136811-80-8Relevant articles and documents
Claisen Rearrangement of Prenyl Ethers of Isomeric Acetylnaphthols and Bisprenyl Ethers of 4,6- and 2,4-Diacetylresorcinols
Anjaneyulu, Ammanamanchi S. R.,Isaa, Balagopala M.
, p. 2089 - 2094 (2007/10/02)
Claisen rearrangements of the 3-methylbut-2-enyl(prenyl)ethers 3 and 9 of 2-acetyl-1-hydroxy- and 1-acetyl-2-hydroxynaphthalenes 1 and 2 and the bis(3-methylbut-2-enyl)ethers 12 and 18 of 2,4- and 4,6-diacetylresorcinols 11 and 17 have been studied under a variety of thermal and catalytic conditions. 2-Acetyl-4-(3-methylbut-2-enyl)naphthalene-1-ol 4 was the sole product on rearrangement of compound 3, in DMA or neat.Under catalytic conditions 3,4-dihydro-2,2-dimethyl-2H-naphthopyran 7 was obtained in poor yield.An isomeric pyran, 1,2-dihydro-3,3-dimethyl-3H-naphthopyran 10 (25-43percent) was obtained under both thermal and catalytic conditions from 9.The rearrangement of 12 under thermal conditions (DMA and neat) furnished 3-acetyl-2,4-dihydroxy-5-(3-methylbut-2-enyl)acetophenone 13 and 3,8-diisopropylbenzodifuran 14.Pd'' mediated rearrangement of 12 gave only the partially deprenylated ether, 3-acetyl-4-hydroxy-2-(3-methylbut-2-enyloxy)acetophenone 15 (29percent).While the isomeric ether 18 gave the monoprenyl ether, 5-acetyl-4-hydroxy-2-(3-methylbut-2-enyloxy)acetophenone 19 in quantitative yield (95percent).The rearrangment products were characterised and their formation rationalised in terms of allowed sigmatropic shifts( prenyl and H) followed by loss of prenyl or acetyl groups.The reactions of prenyl ethers are both comparable to those of the corresponding allyl ethers and consistent with the greater fixed double-bond character of the naphthalene system compared to that of benzene.Prenyl derivatives of benzene and naphthalene containing ortho - hydroxyacetophenone units were formed which have potential in synthesis.
