External reagents Michael additions

Greaney and coworkers have introduced the conjugate addition of thiols to Michael acceptors as an effective adaptive DCL strategy [46,47]. The reaction is well suited for biological DCL synthesis, taking place in water with no requirement for external reagents. As with disulfide bond formation, the reaction is subject to simple and effective pH control. Under mildly basic conditions, the thiolate anion adds rapidly to Michael acceptors under equilibrium conditions. Acidification effectively switches the reaction... [Pg.73]

The Michael-type addition reaction of a carbonucleophile with an activated olefin constitutes one of the most versatile methodologies for carbon-carbon bond formation [1]. Because of the usefulness of the reaction as well as the product, many approaches to the asymmetric Michael-type addition reactions have been reported, especially using chirally modified olefins [2-8]. However, the approach directed towards the enantioselective Michael-type addition reaction is a developing area. In this Chapter, the recent progress of the enantioselective Michael-type addition reaction of active methylene compounds and also organometallic reagents with achiral activated olefins under the control of an external chiral ligand or chiral catalysts will be summarized [9]. [Pg.491]