56649-47-9Relevant articles and documents
A Continuous-Flow Method for the Desulfurization of Substituted Thioimidazoles Applied to the Synthesis of Etomidate Derivatives
Baumann, Marcus,Baxendale, Ian R.
, p. 6518 - 6524 (2017/12/02)
A simple yet robust flow set-up for the efficient desulfurization of a series of thioimidazoles is presented, which generates the corresponding imidazole derivatives in high yields. The strategic choice of peristaltic over piston pumps allowed reliable delivery of the heterogeneous stream of the thioimidazole substrate into a T-piece where it reacted with NaNO2 in the presence of acetic acid. This approach enabled the controlled and safe formation of the reactive nitrosonium species without uncontrolled exposure to hazardous nitrous oxide by-products as observed in related batch protocols. The value of the resulting imidazole products was further demonstrated by their conversion into various esters representing new derivatives of the known analgesic etomidate through an efficient one-pot Corey–Gilman–Ganem oxidation procedure.
Synthesis of fused imidazoles, pyrroles, and indoles with a defined stereocenter α to nitrogen utilizing mitsunobu alkylation followed by palladium-catalyzed cyclization
Laha, Joydev K.,Cuny, Gregory D.
experimental part, p. 8477 - 8482 (2011/12/04)
Nitrogen-containing fused heterocycles comprise many compounds that demonstrate interesting biological activities. A new synthetic approach involving Mitsunobu alkylation of imidazoles, pyrroles, and indoles followed by palladium-catalyzed cyclization has been developed providing access to fused heterocycles with a defined stereochemistry α to nitrogen. While ethyl imidazole or indole carboxylates are good substrates for Mitsunobu alkylation with optically pure secondary benzylic alcohols, the corresponding pyrroles are poor substrates presumably due to the increased pKa of the NH. The presence of a synthetically versatile trichloroacetyl functional group on the pyrroles significantly reduces the pKa and thereby facilitates Mitsunobu alkylation. Subsequent cyclization of the alkylated products mediated by palladium in the presence or absence of a ligand gave fused heterocycles in good to excellent yields.
Racemization of lower alkyl imidazole carboxylates
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, (2008/06/13)
Novel methods of preparing lower alkyl 1-(1-phenylethyl)-1H-imidazole-5-carboxylates in racemic as well as in optically pure isomeric form.
