The difunctionalization of unsaturated hydrocarbons, the incorporation of two functional groups onto an unsaturated carbon-carbon bonds, is one of the most active and popular topics in modern organic chemistry due to its significance in the rapid and highly atom economical synthesis of complex molecules from simple starting materials within a single click. Among various difunctionalization reactions, difunctionalizing carboxylations utilizing CO₂ as a renewable and environmental friendly C1 feedstock has attracted more and more attention in recent years. In this regard, several interesting strategies have been developed in the last two decades for the preparation of branched carboxylic acids and their derivatives through the alkylative/arylative carboxylation of the corresponding unsaturated hydrocarbons using CO₂ as a carboxyl source. Thus, it is an appropriate time to summarize those advances. The purpose of this Mini-Review is to focus on the most important advances and developments on the attractive research field with particular emphasis on the mechanistic features of the reaction pathways. Notably, we have organized this review based on the type of bond where the CO₂ insertion occurs.

不饱和烃的双官能化，将两个官能团并入一个不饱和碳-碳键上，是现代有机化学中最活跃和最受欢迎的话题之一，因为它在从简单的复杂分子快速和高度原子经济的合成中具有重要意义。单击即可开始材料。在各种双官能化反应中，利用 CO _{2 的}双官能化羧化反应C1作为一种可再生、环保的原料，近年来受到越来越多的关注。在这方面，在过去的二十年中，已经开发了几种有趣的策略，用于通过使用 CO ₂作为羧基源的相应不饱和烃的烷基化/芳基化羧化来制备支链羧酸及其衍生物。因此，现在是总结这些进展的适当时机。本小型综述的目的是关注有吸引力的研究领域中最重要的进展和发展，特别强调反应途径的机械特征。值得注意的是，我们根据发生CO ₂插入的键的类型组织了这次审查。