Tandem catalysis: a new approach to polypeptides and cyclic carbonates

Abstract

A new tandem catalytic system mediates very efficiently and selectively at room temperature two sequential reactions to produce relevant derivatives in one pot. Remarkably, this new concept of catalysis allows the facile synthesis of polypeptides and provides direct access to cyclic carbonates in high yields, through the incorporation of the carbon dioxide released from the initial step, thus achieving full-atom economy.

Aluminum‐Catalyzed One‐Pot Synthesis of Polyester‐b‐Polypeptide Block Copolymers by Ring‐Opening Polymerization

“…As depicted in Figure , the formation of the mono(alkoxide) species (salen)Al(OR) resulting from the insertion of PO into an AlCl bond can occur, similarly to what was reported in the PO/CO 2 copolymerization or in the ROP of NCAs . Although we demonstrated that the mono(alkoxide) species is efficient for NCA polymerization, neutral aluminum alkoxide derivatives are inactive at room temperature for the ROP of lactide.…”

“…The high polymerization activities observed with the salen aluminum complex Al ‐ 1 ( Figure ) led us to use the same reaction conditions for the ring‐opening copolymerization of NCA and rac ‐LA . Therefore, the catalytic system was pre‐activated in the presence of 2 eq.…”

“…In our search for new (co)polymerization catalysts, we focused our efforts on investigating the catalytic activity of salen aluminum catalysts known to effect both of the productive steps of polypeptide synthesis and polylactide formation . Therefore, we decided to study the potential of such a catalytic system in a copolymerization procedure, aiming to produce polypeptide‐polylactide block copolymers with a one‐pot methodology.…”

Waste not, want not: CO2 (re)cycling into block polymers

“…22,23 In pioneering earlier work, Thomas and co-workers demonstrated that N-carboxyanhydride ROP could be used to produce polypeptides and the released CO 2 was subsequently used to make cyclic carbonates via tandem catalysis. 24 Inspired by this intriguing recycling opportunity and with polymerisation catalysts in hand known to operate under low CO 2 pressures, 22,23 we envisaged a single catalyst could be used in a switchable process to deliver block polymer product (Scheme 1).…”

Polyoxometalate-based homochiral metal-organic frameworks for tandem asymmetric transformation of cyclic carbonates from olefins

“…Recently, the selective and efficient conversion of light olefins with CO 2 as a C 1 building block into value-added enantiomerically pure cyclic carbonates has attracted great interest from chemists and governments due to its tremendous potential economic and environmental impact, especially considering the increasing worldwide greenhouse effect 1 . The general synthetic procedure includes two mechanistically distinct catalytic processes consisting of the asymmetric epoxidation of olefins, based on the research of Sharpless and others, and the asymmetric coupling epoxide with CO 2 (refs 2 , 3 , 4 , 5 ).…”