HPW-Catalyzed environmentally benign approach to imidazo[1,2-a]pyridines

• Luan A. Martinho and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2024, 20, 628–637, doi:10.3762/bjoc.20.55

• reproducible. Unsuccessful substrates for these reactions were also detected (Scheme 4). The use of 2-amino-3-hydroxypyridine provided a complex mixture of products (1H and 13C NMR analysis). When 6-amino-2-thiouracil was used, only the starting materials were recovered. Regarding the aldehyde component, the

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

• , most likely because of enhanced stacking of the bicyclic π-system [104][105]. However, beyond the original studies, 7-Cl-bT has not been further explored for either duplex or triplex stabilization. Similar to L, substitution of thymine with 2-thiouracil (s2U) or 5-halouracils (e.g., BrU, Figure 6

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

• Ksenia I. Kaskevich,
• Anastasia A. Babushkina,
• Vladislav V. Gurzhiy,
• Dmitrij M. Egorov,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2020, 16, 1947–1954, doi:10.3762/bjoc.16.161

• observed in the case of 6-trifluoromethyl-2-thiouracil that afforded 2- and 3-phosphonylated 5-oxothiazolopyrimidines in a 1:1 ratio. Keywords: chloroethynylphosphonate; heterocyclization; phosphonylated thiazolopyrimidines; phosphonylation; thiazolopyrimidine; 2-thiouracil; Introduction

• most accessible approach to the synthesis of 5H-thiazolo[3,2-a]pyrimidine-5(7)-ones is the reaction of 2-thiouracil derivatives with α-halo ketones and α-halo acids, involving successive alkylation and condensation steps (Scheme 3) [17][18][19][20][21]. A convenient one-step synthesis of

• between 2-thiouracil and propargyl bromide yielded 5H-thiazolo[3,2-a]pyrimidine-5-one (Scheme 5) [20][21][22][23][24]. Despite the wide variety of thiazolopyrimidines reported to date, phosphonylated analogues of compounds of this series are unknown. Of special interest is the design of molecules

Enzymatic synthesis and phosphorolysis of 4(2)-thioxo- and 6(5)-azapyrimidine nucleosides by E. coli nucleoside phosphorylases

• Vladimir A. Stepchenko,
• Anatoly I. Miroshnikov,
• Frank Seela and
• Igor A. Mikhailopulo

Beilstein J. Org. Chem. 2016, 12, 2588–2601, doi:10.3762/bjoc.12.254

• /10, 117997 GSP, Moscow B-437, Russia Laboratory of Bioorganic Chemistry and Chemical Biology, Center for Nanotechnology, Heisenbergstraße 11, D-48149 Münster, Germany 10.3762/bjoc.12.254 Abstract The trans-2-deoxyribosylation of 4-thiouracil (4SUra) and 2-thiouracil (2SUra), as well as 6-azauracil

• preparation of trans-N-deoxyribosylase from Lactobacillus helveticus NCIB 6557 [30] had been described [31]. As for an enzymatic synthesis of thioxopyrimidine nucleosides, Kalckar [32] as well as Friedkin and co-workers [33][34] disclosed the formation of 2-thiouracil riboside and 2'-deoxyriboside using 2

• -thiouracil and the corresponding α-D-pentofuranose-1-phosphates (dicyclohexylammonium salts) as substrates of horse liver thymidine phosphorylases (hlTP) (reviewed in [1]). Recently, Hatano et al. reported on the synthesis of 2-thiothymidine (2STd) and 1-(2-deoxy-β-D-ribofuranosyl)-2-thiouracil (2SUd) by the

Multicomponent reactions in nucleoside chemistry

• Mariola Koszytkowska-Stawińska and
• Włodzimierz Buchowicz

Beilstein J. Org. Chem. 2014, 10, 1706–1732, doi:10.3762/bjoc.10.179

• as Mannich bases) can serve as starting materials in the syntheses of a variety of compounds. The employment of a nucleoside as the hydrogen active component has been one of the most common variants of the Mannich reaction. Treatment of uracil (or 2-thiouracil) nucleosides 1 with aq formaldehyde and

• both electron-poor and electron-rich aldehydes. The four-component variant of the reaction employing 2-thiouracil led to compound 72 with a slightly lower yield than those obtained from pseudo-four component cascade leading to compounds 71. 5. The Biginelli reaction The Biginelli reaction (Scheme 26