Synthesis Of Isochromans Research Articles

Palladium mediated domino reaction: synthesis of isochromenes under aqueous medium.

Isochromenes have been synthesized using palladium-catalyzed C–C and C–O bond forming reactions starting from ortho-bromo tertiary benzylic alcohols and internal acetylenes. Notably, this domino process is feasible by using the green solvent, water. The protocol exhibited a broad substrate scope and afforded various isochromenes.

Synthesis of Isochroman Derivatives via Oxa-Pictet–Spengler Reaction of Vinylogous Esters

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 D 4 antagonist sonepiprazole (±)-U-101387 and the isochroman (±)-U-54537.

ChemInform Abstract: Synthesis of Isochromene and Related Derivatives by Rhodium‐Catalyzed Oxidative Coupling of Benzyl and Allyl Alcohols with Alkynes.

AbstractIt provides a straightforward method to prepare isochromenes and related compounds.

ChemInform Abstract: Synthesis of Isochromans by Hydriodic Acid or Iodine Mediated Cyclization Reactions of 1‐(2‐Vinylphenyl)propan‐2‐ols.

AbstractSimple routes to the title compounds (IV), (V), and (VII) are presented by using readily available starting materials and hydriodic acid or iodine mediated cyclizations.

Synthesis of Isochromans by Palladium-Catalyzed C-H Olefination

The synthesis of isochromans 3 from tertiary alcohols 1 and alkenes 2 via a palladium-catalyzed hydroxyl-directed C-H olefination-intramolecular oxidative cyclization sequence is described. Optimization of the reaction conditions showed that the amino acid ligand shown is critical for high conversion. Instructively, hexafluoro­benzene is preferred to toluene to avoid competing olefination of the solvent. In general, yields were higher with electron-rich arenes (R¹ = Me, OMe) compared to electron-poor ones (R¹ = Hal, CF3). The EWG on the alkene is required since only the uncyclized olefins 4 were isolated with electron-neutral alkenes (R4 = alkyl, aryl). The methodology was extended to secondary and primary alcohols (5-8), although the yields were somewhat low due to competing decomposition of the starting materials.

Synthesis of Isochromans by Hydriodic Acid or Iodine Mediated Cyclization Reactions of 1-(2-Vinylphenyl)propan-2-ols

Treatment of 1-(2-vinylphenyl)propan-2-ols, which can be easily prepared from 2-bromostyrenes and epoxides, with hydriodic acid in acetonitrile yields the corresponding isochromans (1H-3,4-dihydro-2-benzopyrans). When the above alcohols are treated with iodine in acetonitrile in the presence of sodium hydrogencarbonate, the corresponding 1-iodomethylisochromans are obtained, which can be easily converted into the corresponding 1-alkyl(or aryl)sulfanylmethylisochromans on treatment with sodium thiolates in DMF.

First Synthesis of Dimethyl-1H-Isochromeno[3,4-b]Carbazoles

The first synthesis of isochromene fused carbazols, (4aS, 13bR)-2,5,5-trimethyl-3,4,4a,5,8,13b-hexahydroisochromeno[3,4-b]carbazole (2) and its epi-isomer 3 by condensation of citral and 2-hydroxycarbazole using Ti(OEt)4 and MeAlC12 as catalysts is described.

ChemInform Abstract: Synthesis of Isochromanes (IV) and Isothiochromanes (VII) Bearing Fluorinated One‐Carbon Units via Intramolecular Cyclizations of ortho‐Substituted α‐(Trifluoromethyl)styrenes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis of Isochromanes and Isothiochromanes Bearing Fluorinated One-Carbon Units via Intramolecular Cyclizations of ortho-Substituted α-(Trifluoromethyl)styrenes

α-(Trifluoromethyl)styrenes bearing a nucleophilic oxygen or sulfur atom tethered by a methylene or methyne unit at the ortho carbon were prepared by the coupling reaction of 2-bromo-3,3,3-trifluoropropene with aryl iodides via (3,3,3-trifluoroprop-1-en-2-yl)boronic acid. The styrenes thus obtained readily undergo an intramolecular nucleophilic addition or substitution (SN2'-type) of the oxygen and sulfur under basic conditions, leading to 4-trifluoromethyl- or 4-difluoromethylene-substituted isochromanes and isothiochromanes, respectively.

Carboxylate-Directed Kumada Coupling of an Acetaldehyde Synthon with 2-Bromobenzoates Used towards the Synthesis of Isochromanes

This letter describes the Kumada coupling of bromobenzoic acid derivatives with the acetaldehyde enolate synthon (1,3-dioxolan-2-ylinethyl)magnesium bromide. The lithium carboxylate salt shows the highest reactivity in the coupling reaction while addition of t-BuOLi affords optimal selectivity. During this work. we have observed a strong directing effect of the sodium carboxylate function which can be useful in differentiating electronically similar diaryl bromides.

The synthesis of isochroman-4-ols and isochroman-3-ols: models for naturally occurring benzo[ g]isochromanols

The synthesis of isochromanes containing hydroxy substituents at the 4- and 3-positions has been achieved. The key step for the synthesis of the isochroman-4-ols entailed an oxidative mercury mediated ring closure of 2-(prop-1-enyl)phenylmethanol derivatives, while in the synthesis of the isochroman-3-ols the key step involved ozonolysis of 2-(prop-2-enyl)phenylmethanol derivatives.

Synthesis of isochromans via the titanium tetrachloride assisted cyclization of acetals of phenethyl alcohols

This paper reports the preparation of five 3,4-dihydro-1 H -2-benzopyrans in good yields via the TiCl 4 promoted cyclization of acetals derived from phenethyl alcohols.