Von Pechmann reaction

John EVO, Israelstam SS (1961) Use of cation exchange resins in organic reactions. I. The von Pechmann reaction. J Org Chem 26 240-242... 

The short and efficient stereospecific synthesis of the dimer-selective retinoid X receptor modulator was carried out in the laboratory of L.G. Hamann. The synthetic sequence began with the von Pechmann reaction between tetramethyltetrahydronaphthol and ethyl acetoacetate in 75% sulfuric acid solution. The desired coumarin was formed regioselectively and isolated in high yield. 

P-keto ester substituted coumarin von Pechmann reaction... 

Subhas Bose, D., Rudradas, A. P., Hari Babu, M. The indium(lll) chloride-catalyzed von Pechmann reaction a simple and effective procedure forthe synthesis of 4-substituted coumarins. Tetrahedron Lett. 2002, 43, 9195-9197. 

Barris, B. E., Israelstam, S. S. Use of small quantities of sulfuric acid and polyphosphoric acid in the von Pechmann reaction. J. S.African Chem. Inst. 1960, 13, 125-128. 

A later refinement and modification of this route was communicated139, wherein a new variation of the von Pechmann reaction was employed. The differentiated lactone (58) was converted to the acyl acetal (66) by a reduction (diisobutylaluminum... 

The final construction step utilized the modified von Pechmann conditions previously described (zinc carbonate/sodium bicarbonate) to fuse phenol (94) to the activated vinyl bromide (72), thereby affording aflatoxin Mj (13). The route discussed above also presents a formal total synthesis of aflatoxin M2 (14), since this is able to be prepared76 through the controlled catalytic hydrogenation of aflatoxin Mj (13). It should also be possible to apply this technology in a synthesis of aflatoxin GMt (15), by the use of a suitable substrate [possibly ( )] in the von Pechmann reaction with phenol (94). 

In the synthesis of coumarins by the von Pechmann reaction, a spiro-compound (251) was simultaneously formed from 4-chloro-2-methylphenol (and from 2,3,5-trimethylphenol). A possible mechanism for this reaction involves the formation of the lactone (252), which reacts with another molecule of the phenol. The condensation of the dicyano-ester (253) [obtained from malononitrile and ethyl cyanoacetate] with substituted o-hydroxybenzaldehydes yields substituted coumarinimines, e.g. (254).A series of 4,6,7-substituted coumarins have been prepared and assessed for their suitability in fluorescence labelling of polymers. Esters of the type PhCH CRCOaAr react with AICI3 to give coumarins, which are probably formed via dihydrocoumarins (255) by dearylation. ... 

Sanjay, K., Anil, S., Jagir, S. S. 2007. LiBr-mediated solvent free von Pechmann reaction Facile and efficient method for the synthesis of 2//-chromen-2-ones. ARKIVOC 2007(15) 18-23. 

Karimi B, Zareyee D. Design of a highly efficient and water-tolerant sulfonic add nanoreactor based on tunable ordered porous silica for the von Pechmann reaction. Oig Lett 2008 10 3989-92. 

Montazeri, N. Khaksar, S. Nazari, A. Alavi, S. S. Vahdat, S. M. Tajbakhsh, M. Pentafluorophenylammonium triflate (PFPAT) An efficient, metal-free and reusable catalyst for the von Pechmann reaction. /. Fluorine Chem. 2011, 132, 450-452. 

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