Shvets O. 5-Methyl[1,2,4]triazolo[1,5-a]pyrimidines and related compounds: synthesis and functionalization

The study is devoted to the synthesis of low molecular weight 5 methyl[1,2,4]triazolo[1,5 a]pyrimidines and related compounds which are functionalized at position 6. 6 Functional derivatives of 7-methyl- and 7 unsubstituted 5 methyl[1,2,4]-triazolo[1,5 а]pyrimidines, their 4,7-dihydro- and tetrazole analogues – alcohols, acids, aldehydes were synthesized in this work for the firs time. Currently, they are characterized by the lowest molecular weight in their classes. The possibility of mutual transformation of 5-methyl-DTPM to 5-methyl-TPM and the backward synthesis of 5 methyl-DTPM from 5-methyl-TPM were shown. Two independent ways to the synthesis of 7 methyl- and 7 unsubstituted 5 methyl DTPM, which have no substituents by position 6, were developed. The first method is based on the deacylation of the corresponding 6 acetyl-5 methyl-DTPM. The second one is assumed the reduction of 6 unsubstituted 5 methyl-TPM with LiAlH4 in THF. The fact that starting 7 methyl- and 7 unsubstituted 5-methyl-TPM were reduced by LiAlH4 in THF only to 4,7 dihydroderivatives was explained by the formation of N(4) anion DTPM. These 7 methyl- and 7 unsubstituted 5 methyl-DTPM, which do not contain a substituent at position 6, are active C nucleophiles capable to the further functionalization. The efficient method towards the synthesis of N,N-dialkyl-β-ketosulfonamides via the Claisen condensation was proposed. In particular, N,N dimethyl β oxopropane-sulfonamide (which is the substance of the lowest molecular weight of its class) and N,N dialkyl(cinnamylmethyl)sulfonamides which in reactions with aminoazoles form 7 aryl-5 (sulfonamido)methyl-4,7-dihydroazolo[1,5 a]pyrimidines were successfully obtained.