Probable reaction cycle for formation of normal butyraldehyde from propylene (L = triphenylphosphine (TPP); A: product of reaction of ROPAC with carbon monoxide and TPP; B: addition product of A and propylene; C: alkyl complex resulting from rearrangement of B; D: acyl complex resulting from carbon monoxide insertion to C; E: dihydroacyl complex resulting from oxidative addition of hydrogen to D; F: product of elimination of butyraldehyde from E)