The study on the key steps of carbonylations and double carbonylations results in finding five synthetically important catalytic reactions. i) Palladium catalyzed carbonylation of allyl phosphates, ii) palladium catalyzed carbonylation of allyl acetates, iii) rhodium catalyzed azacarbonylation of allyl phosphates, iv) palladium catalyzed carbonylation of allylamines, v) palladium catalyzed cross double carbonylation of amines and alcohols. Carbonylated products such as β, γ-unsaturated carboxylic acids, their esters and amides, and oxamates are versatile synthetic intermediates for organic synthesis. The mechanistic aspects of these reactions and synthetic applications are described.