Summary: Pyrroloimidazoles have been synthesized by diastereoselective of 1,3-dipolar cycloaddition by using 4, 5-dihydroimidazolium ylides with an alkylating agent and base.
Pyrrolo-[1, 2-a] imidazoles have been synthesized by diastereoselective of 1,3dipolar cycloaddition by using 4, 5-dihydroimidazolium ylides with an alkylating agent and base or more recently carbenoid insertion to dihydroimidazoles.
Pecharsky points out another intriguing difference between conventional solvent-based ylide generation and ball-milling: the bases required for each process.
In one experiment, described in volume 124, issue 22 (2002) of the Journal of the American Chemical Society, he and his colleagues generated compounds known as phosphorus ylides (or phosphoranes) without solvents, the first time such a feat had been reported.
In this work, they present 13 review articles describing various aspects of this emerging field, including asymmetric synthesis of chiral sulfoxides, asymmetric synthesis of optically active sulfinic acid esters, asymmetric transformations mediated by sulfinyl groups, synthesis and applications of chiral dithiocetal derivatives, synthesis and use of chiral sulfur ylides
, synthesis and use of chiral sulfoximines, synthesis and use of chiral sulfinamides, asymmetric catalysis using sulfoxides as ligands, sulfones in asymmetric catalysis, and computational studies on asymmetric reactions with sulfur reagents.
Our preliminary studies aim to investigate electrocylizations using stabilized azomethine ylides
in order to develop optimum reaction conditions.
Several new and very promising families of strong neutral bases--"proton sponges" [31-33], guanidines , amidines, phosphazenes [28-30, 35, 36], phosphorus ylides [37, 38]--have emerged.
Free and supported phosphorus ylides as strong neutral Bronsted bases.