An asymmetric synthesis of the ABCD ring system of daphnilactone B is described. The synthesis features a tandem, double intramolecular, [4+2]/[3+2] cycloaddition of a highly functionalized, enantiomerically enriched nitroalkene to generate a pentacyclic nitroso acetal. The cycloaddition establishes six contiguous stereogenic centers including the critical CD ring junction that bears two quaternary stereogenic centers. Hydrogenolysis of the nitroso acetal followed by amide reduction and cyclization provided the AB rings. The methyl substituent on the A ring was installed in the correct configuration via hydrogenation of an exocyclic olefin in the final step.
An asymmetric synthesis of the ABCD ring system of n class="Chemical">daphnilactone B is described. The synthesis features a tandem, double intramolecular, [4+2]/[3+2] cycloaddition of a highly functionalized, enantiomerically enriched nitroalkene to generate a pentacyclic nitroso acetal. The cycloaddition establishes six contiguous stereogenic centers including the critical CD ring junction that bears two quaternary stereogenic centers. Hydrogenolysis of the nitroso acetal followed by amide reduction and cyclization provided the AB rings. The methyl substituent on the A ring was installed in the correct configuration via hydrogenation of an exocyclic olefin in the final step.
Authors: Scott E Schaus; Bridget D Brandes; Jay F Larrow; Makoto Tokunaga; Karl B Hansen; Alexandra E Gould; Michael E Furrow; Eric N Jacobsen Journal: J Am Chem Soc Date: 2002-02-20 Impact factor: 15.419
Authors: Vera Lúcia Patrocinio Pereira; André Luiz da Silva Moura; Daniel Pais Pires Vieira; Leandro Lara de Carvalho; Eliz Regina Bueno Torres; Jeronimo da Silva Costa Journal: Beilstein J Org Chem Date: 2013-04-30 Impact factor: 2.883