Sustainable O-formylation of alcohols using CO2 as C1 building block

GABRIELA GASTELU; JORGE G. URANGA

Venecia

Otro; ONLINE GREEN CHEMISTRY POSTGRADUATE SUMMER SCHOOL; 2020

Green Sciences for Sustainable Development Foundation

Valorization of CO2 is receiving a considerable attention in green chemistry as a C1 building block in organic synthesis because it is abundant, non-toxic and renewable [1]. Its capture and activation are the most challenging step due to its stability and inertness. Borohydride is an interesting reducing agent which is capable of capture and reduce three molecules of CO2 per reductant molecule in mild conditions [2]. Although H2 shows the most favorable atom economy, borohydride is easier to handle and thus, the process doesn?t need high pressure conditions becoming a less risky methodology.The reaction of CO2 and borohydride results in triformoxyborohydride, a compound already described as formylating and methylating agent of amines [3], [4]. However, the O-formylation of alcohols from CO2 hasn?t been widely explored yet, as only a few examples were described [5]. As alcohols are widely present in biomass derivatives, the interest of this reaction is based on the synthesis of value-added products from both, biomass and CO2, carbon renewable sources. The produced formates are considered valuable compounds in industry [6]. In addition, formate group can be used as a protective or an activating group for further reactions. In this project, CO2 was activated using NaBH4 through an adaption of a methodology previously described in literature [3]. Triformoxyborohydride (-BH(OCHO)3) was obtained and lately used to formylate different alcohols, which included renewable alcohols. The hole process is described in figure 1. Good to excellent yields were obtained for the formate esters synthesis. In conclusion, a sustainable and simple methodology for O-formylation of alcohols using CO2 as C1 building block was developed. Formate esters are will be useful intermediaries to promote further reactions.