731-75-9

Upstream product

• 521097-44-9 3,4-dihydroalloxanthoxyletin 
• 29373-14-6 2,2-dimethylchromane-5,7-diol 
• 541-47-9 3-Methylbutenoic acid 
• 1191-16-8 3-methylbut-2-enyl acetate 
• 16348-68-8 5-methoxy-2,2-dimethyl-2,3-dihydro-pyrano[2,3-f]chromene-4,8-dione 
• 676529-26-3 toluene-4-sulfonic acid 5-hydroxy-2,2-dimethyl-4-oxo-chroman-7-yl ester 
• 54416-00-1 toluene-4-sulfonic acid 5-methoxy-2,2-dimethyl-chroman-7-yl ester 
• 50386-17-9 3,4-Dihydro-7-hydroxy-5-methoxy-2,2-dimethyl-2H-1-benzopyran 
• 883-09-0 5,7-dihydroxy-2,2-dimethylchroman-4-one 
• 108-73-6 3,5-dihydroxyphenol 
• 7661-00-9 5-methoxy-2,2-dimethyl-7-(toluene-4-sulfonyloxy)-chroman-4-one 
• 130364-30-6 7-hydroxy-5',5a'-dimethylpyrano[2',3'-f]-(2H)-chromen-2-one 
• 74-88-4 methyl iodide 

Relevant academic research and scientific papers

A catalyst-free one-pot construction of skeletons of 5-methoxyseselin and alloxanthoxyletin in water

In refluxing water and without an additional catalyst, electron-rich phenols could react with alkynoic acids or alkynoates to provide coumarin structures. The skeletons of two natural pyranocoumarins, 5-methoxyseselin and alloxanthoxyletin, could be constructed (total yield up to 76%) in an aqueous multicomponent reaction in which isoprenyl acetate, propiolic acid, and phloroglucinol were simply mixed and refluxed in water.

Natural and synthetic 2,2-dimethylpyranocoumarins with antibacterial activity

A new efficient synthetic approach to the natural coumarins 5-hydroxyseselin (5), 5-methoxyseselin (3), and (±) cis-grandmarin (9) is described as well as the synthesis of some new derivatives in the 5-methoxyseselin series (10-15). The natural coumarins 7-hydroxyalloxanthyletin (6), alloxanthoxyletin (8), and dipetalolactone (7) have also been obtained as secondary products. The type of fusion of the pyrano ring in all cases has been established by 2D NMR spectroscopy. The compounds have been studied for their in vitro antibacterial activity, which has been compared with that of some previously synthesized seselin derivatives. The most active compounds were 3, 7, 8, 11, and 14. Some structure-activity relationships are discussed.

Atom economy. Palladium-catalyzed formation of coumarins by addition of phenols and alkynoates via a net C-H insertion

A strategy to achieve ortho substitution of phenols initiated by an ortho-palladation to create coumarins was examined. Indeed, treatment of alkynoates with electron-rich phenols in the presence of a palladium catalyst and an acid does generate coumarins. The scope of the reaction with respect to the phenol and the alkynoates is defined. With unsymmetrical aromatic substrates, generally good regioselectivity that reflects the HOMO coefficients can be observed. In the course of these studies, numerous important naturally occurring coumarins have been synthesized, including fraxinol methyl ether, ayapin, herniarin, xanthoxyletin, and alloxanthoxyletin. The fact that a Pd(0) is the precatalyst rather than a Pd(+2) species and that an acid that reduces Pd(+2) salts, formic acid, functions better than other carboxylic acids raises doubts about the initial working hypothesis. A novel mechanism involving a palladium phenoxide formed from a hydridopalladium carboxylate and phenol is invoked to rationalize the results.

A CONVENIENT SYNTHESIS OF 2,2-DIMETHYLCHROMENES FROM 2,2-DIMETHYLCHROMANONES

2,2-Dimethylchromanones were very easily reduced to the corresponding alcohols by sodium borohydride-palladium chloride, and the alcohols were converted into the corresponding 2,2-dimethylchromenes by dehydration with potassium hydrogensulfate in high yields based on 2,2-dimethylchromanones