Natural product synthesis aryl/vinyl halides

The Sonogashira coupling reaction of terminal alkynes with aryl or vinyl halides is a useful tool for carbon—carbon bond formation, and has found wide employment in areas such as natural product synthesis, the pharmaceutical industry, and material sciences. Novel recyclable Pd catalysts with fluorous ponytails in the ligand 2,2 -bipyridine were reported in a copper-free Pd-catalyzed Sonogashira reaction in a fluorous biphasic system (FBS) (Equation 4.19). The catalysts are only soluble in perfluorinated solvents at room temperature [41],... 

Mizoroki and Heck first reported their independent discoveries of palladium(0)-catalysed vinylations of aryl halides over 30 years ago [1], This transformation, now known as the Mizoroki-Heck reaction, can be broadly defined as the palladium(0)-mediated coupling of an aryl or vinyl halide (or triflate) with an alkene. The potential utility of this transformation in complex molecule synthesis was largely unappreciated for a number of years however, its application for the construction of complex organic molecules, including natural products, has flourished recently [2],... 

Now Pd-catalyzed carbonylation was used as one carbon elongation method and it has been used for the synthesis of biologically active substances and natural products. In this section, Pd-catalyzed carbonylation of aryl, vinyl, and benzyl halides and pseudo aryl or vinyl halides is described. 

Since the discovery of Pd-catalyzed carbonylation of aryl, vinyl, and benzyl halides by Heck in 1974, this reaction has been used for the synthesis of ester, amide, acid, and acid anhydride. We can nse enol triflate, aryl Iriflate, aniUne derivatives, and vinyl silane as the pseudo aryl or vinyl halide. This reaction has now been further extended for the synthesis of aldehyde and ketone by combination with transmetalation. These reactions have widely been used in organic syntheses, especially the syntheses of biologically active substances in the field of fine chemistry and the syntheses of natural products. 

Schemes 28.76 through 28.84 detail the cross-coupling between vinyl halides and aryl boron and their application in the synthesis of complex natural products.

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