129589-53-3Relevant academic research and scientific papers
Claisen rearrangement of allyl ethers of isomeric acetylnaphthols under catalytic conditions
Anjaneyulu, A S R,Isaa, B Meher
, p. 15 - 18 (2007/10/02)
Claisen rearrangement of the isomeric allyl ethers (1 and 6) of 2-acetyl-1-naphthol and 1-acetyl-2-naphthol has been studied using a Bronsted or protic acid (CF3COOH) and aprotic or Lewis acids as catalysts.The rearrangement of 1 in TFA gives 2-acetyl-1--naphthol (2), 1-acetoxy-2-allylnaphthalene (3) and 2-allyl-1-naphthol (4), but in BF3*OEt2 it resulted in only 4.However, Claisen rearrangement of 1 under Pd(II) mediation furnishes 2-acetyl-4-allyl-1-naphthol (5) and 4.The isomeric ether 6 rearranges in TFA to give 1-allyl-2-naphthol(7) and 2-acetoxy-1-allylnaphthalene (8) while resists rearrangement with BF3*OEt2.However, with Pd(II) it undergoes isomerisation of allyloxy double bond furnishing 1-acetyl-2-(cis-enyloxy)naphthalene (9).All the products have been characterised by their elemental analyses and spectral data (IR, UV, PMR, and mass) and their formation has been rationalised.
Thermal Claisen Rearrangement of Allyl Ethers of Isomeric Acetylnaphthols
Anjaneyulu, Ammanamanchi S. R.,Isaa, Balagopala M.
, p. 993 - 998 (2007/10/02)
Thermal Claisen rearrangement of the allyl ethers (3) and (12) of the isomeric 2-acetyl-1-hydroxy- and 1-acetyl-2-hydroxy-naphthalenes (1) and (2) has been studied by heating each in refluxing N,N-dimethylaniline (DMA) and neat at 185 deg C under N2 atmosphere. 2-Acetyl-4-allyl-1-hydroxynaphthalene (4), the sole product isolated from (3), was isolated in 56 and 88percent yield respectively under the two sets of conditions.The rearrangement of the allyl ether (12) gave 3-acetyl-1-allyl-2-hydroxynaphthalene (13) (18percent) and 2-acetoxy-1-allylnaphthalene (14) (23percent) in N,N-DMA while in the neat rearrangement it gave (14) as the major product (70percent) along with 1-allyl-2-hydroxynaphthalene (17) (20percent).The rearrangement of the allyl ether (7), obtained on further allylation of (4), furnished 2,4-diallyl-1-hydroxynaphthalene (8), (15percent) and (4) (15percent) in DMA while it gave 1-acetoxy-2,4-diallylnaphthalene (9) as the sole product (67percent) in the neat rearrangement.The rearrangement of the allyl ether (15), obtained by further allylation of (13), in DMA gave 3-acetyl-1,1-diallylnaphthalen-2(1H)-one (16) (20percent) along with (13) (6percent).The various rearrangement products have been characterised by their spectroscopic data (UV, IR, 1H NMR, and EI-MS) and the reactions rationalised by the allowed sigmatropic shifts such as > allyl, acetyl followed by loss of allyl or acetyl groups.The significant differences noticed in the reactions of the isomeric series of allyl ethers are consistent with the greater double-bond character of the naphthalene system compared to that of benzene as well as positional isomerism that exists in the allyl ethers.The above Claisen rearrangement studies result in the isolation of some interesting naphthylallyl derivatives with ortho-hydroxyacetophenone units which form useful synthetic intermediates for preparing several naphthyl-α- and γ-pyrone derivatives of pharmacological activity.
