Approach to a New Dihydrofuran‐Fused Cyclic System by a Remarkable Switching of endo/exo Selectivity of a [4+2] Cyclo­addition Reaction

Abstract

An efficient synthesis of a new class of dihydrofuran‐fused tetracyclic compounds, possessing a 2‐oxa‐furano‐steroidal framework, has been achieved by successive electrocyclic reactions of benzocyclobutene derivatives. It has been revealed that the stereoselectivity of a key intramolecular [4+2] cycloaddition reaction can be controlled by installation of a bulky silyl substituent onto the furan ring resulting in the formation of the exo adducts, the opposite selectivity to that observed in our past related studies. Preliminary examinations of the bioactivities of the synthesized compounds have been performed and have revealed that they have potential as anti‐influenza agents. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Recent Advances in Benzocyclobutene Chemistry

“…Initial bioactive studies indicate that compounds 179 and 182 have potential as anti-influenza compounds (Scheme 31). [72] Suzuki et al have synthesized a tetracyclic lactone 191 containing β-phenylnaphthalene skeleton by utilizing BCB chemistry. Interestingly, β-phenylnaphthalene moiety was found in many natural products.…”

“…Initial bioactive studies indicate that compounds 179 and 182 have potential as anti‐influenza compounds (Scheme 31). [72] …”