Spirastrellolide B: Construction of the C(26)–C(40) Northern Hemisphere and a Related [5,5,7]-Bis-spiroketal Analogue
摘要:
Differential synthetic access to an advanced C26-C40 northern hemisphere fragment of splrastrellolide B and to a related [5,5,7]-bis-spiroketal analogue from a common intermediate has been achieved. Central to this venture is the regiocontrolled functionalization of a C(31-32) alkyne, exploiting different transition metal catalysts (cf. Pt-II and Au-I).
Total synthesis and determination of the absolute configuration of (+)-neoisoprelaurefucin
摘要:
The first total synthesis of the seven-membered ring ether marine natural product (+)-neoisoprelaurefucin (1) has been achieved employing a regioselective internal alkylation of amide 3, a novel sequence for removal of the triethylsilyl group from the resulting triethylsilyloxepene 2, and a bromoetherification of alcohol 16 as key steps. In addition, the absolute stereochemistry of the natural product was assigned. (C) 2003 Published by Elsevier Ltd.