Three component coupling of amines, alkyl halides and carbon dioxide: An environmentally benign access to carbamate esters (urethanes)

Carbamate esters represent an important class of compounds showing a wide range of interesting biological properties. Such compounds exhibit anti-cancer, anti-HIV, anticonvulsant, antiretroviral, anti-nociceptive, anti-inflammatory, anti-Alzheimer, and antibiotic properties. Moreover, these compounds have many applications in the area of synthetic organic chemistry. Consequently, considerable efforts have devoted to the development of efficient and practical synthetic routes to these useful compounds. However, common preparations leading to these target compounds are limited by requiring toxic reagents such as phosgene, its derivatives, or isocyanates. Synthesis of titled compounds employing CO2 as a clean and safe carbonyl reagent in place of toxic phosgene or isocyanates has attracted considerable attention in recent years. In this mini-review we will highlight the most important developments on the synthesis of carbamate esters through the carboxylative coupling of amines with alkyl halides and CO2 by hoping that it will stimulate researchers to develop new and improved methods for the synthesis of these biologically and synthetically important compounds with sustainable chemistry and Green Chemistry perspectives.