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One hundred years of helicene chemistry. Part 2: stereoselective syntheses and chiral separations of carbohelicenes.
MedLine Citation:
PMID:  23151610     Owner:  NLM     Status:  Publisher    
Carbohelicenes generally incorporate a helical, distorted, conjugated, polyaromatic system with ortho-fused benzenoid rings, which is a fundamental molecular characteristic of this class of compounds. They have been described as "molecules in distress" due to their distortion. The generation of a chiral helicity in helicenes was observed because of a severe intramolecular steric strain. Helicity is a molecular necessity in the higher series of carbohelicenes, when at some point, a helical pitch occurs when a second coil is formed. The most interesting properties resulting from such molecular distortion are the very high chiroptical and circular dichroism values. For instance, the resolution of some helicene racemates by "hand picking" of a few homochiral single enantiomeric crystals allowed for a measurement of their optical rotation. Due to that intrinsic chirality spanned over a large polyaromatic template, preliminary results clearly established the efficiency of carbohelicenes to induce asymmetry and chirality in organic synthesis and in supramolecular chemistry. Additionally, they have some potential uses in several fields: materials science, nanoscience, chemical biology and supramolecular chemistry. It has encouraged many attempts to develop new asymmetric syntheses of carbohelicenes, as well as some chiral separations of enantiomers and diastereoisomers. This review is thus dedicated to carbohelicene chirality. It gathered a substantial collection of data, and a comprehensive review on the preparations of enantioenriched helicenes, either from an asymmetric synthesis or from a chiral separation. Utilizations of non-racemic helicenes and their applications will be treated in the following review (Part 3), and will not be the subject of this manuscript.
Marc Gingras; Guy Félix; Romain Peresutti
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-11-15
Journal Detail:
Title:  Chemical Society reviews     Volume:  -     ISSN:  1460-4744     ISO Abbreviation:  Chem Soc Rev     Publication Date:  2012 Nov 
Date Detail:
Created Date:  2012-11-15     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0335405     Medline TA:  Chem Soc Rev     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
CNRS, UMR CNRS 7325, CINaM, 163 ave. de Luminy, 13288 Marseille, France.
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