Naphthalenic and Polycyclic Systems with Two Hydroxyl Groups

Naphthalenic and Polycyclic Systems with Two Hydroxyl Groups 

Naphthalenic diols may conveniently be classed as dihydric phenols and as such they have been used both synthetically, the synthesis of morphine by M. Gates in 1954 being an example of one application of 2,6-dihydroxynaphthalene. The reaction chemistry of 1,3- and 1,5-isomers has been studied more recently. Naphthalene-1,3-diol in pyridine added to a toluene suspension of solid potassium superoxide under argon foiiowed after 5 mins, by quenching with water gave 2-hydroxy-1,4-naphthaquinone in 60% yield (ref. 193). 

Naphthalene-1,5-diol and 4-dimethylaminoaniline in ethanol/water (1 1) stirred for 1 hour with 4 moles of potassium ferricyanide at ambient temperature and then diluted with water gave the quinoneimine shown in 85% yield (ref.194). The compound can be hydrolysed to juglone, 5-hydroxy-1,4-naphthoquinone. 

1-Hydroxy-5-methoxynaphthalene underwent a Mannich reaction with cyclohexyl amine and 2 moles of 35% formalin in methanol until reaction was complete leading to an 80% yield of 3-cyclohexyl-2,4-dihydro-7-methoxy-2H-naphth[2,1 -e][1,3]oxazine although secondary amines afforded normal 2-dialkylamino methylation (ref.195). This reaction has been referred to in an earlier Chapter. 

7-Dihydroxynaphthalene with 4-phenyl-2,4-dioxobutanoic acid upon addition to phosphorus oxychloride gave after reaction during 20 hours at ambient temperature, 

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