Siloxycyclopropane derivatives 3 with a suitable styrene side chain can effectively be ring opened to precursors 2 which undergo reductive ring closure with SmI2 to furnish benzannulated cyclooctanols 1 or lactones 7 derived thereof. Tricyclic lactone 7c can be further substituted by conversion into a bridgehead enolate and reactions with electrophiles.
作者:Hans-Ulrich Reißig、Faiz Ahmed Khan、Regina Czerwonka、Chimmanamada U. Dinesh、Aarif L. Shaikh、Reinhold Zimmer
DOI:10.1002/ejoc.200600360
日期:2006.10
A series of γ-oxo esters 27-34 was prepared from methyl 2-silyloxycyclopropanecarboxylates 1-9 as key building blocks in a flexible modular synthesis. Their samarium diiodide promoted cyclization to benzannulated cyclooctanol derivatives was systematically investigated. Samarium ketyl compounds derived from aldehydes 27 and 28 mainly provided tricyclic γ-lactones 38 and 39 as a result of a cis-selective