An Approach to the Synthesis of 1-Propenylnaphthols and 3-Arylnaphtho[2,1-<i>b</i>]furans
摘要
A simple and efficient strategy for the synthesis of 1-propenylnaphthols from readily accessible 3-arylallylnaphthyl ethers has been developed. By using K 2 CO 3 as base and 2-methoxyethanol as solvent, direct access to a wide range of 1-propenylnaphthols can be achieved in generally good yield (up to 99%) with high stereoselectivity toward the Z isomer. The control experiments indicate that the reaction proceeds through a sequential Claisen rearrangement/isomerization process. Furthermore, starting from the same material, the highly valuable 3-arylnaphtho[2,1- b ]furans can be obtained in N, N -dimethylformamide and in the presence of Ag 2 O as the oxidant via a one-pot sequential Claisen rearrangement/isomerization/cyclization reaction. Mechanistic studies confirm that 1-propenylnaphthols are the key intermediates to form the 3-arylnaphtho[2,1- b ]furans. In addition, these two operationally simple and practical protocols could be scaled up to a gram level.