Natural product synthesis palladium-catalyzed allylation

C.i. Palladium-Catalyzed Allylation in the Synthesis of Five-Membered Ring Natural Product... 

Toyota, M., Hirota, M., Nishikawa, Y., Fukumoto, K., and Ihara, M. (1998) Palladium-catalyzed intramolecular allylic alkylation reaction in marine natural product synthesis enantioselective synthesis of (-l)-methyl pederate, a key intermediate in syntheses of mycalamides. J. Org. Chem., 63, 5895-5902. 

This methodology has been used to provide efficient protocols for the asymmetric allylic alkylation of p-keto esters, ketone enolates, barbituric acid derivatives, and nitroalkanes. Several natural products and analogs have been accessed using asymmetric desymmetrization of substrates with carbon nucleophiles. The palladium-catalyzed reaction of a dibenzoate with a sulfonylsuccinimide gave an advanced intermediate in the synthesis of L-showdomycin (eq 3). ... 

An intramolecular variation of the Heck reaction was used in the construction of the monoterpene alkaloid ( )-oxerime 395 [138]. Nucleophilic addition to 392 of an allyl anion equivalent produced 393, a precursor to an intramolecular Heck cyclization. Palladium-catalyzed ring closure afforded 394, an intermediate in the synthesis of the natural product 395. 

Much effort has been devoted to developing catalysts that control the enantioselectiv-ity of these substitution reactions, as well as the regioselectivity of reactions that proceed through unsymmetrical allylic intermediates. A majority of this effort has been spent on developing palladium complexes as catalysts. Increasingly, however, complexes of molybdenum, tungsten, ruthenium, rhodium, and iridium have been studied as catalysts for enantioselective and regioselective processes. In parallel with these studies of allylic substitution catalyzed by complexes of transition metals, studies on allylic substitution catalyzed by complexes of copper have been conducted. These reactions often occur to form products of Sj 2 substitution. As catalylic allylic substitution has been developed, this process has been applied in many different ways to the synthesis of natural products. ... 

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