Although rare , there are examples where antarafacial shifts are favored : In contrast to hydrogen [ 1,5 ] shifts , there have never been any observed [ 1,5 ] alkyl shifts in an open-chain system .
Although such reactions are rare , there are examples where antarafacial shifts are favored : In contrast to hydrogen [ 1,5 ] shifts , there have never been any observed [ 1,5 ] alky shifts in an open-chain system .