No abstract

A new optically active diterpene lactone, sinulariolone [1], has been isolated as the major secondary metabolite in a Philippine collection of Sinularia flexihilis. The compound has a tricyclic structure and is more highly oxygenated than previously reported diterpenes from this species. The structure of 1 was elucidated by spectroscopy and its relative stereochemistry confirmed by single-crystal X-ray crystallography.

The mechanism of phosphine- and phosphite-induced migration of the imido group from sulfur to a Cp ring in a tosylimido-bridged cobaltadithiolene complex was investigated, and a probable intermediate was isolated and characterized. The presence of a large excess of PPh3 causes the formation of the imido- and phosphine-substituted Cp complex.

The reactions of a malonate (C(COOMe)2)-bridged complex with Lewis bases give novel sulfur ylide (M−S sulfur ylide) complex due to the cleavage of Co−C bond as determined by X-ray sturucture analysis. Acetate (CHCOOEt)- and methylene-bridged complexes, on the other hand, reacted with Lewis bases via an SN2 type reaction to give unstable M−S sulfur ylide complexes and stable six-membered-ring complexes.