✍ Scribed by Wolfgang Pfleiderer
No coin nor oath required. For personal study only.
A variety of pyrimidine precursors 12–25 were converted into a series of new 7‐hydroxylumazines (=7‐hydroxypteridine‐2,4(1__H__,3__H__)‐diones) 26–35 which functioned as starting materials for the transformation into the corresponding 7‐chlorolumazines 36–45. Subsequent reaction with hydrazine led to the 7‐hydrazinolumazines 46–55 which gave on nitrosation the 7‐azidolumazines 1 and 56–64. These compounds were subjected to short heating in xylene whereby 1 and 56–61 showed a new pteridine–purine interconversion in forming a new type of 1,3‐disubstituted or 3‐substituted xanthin‐8‐amine‐derived nitrilium ylides (2,3,6,7‐tetrahydro‐N‐methylidyne‐2,6‐dioxo‐1__H__‐purin‐8‐aminium ylides) 11 and 65–70. The presence of an additional 6‐alkyl substituent in the 7‐azidolumazines 63 and 64 or of an unsubstituted N(3) position in 62 caused further rearrangement to xanthine‐9‐carbonitriles 71–73. Prolonged heating of 7‐azido‐1,3‐dimethyllumazine (1) also afforded theophylline‐9‐carbonitrile (=1,2,3,6‐tetrahydro‐1,3‐dimethyl‐2,6‐dioxo‐9__H__‐purine‐9‐carbonitrile; 5). The nitrilium ylide function was established by NMR and UV spectra as well as by elemental analyses. Confirmation of the nitrilium ylide structures was suggested by the result of the heating of 1,3‐dimethyl‐N‐methylidynexanthin‐8‐aminium ylide 11 in EtOH or of 1 in pentan‐1‐ol leading to 8‐aminotheophylline (=8‐amino‐3,7‐dihydro‐1,3‐dimethyl‐1__H__‐purin‐2,6‐dione; 74).
📜 SIMILAR VOLUMES
## Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
## Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
## Abstract A new synthesis of pteridines possessing a (substituted) (__Z__)‐3‐hydroxyprop‐1‐enyl group at C(6) is based on the acylation of 4‐amino‐5‐nitrosopyrimidines with dienoic acid chlorides, followed by a high‐yielding intramolecular hetero‐__Diels–Alder__ cycloaddition and cleavage of the