Synthesis of 3(2)-phosphonylated thiazolo[3,2-a]oxopyrimidines

Autor: Ksenia I. Kaskevich, Anastasia A. Babushkina, Vladislav V. Gurzhiy, Dmitrij M. Egorov, Nataly I. Svintsitskaya, Albina V. Dogadina
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Beilstein Journal of Organic Chemistry, Vol 16, Iss 1, Pp 1947-1954 (2020)
Druh dokumentu: article
ISSN: 1860-5397
DOI: 10.3762/bjoc.16.161
Popis: A series of 3(2)-phosphonylated thiazolo[3,2-a]oxopyrimidines was synthesized for the first time by the reactions of chloroethynylphosphonates with unsubstituted and 5(6)-substituted 2-thiouracils. The reaction of chloroethynylphosphonates with 6-substituted 2-thiouracils bearing electron-donor groups (CH3, Ph) proceeded with high regioselectivity involving the cyclization through the N3-nitrogen atom to form new 3-phosphonylated thiazolo[3,2-a]-5-oxopyrimidines with good yield. In the case of unsubstituted and 5-methyl-2-thiouracils, cyclization occurred predominantly through the N1 atom and partially via the N3-nitrogen atom to form a mixture of the corresponding thiazolo[3,2-a]-7- and 5-oxopyrimidines. A dramatic change in the reaction regioselectivity was observed in the case of 6-trifluoromethyl-2-thiouracil that afforded 2- and 3-phosphonylated 5-oxothiazolopyrimidines in a 1:1 ratio.
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