RESUMEN
Various aryl Fischer carbenes reacted with alkynes having adjacent acyloxy or carbonate groups to regioselectively deliver 3-substituted 1-indanones. The acyloxy or carbonate group probably coordinates with the Cr metal to give a tetra-coordinated chromium complex forming a six-membered ring that retards CO insertion for ketene formation, which is required for benzannulation. Alternatively, the ortho position aryl ring attack results in pentannulation, providing regioselectively 3-substituted 1-indanones. The method is extended to the synthesis of the core structure of 3-epi-mutisianthol.
RESUMEN
The first stereoselective total synthesis of (-)-asteriscunolide C has been accomplished in 12 steps in a 16% overall yield. The key step is the conversion of a 12-membered to a strained 11-membered ring with one Z- and two E-double bonds employing a late stage ring-closing metathesis.
Asunto(s)
Antineoplásicos/química , Lactonas/química , Sesquiterpenos/química , EstereoisomerismoRESUMEN
A general, efficient, and common strategy for the synthesis of (-)-juglomycin A, (+)-kalafungin, (+)-frenolicin B, and (+)-deoxyfrenolicin is reported here. The strategy involves the synthesis of a key building block alkyne from a cheap chiral pool material, D-glucono-δ-lactone, Dötz benzannulation, oxa-Pictet-Spengler reaction, and H(2)SO(4)-mediated epimerization.
Asunto(s)
Alquinos/química , Estructura Molecular , Naftoquinonas/síntesis química , Naftoquinonas/química , EstereoisomerismoRESUMEN
A stereoselective synthesis of (-)-1-epi-ventiloquinone L and (+)-ventiloquinone L, the monomeric unit of cardinalin 3 has been described. The synthesis is completed in 7 steps with 10.5% and 13% overall yields for (-)-1-epi-ventiloquinone L and (+)-ventiloquinone L respectively. The key steps involve Dötz benzannulation of carbene 5 with alkyne 6 to give a substituted naphthalene moiety and oxa-Pictet-Spengler reaction to install the 1,3-dimethylpyran moiety.