ChemInform Abstract: A New Class of Fused Imidazoles by Intramolecular Nucleophilic ipso‐Substitution in 2‐Alkylsulfonylimidazoles: Synthesis of 2,3‐Dihydroimidazo[2,1‐b][1,3]oxazoles.

Abstract

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Five‐Membered Heterocycles with Four Heteroatoms: Tetrazoles

“…When a base like potassium t-butoxide is used to deprotonate the tetrazole, both N2 and N1 adducts 62 and 63, respectively, are obtained (Scheme 15.36) [60]. In contrast, when tetrazole is reacted directly, albeit on a strained epoxide, only N2 adduct 64 is obtained [61].…”

Synthesis of 2-Thio- and 2-Oxoimidazoles via Cascade Addition−Cycloisomerization Reactions of Propargylcyanamides

“…They have also been documented as key pharmacophores in agents for the treatment of thrombosis, inflammation, and asthma . The preparation of these heterocycles is usually accomplished by nucleophilic substitution of activated 2-sulfonyl-, 2-nitro-, or 2-haloimidazoles or by the alkylation of imidazolethiones . The substitution approach is often lengthy requiring multiple protecting group and oxidation manipulations, while alkylation is generally restricted to sp hybridized electrophiles and can give mixtures of S/O and N alkylated products.…”

Synthesis of 4,5-Substituted Imidazoles by a Fast Condensation of 1,2-Diketones and Urotropine in Heterogeneous Medium

“…1,6,11 The compounds are often synthesized in a solvent, and the presence of catalysts is frequently required. 2,[12][13][14][15][16][17] The significant amount of waste products, difficult accessibility of starting materials, and lower yields remain disadvantages of these methods. 1,2 Recently, a synthesis of 2,4,5-trisubstituted imidazoles in solvent medium with the aid of microwave irradiation was described.…”