Metal acyls are often generated by the reaction of low-valent metal centers with acyl chlorides.  Illustrative is the oxidative addition of acetyl chloride to Vaska's complex, converting square planar Ir(I) to octahedral Ir(III):
:IrCl(CO)(PPh) + CHCOCl → CHCOIrCl(CO)(PPh)
In rare cases, acyls can be produced from aldehydes by C-H oxidative addition. This reaction underpins hydroacylation.
In a related reaction, metal carbonyl anions are acylated by acyl chlorides:
:(CH)Fe(CO)Na + CHC(O)Cl → (CH)Fe(CO)COCH + NaCl
Another important route to metal acyls entails insertion of CO into a metal alkyl bond. In this pathway, the alkyl ligand migrates to an adjacent CO ligand. This reaction is a step in the hydroformylation process.
Coordinatively saturated metal carbonyls react with organolithium reagents to give acyls. This reaction proceeds by attack of the alkyl nucleophile on the electrophilic CO ligand.