Hydroxyquinones Naphthoquinones

Diels-Alder reactions of 1235 synthesis of 1228, 1231, 1250, 1335 Quinone oxime tautomers 251, 252 Quinones—see also Aminoquinones, Anthraquinones, Arenolquinones, Benzoquinones, CaUxquinones, Hydroquinones, Hydroxyquinones, Naphthoquinones, Perylenequinones, Scabequinone reduction of 1108 Quinone units 1396... 

Rueping has further developed this theme by showing that diarylprolinol ether 55 efficiently catalyses the addition of hydroxyquinones to a variety of a,P-unsatu-rated aldehydes as a method for the preparation of both 1,4- and 1,2-naphthoquinones with remarkable levels of enantioselectivity [98],... 

Conjugate addition of acyl groups to naphthoquinones (3, 211).2 The acyl nickel carbonylate anion (1) undergoes conjugate addition to the ethylene ketal 2 to form a lithium adduct that can be trapped by allyl iodide to give 3 in 81% yield. This product can be converted in a few steps to the hydroxyquinone 4, a precursor of the naphthoquinone antibiotic deoxyfrenolicin (5). 

Ylides of hydroxyquinones 416 were synthesized by treatment of 2-hydroxy-1,4-benzoquinones 415 with an equimolar amount of (diacetoxyiodo)benzene (Scheme 2.121) [560]. The most important member of this class, 2-oxido-3-(phenyliodonio)-l,4-naphthoquinone (417), was prepared similarly by treatment of 2-hydroxy-1,4-naphthoquinone (lawsone) with an equimolar amount of (diacetoxyiodo)benzene [561]. 

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