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Asymmetric Synthesis of Nonracemic 2-Amino[6]helicenes and Their Self-Assembly into Langmuir Films
- Alternative ways of preparing nonracemic 2-amino[6]helicene derivatives were explored. The enantioselective [2 + 2 + 2] cycloisomerization of a nonchiral triyne under Ni(cod)(2)/(R)-QUINAP catalysis delivered the enantioenriched (+)-(P)-2-aminodibenzo[6]helicene derivative in 67% ee. An ultimate "point-to-helical" chirality transfer was observed in the cyclization of enantiopure triynes mediated by Ni(CO)(2)(PPh3)(2) affording (-)-(M)- or (+)-(P)-7,8-bis(p-tolyl)hexahelicen-2-amine in >99% ee as well as its benzoderivative in >99% ee. The latter mode of stereocontrol was inefficient for a 2-aminobenzo[6]helicene congener with an embedded five-membered ring. The rac-, (-)-(M)-, and (+)-(P)-7,8-bis(p-tolyl)hexahelicen-2-amines formed Langmuir monolayers at the air water interface featuring practically identical surface pressure vs mean molecular area isotherms. The corresponding Langmuir-Blodgett films on quartz or silicon substrates were characterized by UV vis/ECD spectroscopy and AFM microscopy, respectively.
Author details: | Manfred KarrasORCiDGND, Jan Holec, Lucie Bednarova, Radek Pohl, Bernd SchmidtORCiDGND, Irena G. Stara, Ivo StaryORCiD |
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DOI: | https://doi.org/10.1021/acs.joc.8b00538 |
ISSN: | 0022-3263 |
ISSN: | 1520-6904 |
Pubmed ID: | https://pubmed.ncbi.nlm.nih.gov/29676572 |
Title of parent work (English): | The journal of organic chemistry |
Publisher: | American Chemical Society |
Place of publishing: | Washington |
Publication type: | Article |
Language: | English |
Date of first publication: | 2018/05/18 |
Publication year: | 2018 |
Release date: | 2021/11/30 |
Volume: | 83 |
Issue: | 10 |
Number of pages: | 16 |
First page: | 5523 |
Last Page: | 5538 |
Funding institution: | Czech Science FoundationGrant Agency of the Czech Republic [16-08294S]; Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences [RVO: 61388963]; German Academic Exchange Service (DAAD-fellowship) [57314603]; Ministry of Education, Youth and Sports of the Czech RepublicMinistry of Education, Youth & Sports - Czech Republic [LM2015073] |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Chemie |
DDC classification: | 5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften |
Peer review: | Referiert |