106994-52-9Relevant academic research and scientific papers
Furan Derivatives. Part 8. On Substituent Effects in the Synthesis of 4,5-Dihydro-3H-naphthofurans
Horaguchi, Takaaki,Yagoh, Hiroaki,Tanemura, Kiyoshi,Suzuki, Tsuneo
, p. 657 - 663 (2007/10/02)
4,5-Dihydro-3H-naphthofurans 4 and 6 which have various substituents (R1 and R2) have been synthesized from 8-oxo-5,6,7,8-tetrahydro-1-naphthyloxyacetic acids 1 and 3 or their ethyl esters 2.The reaction of acids 1 and 3 with sodium acetate in acetic anhydride gave a mixture of furans 4 and 6 and lactones 5 and 7.The ratios of the products were varied according to the types of substituents (R1 and R2) in acids 1 and 3.As the substituent R1 (R2 = hydrogen) in acids 1 was changed from hydrogen to a methyl, ethyl or isopropyl group, production of furans 4 became more difficult.However, when a phenyl group was used as the substituent, furan 4 was obtained in good yield.Similarly, as the substituent R2 (R1 = hydrogen) in acids 1 was changed from hydrogen to a methyl, ethyl or isopropyl group, furan formation was more difficult.In contrast, acids 3 which had electron-withdrawing substituents such as chlorine, bromine or a nitro group at the 4-position afforded furans 6 in good yield. 4,5-Dihydro-3H-naphthofurans 4 and 4,5-dihydro-3H-naphtnofuran-2-carboxylic acids 8 were synthesized from the reaction of esters 2 and potassium hydroxide in dioxane.When the substituents R1 or R2 in esters 2 were varied from hydrogen to a methyl, ethyl or isopropyl group the total yields of furans 4 and furancarboxylic acids 8 were reduced.
