Enzyme Catalytic Promiscuous Reactions In Supercritical Carbon Dioxide

Enzymes are biocatalyst with biocatalytic functions,which have the advantages of high catalytic efficiency,mild reaction conditions,strong specificity,and environmental friendliness,etc.It meets the requirements of atomic economy and green chemistry.However,recent studies have shown that many enzymes appear to play the role of"generalist",whose active sites can catalyze many different chemical reactions.This property is called enzyme catalytic promiscuity.This study mainly explores the application of supercritical carbon dioxide?scCO2?as a reaction medium in enzyme catalytic promiscuous reactions,which has made new contributions to the development of green chemistry,and also expands the application of supercritical carbon dioxide in enzyme catalytic promiscuity.In this work,supercritical carbon dioxide was used as reaction media in the lipase-mediated epoxidation of alkenes for the first time.Under the optimal conditions:alkene?1 mmol?,novozym 435?15 mg?,H₂O₂?50%aqueous solution,1.4 mmol?,n-caprylic acid?0.05 mmol?,40°C,scCO₂?10 MPa,25 mL?,high yields?83–98%?of epoxidation of alkenes could be obtained in a short reaction time.Furthermore,novozym 435 exhibited a satisfactory reusability in the epoxidations.Thus,this work not only presents a green and mild method of lipase-mediated epoxidation with higher yield and reaction rate than other lipase-mediated routes ever reported but also expands the application of supercritical carbon dioxide in enzyme catalytic promiscuity.Aza-Michael addition,a powerful method for the synthesis of?-amino carbonyl derivatives,has been extensively studied in organic chemistry.In this study,the efficient and chemoselective aza-Michael addition of amines to acrylates catalyzed by lipase in supercritical carbon dioxide?scCO₂?was reported for the first time.Under the optimal conditions:amine?1 mmol?,acrylate?1 mmol?,novozym 435?20mg?,40?C,scCO₂?25 mL,10 MPa?,the corresponding Michael adducts of amines to acrylates were exclusively obtained in high yields?60–93%?for a short reaction time?1 h?.It is worth noting that no aminolysis was observed when scCO₂ was used as reaction medium.Moreover,novozym 435 showed high reusability in scCO₂ for aza-Michael addition.In summary,lipase has excellent catalytic ability,chemical selectivity and stability in supercritical carbon dioxide,further indicating that scCO2 has great potential in enzyme catalytic promiscuous reactions.