Af unctionalized bicyclic lactam that was used as ak ey intermediate in an efficient synthesis of the pharmacophore of potent marine toxin spirolide Cw as synthesized by using ah ighly selective Diels-Alder reaction. To improve the reactivity of this transformation without loss of selectivity, substrates that contained as ilyl ether or silatrane moiety were elaborately designed and converted into the spirobicyclic core structure with stereochemical control over the two asymmetricc enters at the C7 and C29 positions. Moreover, af urther CÀCb ond formation by using aH iyama cross-coupling reaction of the vinyl silatraned erivativef acilitated versatile modification at the C5 position with an aryl or alkenyl substituent.

Efficient synthesis of the partial structure of marine toxin 13-desMe spirolide C was achieved via the selective Diels–Alder reaction and C–C bond formation with the use of a silatrane substituent and the subsequent facile formation of a γ-butenolide ring. The comparison of NMR data between the synthesized diastereomers and the natural product strongly suggested that the relative configuration at the C4 position was S configuration with respect to the 7,6-spirocycle.