108298-70-0Relevant articles and documents
Syntheses of Highly Substituted Benzenes via Diels-Alder Reactions with 2H-Pyran-2-ones
Ziegler, Thomas,Layh, Marcus,Effenberger, Franz
, p. 1347 - 1356 (2007/10/02)
The 2H-pyran-2-ones (α-pyrones) 1 react as dienes in Diels-Alder reactions with acetylene derivatives.The primarely formed cycloadducts immediately aromatize to benzenes by CO2 elimination.Thus, methyl acetylenedicarboxylate (2a) gives dimethyl phthalates 3, and methyl acetylenediphosphonate (2b) gives dimethyl 1,2-phenylenediphosphonates 8.The reactions of 1-(dimethylamino)-1-methoxyethene (9) with 1 regioselectively produce N,N-dimethylanilines 10 and isomeric homophthalate derivatives 12.Naphthoquinones 14 could be generated from 1,4-benzoquinone (13) and 1 in the presence of acetic anhydride and Pd/C.Hydroxy-2H-pyran-2-ones 4 react via their trimethylsilyl ether 6 analogously with 2a to give dimethyl (trimethylsiloxy)phthalates 7 which are easily converted to phenols 5 by acid-catalyzed hydrolysis.