An auto-tandem catalytic, branched-selective rearrangement of substituted N-alloc-N-allyl ynamides was developed. This reaction provides ready access to complex quaternary nitrile products with vinylogous stereocentres in excellent diastereoselectivity, including contiguous all-carbon quaternary centres. The stereochemical outcome is determined via a Pd(0) catalysed dipolar ketenimine aza-Claisen rearrangement and computational studies exemplify the key role ligand geometry plays.