A novel route to the diene 5, a known intermediate that
had been previously transformed into pinnaic acid (1) via
3,
5 would entail a cross metathesis reaction between 10 and
the dienoate 813 in the presence of Grubbs’ second generation
metathesis catalyst (7).14 Similarly, a cross metathesis
reaction between 10 and a dienoate such as 9, which bears
a leaving group R, would lead to 6, a possible intermediate
en route to halichlorine (2). The opportunity to extend the
scope of olefin cross metathesis15 rendered this general
approach to 1 and 2 particularly attractive. Olefin 10 would
in turn be prepared by a Curtius rearrangement of a
compound derived from 11, whose synthesis via an efficient
three-component reaction was reported by Heathcock.16
A novel route to the diene 5, a known intermediate thathad been previously transformed into pinnaic acid (1) via3,5 would entail a cross metathesis reaction between 10 andthe dienoate 813 in the presence of Grubbs’ second generationmetathesis catalyst (7).14 Similarly, a cross metathesisreaction between 10 and a dienoate such as 9, which bearsa leaving group R, would lead to 6, a possible intermediateen route to halichlorine (2). The opportunity to extend thescope of olefin cross metathesis15 rendered this generalapproach to 1 and 2 particularly attractive. Olefin 10 wouldin turn be prepared by a Curtius rearrangement of acompound derived from 11, whose synthesis via an efficientthree-component reaction was reported by Heathcock.16
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