Gold-catalyzed oxycyclization of allenic carbamates: expeditious synthesis of 1,3-oxazin-2-ones

• Benito Alcaide,
• Pedro Almendros,
• M. Teresa Quirós and
• Israel Fernández

Beilstein J. Org. Chem. 2013, 9, 818–826, doi:10.3762/bjoc.9.93

• be concluded that the observed divergent cyclization finds its origin in the initial 6-endo versus 6-exo oxyauration reaction steps, with the former being kinetically favored whereas the latter is thermodynamically favored. At this point, it cannot be safely discarded that the formation of the

Parallel and four-step synthesis of natural-product-inspired scaffolds through modular assembly and divergent cyclization

• Hiroki Oguri,
• Haruki Mizoguchi,
• Hideaki Oikawa,
• Aki Ishiyama,
• Masato Iwatsuki,
• Kazuhiko Otoguro and
• Satoshi Ōmura

Beilstein J. Org. Chem. 2012, 8, 930–940, doi:10.3762/bjoc.8.105

• undertaken. Keywords: chemical diversity; divergent cyclization; indole alkaloids; modular assembly; rhodium-catalyzed cyclization–cycloaddition; skeletal and stereochemical diversity; Introduction Biologically intriguing natural products often possess cyclic scaffolds bearing dense arrays of functional

• collections of the elaborated cyclic scaffolds, nature has evolved biosynthetic machinery and often employs (1) modular assembly and (2) divergent cyclization [4]. As the simplest example of this structural diversification, the biosynthesis of aromatic polyketides is outlined in Figure 1a. Employing acetyl

• connection of simple building blocks, as well as divergent cyclization of a common precursor leading to distinct skeletons with complex molecular architectures. Since the naturally occurring indole alkaloids share indole and piperidine as common substructures (Figure 1b) [6], we conceived the assembly of the