Direct Access to 9/6-Fused Cycles via Sequential Hydride Shift Mediated Double C(sp3)-H Bond Functionalization

We have developed a sequential hydride shift process involving a [1,8]-hydride shift. When cinnamylidene malonates having a biphenyl core were treated with 30 mol% Yb(OTf)(3) and 10 mol% iPr(2)NEt, the desired sequential [1,8]-[1,5]-hydride shift process proceeded smoothly to afford synthetically challenging nine-membered carbocycle-fused piperidine derivatives in good chemical yields (up to 77%). Notably, the desired nine-membered carbocycles could not be obtained by a single [1,8]-hydride shift/cyclization process, suggesting that the employment of the sequential system is crucial to achieving the reaction.