Assembly of the Bis(imidazolyl)propene Core of Nagelamides C and S by Double Grignard Reaction

Abstract

Keywords: Natural products / Alkaloids / Nitrogen heterocycles / NagelamidesAs characteristic structural elements of several of the nonmonomeric pyrrole-imidazole alkaloids, 1,1-bis(imidazolyl)-propenes were assembled in a facile manner by double Grignard reaction of metalated imidazoles with saturated esters, followed by dehydration. The presence of nitrile functions or acryl esters in the electrophile component leads to competing

Muscarine, imidaozle, oxazole and thiazole alkaloids

“…43 Various synthetic strategies have been developed during studies towards the total synthesis of alkaloids nagelamides C 40, S 41, and K 42. 44,45 The oroidin-derived alkaloids palau'amine 43, dibromophakellin 24, and dibromophakellstatin 26 were found to modulate the proteolytic activity of the human 20S proteasome, as well as the i20S immunoproteasome catalytic core. 46 In addition, palau'amine proved capable of preventing the proteolytic degradation of proteins, including the inhibitory-kB protein in cell culture.…”

C-N bond forming reactions in the synthesis of substituted 2-aminoimidazole derivatives

“…Thus, the imidazole ring could be lithiated at C-2, followed by reaction with azides and subsequent reduction to obtain 2-aminoimidazoles. [21][22][23][24][25][26] However, this procedure requires several steps, and has failed in the synthesis of some natural products, such as kealiiquinone. 27 To solve these problems, Lovely group has recently developed a convenient procedure for the direct conversion of imidazolium salts into 2-aminoimidazoles by using Nchloroamides at room temperature.…”

Synthesis of 2-Imidazolones and 2-Iminoimidazoles

“…8, 9 Whereas, the corresponding carbonyl moiety can be introduced by oxidation of the organometallic with a peroxide such as (TMSO) 2 10 or (PhCO 2 ) 2 . 11 This type of strategy has worked very well in a number of different settings both for us 12 and for other investigators, 13 including en route to modestly complex natural products.…”