Transmissive Olefination Route to Putative “Morinol I” Lignans
2012-04-06T00:00:00Z (GMT) by
A series of morinol-type lignans were rapidly assembled using a Grignard-based transmissive olefination. In combination with palladium-catalyzed arylations, the strategy provides stereoselective access to (7<i>Z</i>,7′<i>E</i>), (7<i>E</i>,7′<i>E</i>), and (7<i>E</i>,7′<i>Z</i>) morinol diastereomers and the (7<i>Z</i>,8′<i>E</i>) and (7<i>E</i>,8′<i>E</i>) conjugated analogues. Critical for the <i>E/Z</i> stereoselectivity is a new, general method for converting alkenenitriles to alkenemethanols that circumvents the enal <i>E/Z</i> isomerization commonly encountered during conventional <i>i</i>-Bu<sub>2</sub>AlH reduction.