Diastereoselectivity Switch During Alkene Reductions: Diastereodivergent Syntheses of Molecular Fossils via MHAT or Homogeneous Catalytic Hydrogenation Reactions

• Published in: Chemistry : a European journal Vol. 29; no. 20; pp. e202203731 - n/a
• Main Authors: Maior, Christian R. S., Costa, Paulo C. S., Ligiéro, Carolina B. P., Moraes, Lygia S., Sousa, Gustavo R., Lima, Sidney G., Esteves, Pierre M., Miranda, Paulo C. M. L.
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 06.04.2023; Wiley Subscription Services, Inc
• Subjects: Acetic acid; Biomarkers; Carboxylic acids; Chemistry; Chemistry, Multidisciplinary; diastereoselectivity; Fossils; Geology; homogeneous catalytic hydrogenation; hydrogen transfer; Hydrogenation; Isomers; Metal hydrides; Metathesis; molecular fossils; Natural products; olefin cross-metathesis; Physical Sciences; Science & Technology; Stereoselectivity; OLEFIN METATHESIS CATALYSTS; STERANES; MECHANISM; 3-ALKYL; STEREOCHEMISTRY; molecular fossils; diastereoselectivity; homogeneous catalytic hydrogenation; olefin cross-metathesis; MATURATION; ADSORPTION; hydrogen transfer; POTIGUAR BASIN; KINETICS; PETROLEUM MIGRATION
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202203731

Sixteen geosterane derivatives were synthesized in up to 57 % overall yields in four steps harnessing the olefin cross‐metathesis (OCM) and Metal hydride H atom transfer (MHAT) or homogeneous hydrogenation reactions as key steps. Drawing on this strategy, the diastereomeric ratio (d. r.) reached up to 24 : 1 for the thermodynamic isomer and 7 : 1 for the other isomer in the hydrogenation step. In a geological sample from northeast Brazil, we confirmed the putative structures previously assumed as methyl 2‐(3α‐5αH‐cholestan) acetate, methyl 2‐(3β‐5αH‐cholestan)acetate, and methyl 6‐(3β‐5αH‐cholestan)hexanoate, as well three new molecular fossils of approximately 120 million years old. We also proved the migration marking ability of those carboxylic acids derived from forerunner geosteranes during an oil migration event, which suggests their aptitudes as molecular odometers. Our approach demonstrated swiftness and effectiveness in preparing a molecular library of geological biomarkers would also be appropriate to generate stereochemical diversity in molecular libraries for medicinal chemistry and natural product anticipation. Using a diastereoselective and robust strategy we prepared a set of 16 molecular fossils (MF) and confirmed the presence of 6 of them in a 120‐million‐year‐old geological sample. Unlike structural fossils, MF came from soft tissues, and during their (dia)catagenesis they suffer framework and stereochemical modifications exposing their geological history. Such changes and concentration differences helped us to prove an ancient oil migration event.