RESUMO
Synthesis of the A/D/E-ring core compounds of maoecrystal V was achieved. The key Diels-Alder reactions between tricyclic α-methylene lactones and Kitahara-Danishefsky dienes afforded the spirocyclic core compounds in a regioselective and stereoselective manner.
Assuntos
Lactonas , Estereoisomerismo , Lactonas/química , Lactonas/síntese química , Reação de Cicloadição , Técnicas de Química Sintética , Diterpenos/síntese química , Diterpenos/química , Compostos de Espiro/química , Compostos de Espiro/síntese química , Estrutura MolecularRESUMO
A two-pot synthetic method to construct the chiral syn-1,3-diol unit has been developed from three aldehydes and either Wittig or Horner-Wadsworth-Emmons reagents. In the first pot, chiral δ-hydroxy α,ß-unsaturated ketones are synthesized with excellent enantioselectivity by the organocatalyst-mediated asymmetric direct aldol reaction of two different aldehydes, followed by either Wittig or Horner-Wadsworth-Emmons reactions. In the second pot, domino acetalization with an aldehyde and subsequent oxy-Michael reaction proceeds in the presence of NaClO4 and a catalytic amount of Bi(OTf)3 (OTf=trifluoromethanesulfonate) to provide the chiral 1,3-syn-diol derivative with excellent diastereoselectivity. Diosponginâ C and yashabushidiolâ A have been synthesized efficiently by using the present method as a key step.