Quinone-imides

Scheme II (Quinone Imide and Quinone Methine Imide Products)...

Corey s retrosynthetic concept (Scheme 9) is based on two key transformations a cationic cyclization and an intramolecular Diels-Alder (IMDA) reaction. Thus, cationic cychzation of diene 50 would give a precursor 49 for epf-pseudo-pteroxazole (48), which could be converted into 49 via nitration and oxazole formation. Compound 50 would be obtained by deamination of compound 51 and subsequent Wittig chain elongation. A stereocontroUed IMDA reaction of quinone imide 52 would dehver the decaline core of 51. IMDA precursor 52 should be accessible by amide couphng of diene acid 54 and aminophenol 53 followed by oxidative generation of the quinone imide 52 [28]. 

IOB in methanol was the best reagent for the conversion of sulphonamides into quinone-imide monoketals, e.g [47] ... 

The indamines are derivatives of quinone-imide, and accordingly a change from a tertiary to a secondary carbon atom must be accepted in the constitutional formulae of these bodies. 

These bodies certain of which have been used as dyestuffs, are derived from the simple ketones in the same manner as the quinone-imides and quinone-hydrazides from the diketones (quinones). Here, however, the chromophor occurs in an open carbon chain, and as it is only of a weak character, requires a salt-forming group to develop the properties of a dyestuff. The colour produced is always yellow. 

The behaviour of certain tertiary indamines shows that their production is attended by an intermediate formation of a quinone-imide. If, on the one hand, paraphenylenediamine is oxidised with dimethylaniline, and, on the other, unsymmetrical dimethyl-paraphenylenediamine [(CH3)2NC6H4NH2] with aniline, indamines are formed in both cases, but are not identical with each other, but isomerie, as by further action of aniline they yield two different dimethylsaffranines. 

Adams, R., Werbel, L. M., Nair, M. D. Quinone imides. XLVI. The addition of heterocyclic active methylene compounds to p-benzoquinone diimides. J. Am. Chem. Soc. 1958, 80, 3291-3293. 

The final B ring formation by intramolecular N-alkylation requires a C2 side chain attached to the A ring of the C5-spiroisoquinoIine educt, e.g. 133. This has been similarly obtained as the related educt 119 (Scheme 16) by reaction of the lithiated phenethyl derivative 131 with the N-protected quinone imide ketal 132. After deprotection the crude amine undergoes cyclization to form the 15-0-methylerysodienone (134) in 80% yield (77) (Scheme 18). 

Scheme 16 Photochemical Synthesis of Indoles from Quinones and Quinone Imides...

Red and blue salts discovered by C. Wurster as intermediates in the oxidation of paradiamines, were formulated as CgHuNaBr and CioHisNgBr, respectively. Bernthsen found that the red salt had quinonoid properties and formulated it as a quinone imide. Willstatter and J. Piccard regarded it as a meriquinonoid compound analogous to quinhydrone, but later work by L. Michaelis points to its being an odd molecule with a deficiency of one electron on one nitrogen atom. 

The derivatives of ortAo-aminophenethylamine were converted to indoline 1,4-quinone imides (eq 9). No oxidation at the 3-position or 4-position was observed if the a-position was occupied by two alkyl groups. 

Adams R, Winnick CN (1951) Quinone imides. VIII. Synthesis and reactions of o-quinone diimides. J Am Chem Soc 73(12) 5687-5691. doi 10.1021/ja01156a058... 

Scheme 17.16) [56]. It was proposed that the observed preference for the major product 86 arose from the energetically favored cnclo transition structure of quinone imide 89. It was suggested that the alternative endo transition structure 90, leading to minor diastereomer 87, was disfavored because of an unfavorable A interaction. Cycloadduct 86 was subsequently elaborated into the proposed structure 88 of the antitubercular diterpene pseudop-teroxazole. Corey s elegant total synthesis firmly established that the reported structure of the natural product had been misassigned.

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