Have a good SIP: P‐stereogenic secondaryiminophosphorane (SIP) ligands with a sulfonyl group attached to nitrogen have been prepared. In the presence of rhodium, the tautomeric equilibrium is shifted from the favored PHtautomer towards the PIII tautomer, thereby allowing coordination of the SIP ligand through the P and O atoms. The resulting Rh complexes are effective in the [2+2+2] cycloaddition