18385-83-6

Upstream product

• 51765-10-7 2-[(Z)-3-hydroxy-1-propenyl]-4-methylphenol 
• 5651-90-1 1-methyl-4-(2-propynyloxy)benzene 
• 59036-42-9 4-methyl-1-(3-chloro-2-propenoxy)benzene 
• 108-24-7 acetic anhydride 
• 122323-28-8 3-Bromo-6-methyl-2H-chromene 
• 38445-23-7 6-methyl-chromen-4-one 
• 106-44-5 p-cresol 
• 53299-56-2 4-methyl-1-(2-chloro-2-propenoxy)benzene 
• 92-48-8 6-methylcoumarin 

Downstream Products

• 41786-37-2 2-(4-methoxyphenyl)-6-methyl-2H-chromene 

Relevant academic research and scientific papers

Synthesis of 2 h-chromenes via hydrazine-catalyzed ring-closing carbonyl-olefin metathesis

The catalytic ring-closing carbonyl-olefin metathesis (RCCOM) of O-Allyl salicylaldehydes to form 2H-chromenes is described. The method utilizes a [2.2.1]-bicyclic hydrazine catalyst and operates via a [3 + 2]/retro-[3 + 2] metathesis manifold. The nature of the allyl substitution pattern was found to be crucial, with sterically demanding groups such as adamantylidene or diethylidene offering optimal outcomes. A survey of substrate scope is shown along with a discussion of mechanism supported by DFT calculations. Steric pressure arising from syn-pentane minimization of the diethylidene moiety is proposed to facilitate cycloreversion.

Indium-catalyzed intramolecular hydroarylation of aryl propargyl ethers

Indium(iii) halides catalyze efficiently the intramolecular hydroarylation (IMHA) of aryl propargyl ethers. The reaction proceeds regioselectively with terminal and internal alkynes bearing electron-rich and electron-deficient substituents in the benzenes

Ph3PAuNTf2 as a superior catalyst for the selective synthesis of 2H-chromenes: Application to the concise synthesis of benzopyran natural products

Ph3PAuNTf2 (≈1 mol-%) catalyzes the selective cycloisomerization of substituted aryl propargyl ethers into 2H-chromenes in excellent yields. Benzofuran byproducts are formed only in the case of electron-deficient arenes, in up to 7% relative yield. The Ph 3PAuNTf2-catalyzed cyclization of aryl propargyl ethers was applied as a key step to the concise synthesis of the naturally occurring benzopyrans seselin, xanthyletin, precocenes I and II, 8-(3′,3′- dimethylallyl)wenteria chromene, and 2,2-dimethyl-8-prenylchromene-6-propenoic acid. Ph3PAuNTf2 is a general, highly efficient, and product-selective catalyst for the clean synthesis of 2H-chromenes from the cycloisomerization of aryl propargyl ethers.The Ph3PAuNTf 2-catalyzed cyclization was applied as a key step in the synthesis of several benzopyran-bearing naturally occurring substances. Copyright

Gold nanoparticles supported on TiO2 catalyse the cycloisomerisation/oxidative dimerisation of aryl propargyl ethers

Gold nanoparticles supported on TiO2 (～1%) catalyse in high yields the selective cycloisomerisation of aryl propargyl ethers into the corresponding 2H-chromenes, under heterogeneous conditions. 2H,2′H-3, 3′-Bichromenes resulting from a catalytic oxidative dimerization pathway are also formed as by-products. The Royal Society of Chemistry 2011.

The Au(I)-catalyzed intramolecular hydroarylation of terminal alkynes under mild conditions: Application to the synthesis of 2H-chromenes, coumarins, benzofurans, and dihydroquinolines

(Chemical Equation Presented) Operationally simple Au(I)-catalyzed intramolecular hydroarylation (IMHA) reactions of terminal alkynes that proceed in high yield and under very mild conditions are described. These processes involve low catalyst loadings, mild reaction temperatures, and short reaction times, require no cocatalysts or additives, and allow for the generation of a number of important heterocyclic motifs from readily accessible starting materials.

Synthesis of 2H-chromenes through the reduction of chromones with 9-BBN

Chromones were regioselectively reduced to 2H-1-benzopyrans through the 1,2-addition of 9-borabicyclo-[3.3.1]nonane. Although transition-metal complexes did not have a catalytic effect on the reaction, only by using palladium(II) chloride, could both 2H-1-benzopyran and dihydro-1-benzopyran be obtained to a similar extent. Also, the reduction of chromone using other organoboranes led not to 2H-1-benzopyran, but rather to chromanone through the reduction of only an olefin moiety.

Novel electrochemical route to 2-(α-alkoxyallyl)phenols - Cathodic eliminative ring opening reaction

Electrochemical reduction of 4-alkoxy-3-bromochromans in acetonitrile led to a facile ring cleavage reaction yielding (2(α-alkoxy- allyl)phenols which are not easily accessible.

A New Route to o-Allenylphenols

Cathodic reduction of 3-bromochromenes led to a ring-opening reaction yielding o-allenylphenyl acetates.

RADICAL CYCLISTION: SYNTHESIS OF 4H-FURO(3,2-c)-1-BENZOPYRANS

3,4-dihydro-3-bromo-4-(prop-2-ynyloxy)-2H-1-benzopyrans (3) undergo radical cyclisation when treated with nBu3SnH and AlBN to give good yield of 2,3,3a,9b,-tetrahydro-3-methylene-4H-furo(3,3-c)benzopyran (4).

THERMAL REARRANGEMENT OF CHLORINE-CONTAINING ALLYL ETHERS OF p-CRESOL. FORMATION OF 2H-CHROMENE

The thermal rearrangement of β- and γ-chloro- and β,γ-dichloroallyl ethers of p-cresol takes place by an intramolecular mechanism with inversion of the allyl unit of the initial ether.The final product from the rearrangement of γ-chlorine-containing ethers are 2H-chromenes, which are formed in parallel by two paths involving a -sigmatropic shift either with the formation of a classical Claisen phenol at the first stage or with the formation of propargyl ether (as a result of the elimination of HCl).In the presence of two chlorine atoms at the γ position the alkenyl aryl ethers do not change when heated under the adopted conditions.