Synthesis And Modification Of(4R,S)- 4,8-Dihydroxy-1-tetralone

4,8-dihydroxy-l-tetralone was a natural product with significant biological activities, which was first isolated from a Scytalidium species. Two absolute configurations, Regiolone and Isosclerone, which both exhibited strong apoptotic activities on human cancer cells and phytotoxicity, were reported isolated from plants and fungi. As a phytotoxin,4,8-dihydroxy-l-tetralone significantly inhibited seed germination and seedling growth, and this may lead to its use as a natural occurring herbicide in controlling weed growth in sustainable agriculture. To further investigation, an effect way of synthesis of 4,8-dihydroxy-l-tetralone was necessary. However, relatively little work has been reported on synthesis of 4,8-di-hydroxy-1-tetralone, and the known method was limited by raw materials and yield.In this paper, the five-step synthesis was first reported, with simple and easily available 1,5-dihydroxynaphthalene as the raw materials.5-hydroxy-3,4-dihydro-naphthalen-1(2H)-one was prepared from 1,5-dihydroxynaphthalene through catalytic reduction. Treatment of 5-hydroxy-3,4-dihydro-naphthalen-1(2H)-one with sodium borohydride afforded 1,2,3,4-tetrahydronaphthalene-1,5-diol. Oxidation of 1,2,3,4-tetrahydronaphthalene-1,5-diol using excess pyridinium dichromate gave 4,8-di-hydroxy-l-tetralone in good yield. Single factor experiments were taken to optimize reaction solvent, reaction time, reaction temperature and material ratio, and with the orthogonal design study on factors affecting the reaction, an ideal process route was achieved.In order to get more active compounds and provide more potential matter for herbicide, modification of 4,8-dihydroxy-l-tetralone by bimolecular nucleophilic substitution reaction using brominating reagent was investigated. After the selective protection of phenolic hydroxyl group and an alcoholic hydroxyl group, some groups with different hydrophilicity were respectively introduced into the molecule. This afforded six new compounds:5-hydroxy-4-oxo-1,2,3,4-tetrahydronaphthalen-1-yl benzoate,8-hydroxy-4-(3-hydroxypropoxy)-3,4-dihydronaphthalen-1(2H)-one,4-(2,3-dihydroxypropoxy)-8-hydroxy-3,4-dihydronaphthalen-1 (2H)-one,5-hydroxy-8-oxo-5,6,7,8-tetrahydronaphthalen-1-yl benzoate,4-hydroxy-8-(3-hydroxypropoxy)-3,4-dihydronaphthalen-1(2H)-one,8-(2,3-dihydroxypropoxy)-4-hydroxy-3,4-dihydro-naphthalen-1 (2H)-one.