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

• much greener as compared to methanol, it was chosen as the solvent to study the reaction scope. The use of water or solvent-free conditions resulted in much lower reaction yields (Table 1, entries 14–16). Next, the scope of the reaction was investigated with a range of 2-aminopyridines/2-aminothiazoles

• was applied to a broader range of aromatic/heteroaromatic or aliphatic aldehydes, 2-aminopyridines/2-aminothiazoles and isocyanides. Regarding some Green Chemistry metrics, our methodology proved superior at least considering E-factor and mass intensity. As can be seen in entry 6 of Table 2, our

A one-pot electrochemical synthesis of 2-aminothiazoles from active methylene ketones and thioureas mediated by NH₄I

• Shang-Feng Yang,
• Pei Li,
• Zi-Lin Fang,
• Sen Liang,
• Hong-Yu Tian,
• Bao-Guo Sun,
• Kun Xu and
• Cheng-Chu Zeng

Beilstein J. Org. Chem. 2022, 18, 1249–1255, doi:10.3762/bjoc.18.130

• and Life, Beijing University of Technology, Beijing 100124, China 10.3762/bjoc.18.130 Abstract The electrochemical preparation of 2-aminothiazoles has been achieved by the reaction of active methylene ketones with thioureas assisted by ᴅʟ-alanine using NH4I as a redox mediator. The electrochemical

• protocol proceeds in an undivided cell equipped with graphite plate electrodes under constant current conditions. Various active methylene ketones, including β-keto ester, β-keto amide, β-keto nitrile, β-keto sulfone and 1,3-diketones, can be converted to the corresponding 2-aminothiazoles. Mechanistically

• , the in situ generated α-iodoketone was proposed to be the key active species. Keywords: 2-aminothiazoles; electrosynthesis; indirect electrolysis; halide ion; Introduction Thiazoles are prevalent structural motifs in a wide range of natural products [1] and synthetic molecules possessing various

Visible-light-mediated copper photocatalysis for organic syntheses

• Yajing Zhang,
• Qian Wang,
• Zongsheng Yan,
• Donglai Ma and
• Yuguang Zheng

Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169

• thiocyanate to generate 4-alkyl/aryl-2-aminothiazoles. Mechanistic experiments demonstrated that the photocatalyst formed in situ from Cu(OAc)2 and ammonium thiocyanate promoted the intermolecular cyclization (Scheme 7). 3.2 Difunctionalization of alkenes The 1,2-difunctionalization of alkenes is a versatile

Access to highly substituted oxazoles by the reaction of α-azidochalcone with potassium thiocyanate

• Mysore Bhyrappa Harisha,
• Pandi Dhanalakshmi,
• Rajendran Suresh,
• Raju Ranjith Kumar and
• Shanmugam Muthusubramanian

Beilstein J. Org. Chem. 2020, 16, 2108–2118, doi:10.3762/bjoc.16.178

• azidochalcones, when treated with potassium thiocyanate in the presence of potassium persulfate, lead to 2,4,5-trisubstituted oxazoles in good yields. Incidentally, 2-aminothiazoles are the products when ferric nitrate is employed instead of persulfate in the above reaction. Keywords: aminothiazole; oxazole

• a report pertaining to this transformation with Fe(II) salts [73]. We further wanted to capitalize on this result and optimize the methodology to access a series of 2-aminothiazoles as the reported methods [74][75][76][77][78][79] to access 2,4,5-trisubstituted aminothiazoles, especially 4-aroyl-2

• the reaction mixture was heated for 6 h (Table 2, entry 7). Potassium ferricyanide has also been proved ineffective (Table 2, entry 10). Using the optimized experimental conditions, the Fe(III)-mediated formation of 4,5-disubstituted 2-aminothiazoles 4 was examined for the substrate scope (Scheme 8

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

• the formation of 5- and 7-oxothiazolopyrimidine-6-carbonitriles (Scheme 1) [12][13]. The synthesis of thiazolopyrimidines through the reaction of 2-aminothiazoles with 1,3-ketoesters in the presence of acids, bases or condensing agents (Scheme 2) has been studied fairly well [6][8][14][15][16]. The

• uracil ring, leading to the formation of 7-oxopyrimidines. Structure of ritanserin and setoperone drugs. One-pot synthesis of 5(7)-oxothiazolopyrimidine-6-carbonitriles. Synthesis of thiazolopyrimidine-5-ones through the reaction of 2-aminothiazoles with ethyl acetoacetate. Synthesis of 2-(benzo[d

N-Propargylamines: versatile building blocks in the construction of thiazole cores

• S. Arshadi,
• E. Vessally,
• L. Edjlali,
• R. Hosseinzadeh-Khanmiri and
• E. Ghorbani-Kalhor

Beilstein J. Org. Chem. 2017, 13, 625–638, doi:10.3762/bjoc.13.61

• to heterocyclic isothiocyanates and some reported examples are shown in Scheme 3b [85]. This strategy was elegantly used by Sasmal and co-workers in the preparation of 2-aminothiazoles 17 from ethyl 4-aminobut-2-ynoate salts 15 and isothiocyanates 16. Several bases and solvents were screened and the

• combination of Et3N and THF at room temperature was found to be superior. Under the optimized conditions, the reaction tolerates both aryl and alkyl isothiocyanates 16 and gave the corresponding 2-aminothiazoles 17 in good to high yields (Scheme 4a). The authors further expanded the scope of N-propargylamines

• to diethyl 3-aminoprop-1-ynylphosphonate salts 18 leading to 5-diethyl methylphosphonate-substituted 2-aminothiazoles 19 in good yields (Scheme 4b) [86]. An interesting approach towards the synthesis of 2-aminothiazole derivatives by treatment of N-propargylamines with isothiocyanates in the presence

Synthesis and enzymatic evaluation of 2- and 4-aminothiazole- based inhibitors of neuronal nitric oxide synthase

• Graham R. Lawton,
• Haitao Ji,
• Pavel Martásek,
• Linda J. Roman and
• Richard B. Silverman

Beilstein J. Org. Chem. 2009, 5, No. 28, doi:10.3762/bjoc.5.28

• products. A successful route to 2-aminothiazoles is outlined in Scheme 2. Epoxide 5 was opened with allylmagnesium bromide, and the resulting alcohol was protected as a TBS ether. The double bond was converted to an epoxide, which was then opened with bromide under acidic conditions [13]. A mixture of

• -methylpyridine. The methyl group at the 4-position of the pyridine ring contributes a significant amount to binding, resulting in a 4-fold increase in potency. There is no functionality in the 2-aminothiazoles to provide a similar hydrophobic interaction. If the 4-aminothiazoles had been stable, the alkyl group