides a concise access to functionalized isochromans in high yields has been developed. A wide range of substrates possessing aromatic, aliphatic and heteroaromatic alkynes can be efficiently transformed into the targeted isochromans. Irrespective of the nature of the substrates, the cyclization follows highly selective stereo- and regiochemistry. [ABSTRACT FROM AUTHOR]

The oxa-Pictet-Spengler reaction with various aldehydes and β-arylethanol yields 1-substituted-isochromans in the presence of bismuth triflate as catalyst in good yields. The method was extended to O,O-acetals to afford the corresponding 1,1-disubstituted-isochromans in good yields. These studies also provide insights into the catalytic role of triflic acid generated upon hydrolysis of Bi(OTf)3 by residual water. The low toxicity and easy handling of Bi(OTf)3 by comparison with triflic acid make these procedures an attractive method to provide isochromans in good to excellent yields. [ABSTRACT FROM AUTHOR]

A new isochroman, 6-hydroxy-3-methylisochroman-5-carboxylic acid, and six known compounds were isolated from the culture of marine-derived mangrove fungus 1893#. Their structures were elucidated by analysis of spectroscopic data. [ABSTRACT FROM AUTHOR]

Supported catalysts are important tools for developing green-economy-based processes. Palladium nanoparticles (NPs) that are immobilized on two fibers developed as metal scavengers (i.e., Smopex®-234 and Smopex®-111, 1% w/w) have been prepared and tested in copper-free cyclocarbonylative Sonogashira reactions. Their catalytic activity has been compared with that of a homogeneous catalyst (i.e., PdCl2(PPh3)2). Pd/Smopex®-234 showed high activity and selectivity in the synthesis of functionalized heterocycles, such as phthalans and isochromans, even when working with a very low amount of palladium (0.2–0.5 mol%). The extension of Pd/Smopex®-234 promoted cyclocarbonylative reactions to propargyl and homopropargyl amides afforded the corresponding isoindoline and dihydrobenzazepine derivatives. A preliminary test on Pd NPs leaching into the solution (1.7 × 10−3 mg) seems to indicate that, at the end of the reaction, almost all of the active metal is present on the fiber surface. [ABSTRACT FROM AUTHOR]