The first totalsynthesis of (±)-(Z)-9-(bromomethylene)-1,5,5-trimethylspiro[5.5]undeca-1,7-dien-3-one, a chamigrane sesquiterpene having a novel bromomethylene group is described.
Photoinduced zirconocene catalysis was utilized to achieve the reductivecoupling of ethers with remarkable activity and cross-selectivity. Mechanistic investigation revealed that photoexcitation of low-valent zirconocene facilitates the scission of benzylic C(sp3)−O bonds, resulting in benzylic radicals that recombine with Zr center. Subsequent carbomagnesiation generates benzylic Grignard reagents