SYNTHESES OF α- AND β-LAPACHONES AND THEIR HOMOLOGUES BY WAY OF PHOTOCHEMICAL SIDE CHAIN INTRODUCTION TO QUINONE

Abstract 1,4-Naphthoquinone photochemically reacted with 3-methyl-2-butenal to give 2-(3-methyl-2-butenoyl)-1, 4-naphthalenediol 3b, regiospecifically. The product 3b was successively treated with acid, with dichloroaluminum hydride, and finally with iron(III) chloride to derive in turn to cromanon 4b, dihydropyran 5b, and β-lapachone 6b. β-Lapachone was easily transformed to α-lapachone 7b by treating with acid. Likewise, from other α,β-unsaturated aliphatic aldehydes and 1,4-naphthoquinone α- and β-lapachone analogues were prepared.