Enantioselective ene‐reduction of E‐2‐cyano‐3‐(furan‐2‐yl) acrylamide by marine and terrestrial fungi and absolute configuration of (R)‐2‐cyano‐3‐(furan‐2‐yl) propanamide determined by calculations of electronic circular dichroism (ECD) spectra

• Published in: Chirality (New York, N.Y.) Vol. 31; no. 7; pp. 534 - 542
• Main Authors: Jimenez, David E.Q., Barreiro, Juliana C., Santos, Fernando M., Vasconcellos, Suzan P., Porto, André L.M., Batista, João M.
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01-07-2019
• Subjects: Absolute configuration; Acrylamide; Aspergillus; biocatalysis; Biotransformation; Chemical synthesis; Circular dichroism; Configurations; Density functional theory; Dichroism; electronic circular dichroism; Enantiomers; enoate reductase; Fungi; Knoevenagel condensation; marine‐ and terrestrial‐derived fungi; Mathematical analysis; Microorganisms; Microwave radiation; Microwaves; Organic chemistry; Penicillium citrinum; Reduction; Terrestrial environments; Time dependence; enoate reductase; electronic circular dichroism; marine- and terrestrial-derived fungi; Knoevenagel condensation; biocatalysis
• ISSN: 0899-0042; 1520-636X
• DOI: 10.1002/chir.23078

This work reports the green organic chemistry synthesis of E‐2‐cyano‐3(furan‐2‐yl) acrylamide under microwave radiation (55 W), as well as the use of filamentous marine and terrestrial‐derived fungi, in the first ene‐reduction of 2‐cyano‐3‐(furan‐2‐yl) acrylamide to (R)‐2‐cyano‐3‐(furan‐2‐yl)propanamide. The fungal strains screened included Penicillium citrinum CBMAI 1186, Trichoderma sp. CBMAI 932 and Aspergillus sydowii CBMAI 935, and the filamentous terrestrial fungi Aspergillus sp. FPZSP 146 and Aspergillus sp. FPZSP 152. A compound with an uncommon CN‐bearing stereogenic center at the α‐C position was obtained by enantioselective reactions mediated in the presence of the microorganisms yielding the (R)‐2‐cyano‐3‐(furan‐2‐yl) propanamide 3a. Its isolated yield and e.e. ranged from 86% to 98% and 39% to 99%, respectively. The absolute configuration of the biotransformation products was determined by time‐dependent density functional theory (TD‐DFT) calculations of electronic circular dichroism (ECD) spectra. Finally, the tautomerization of 2‐cyano‐3‐(furan‐2‐yl) propanamide 3a to form an achiral ketenimine was observed and investigated in presence of protic solvents.