Racemic and Optically Pure Heptahelicene-2-carboxylic Acid: Its Synthesis and Self-Assembly into Nanowire-Like Aggregates
Heptahelicene‐2‐carboxylic acid was effectively synthesised from suitably functionalised naphthalene building blocks. Methoxy‐substituted 1,1′‐ethyne‐1,2‐diylbis(2‐but‐3‐yn‐1‐ylnaphthalene) was cyclised in the presence of CpCo(CO)2/PPh3 to 2‐methoxy‐7,8,11,12‐tetrahydroheptahelicene, which was conve...
Gespeichert in:
Veröffentlicht in: | European Journal of Organic Chemistry 2011-02, Vol.2011 (5), p.853-860 |
---|---|
Hauptverfasser: | , , , , , , , |
Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
Online-Zugang: | Volltext |
Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
Zusammenfassung: | Heptahelicene‐2‐carboxylic acid was effectively synthesised from suitably functionalised naphthalene building blocks. Methoxy‐substituted 1,1′‐ethyne‐1,2‐diylbis(2‐but‐3‐yn‐1‐ylnaphthalene) was cyclised in the presence of CpCo(CO)2/PPh3 to 2‐methoxy‐7,8,11,12‐tetrahydroheptahelicene, which was converted into heptahelicen‐2‐yl trifluoromethanesulfonate. This reactive intermediate underwent Pd(OAc)2/dppp‐catalysed methoxycarbonylation reaction to provide, after hydrolysis, heptahelicene‐2‐carboxylic acid. The racemate was resolved into enantiomers by semipreparative HPLC on a chiral column. The helicity of (+)‐(P)‐heptahelicene‐2‐carboxylic acid was assigned by correlating its CD spectrum to that of the known (+)‐(P)‐heptahelicene. Racemic heptahelicene‐2‐carboxylic acid was deposited on calcite (10‐14) to undergo self‐assembly into nanowire‐like aggregates as demonstrated by noncontact atomic force microscopy (NC‐AFM).
The preparation of racemic as well as nonracemic [7]helicene‐2‐carboxylic acid by [2+2+2] alkyne cycloisomerisation is described. When deposited on a calcite(10‐14) surface, the racemic acid undergoes self‐assembly to nanowire‐like aggregates as demonstrated by NC‐AFM. |
---|---|
ISSN: | 1434-193X 1099-0690 |
DOI: | 10.1002/ejoc.201001110 |