Naphthalene → Naphtho(2,1-b)furan

Participants

Reaction Steps

Alternatively, particularly for compounds of the formula II wherein R2 is a halogenoalkyl radical, 7-methoxy-1-tetralone (XVI) is acylated with an ester R2CO2Et to a β-diketone (XVII) which is reduced with sodium borohydride to the corresponding diol (XVIII). The diol is dehydrated with potassium hydrogen sulphate to the unsaturated alcohol (XIX) which is aromatised with 2,3-dichloro-5,6-dicyanobenzoquinone to the corresponding naphthalene derivative. Demethylation with boron tribromide to the naphthol (XX) followed by reaction with thioglycolic acid in the presence of base and thermal lactonisation gives the naphtho[2,1-b]furan derivative (XXI). The side chain hydroxy group is protected by reaction with tert-butyldimethylsilyl chloride to give a hydroxy-protected derivative which is alkylated to XXII with an iodoalkane, R4I, and the protecting silyl ether is removed with tetrabutylammonium fluoride to give the required compound of the formula II.

Provenance & Evidence