Studien auf dem Gebiet der Naturstoffchemie, 80. Cyclisierungen und Claisen‐Umlagerungen 3‐O‐substituierter 1,3‐Dihydroxy‐10‐methyl‐9(10H)‐acridinone — Synthese des Furacridons

Abstract

Selective etherification of the 3-hydroxy group of 1,3-dihydroxy-l0-methyl-9(10H)-acridinone (la) gave the ethers l c -e. Cyclodehydration of l c yielded a mixture of furacridone (2) and 3a in a ratio of about 6: 1. Claisen rearrangement or cyclization of Id and l e in N,N-diethylaniline led to the isomeric mixtures l i and l h as well as 4 and 5 in ratios of 5 : 1 and 6: 1 , respectively, in favour of the C-6substitution. By rearrangement of l e in HMPT the linear 3b has been obtained. Ein allgemeiner Syntheseweg zu Furo-(bzw . Pyrano-)acridonen fuhrt iiber zur Cyclisation befahigte C-3-Ether von l a , wobei die neue C,C-Verknupfung am c-4 oder c-2 Aus Wurzelrinde von

Chemistry of Acronycine VI. Proton NMR Spectral Assignments of Acronycine and Derivatives and the Formation of Isonoracronycine

“…Consequently, we were interested in the comparison between the two nuclei and also in simple methods to distinguish the two skeleta since this had been such a problem in the past. Some assignments of the 1H-NMR spectra of acronycine (5,21), noracronycine (6,10,22), des-N-methylacronycine (17), isonoracronycine (21) and several other simple acronycine derivatives (14,21,(23)(24)(25)(26) have been reported previously. However, this report constitutes the first complete set of assignments for any unsubstituted acronycine derivatives.…”

“…This transient nOe technique therefore permits a facile distinction between the isoacronycine series and acronycine series since in the former instance irradiation of the singlet aromatic proton (H-12) of isonoracronycine (3) caused a 5.4% enhancement in the N-methyl resonance. Such nOe techniques have been used previously in this series of compounds (15,24), but with the improved software and instrument sensitivity now available, which permit smaller nOe effects to be observed, this is now an even more attractive technique.…”

Chemistry of Acronycine I. Carbon- 13 NMR Studies of Acronycine and Related Compounds

“…It is well established (30) that in N-methyl acridone (10) the methyl group is in the plane of the nucleus, whereas in 5-bromodihydroacronycine (11) (8), and in an acronycine dimer (31), the methyl group is 18°out of the plane. This effect is clearly related to the presence of a substituent at C-4, as the recent work on the pyrano-acridones 12 and 13, which display N-CH3 resonances at 43.07 and 33.88 ppm, respectively (16), shows. A somewhat smaller effect (-3.5 ppm) is observed in the rutacridone series (15).…”

Chemistry of Acronycine, XI. Rearrangement of Dihydronoracronycine to Dihydroisonoracronycine-Mechanistic Studies

“…To establish the need for the geminal methyl signals in the rearrangement, the chemistry of the corresponding bis-nor derivative was studied. When a 1:6 mixture of 13 and 14 (17) was catalytically hydrogenated, two dihydro derivatives, 15 and 16, were isolated. The skeletons of these compounds were confirmed by nOe experiments.…”