Supramolecular Photochirogenesis with Carbenes Entrapped in Cyclodextrins

• Published in: European Journal of Organic Chemistry Vol. 2009; no. 34; pp. 5907 - 5912
• Main Authors: Mieusset, Jean-Luc, Wagner, Gerald, Su, Kuan-Jen, Steurer, Marianne, Pacar, Mirjana, Abraham, Michael, Brinker, Udo H.
• Format: Book Review Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.12.2009; WILEY‐VCH Verlag; Wiley; Wiley-VCH
• Subjects: Carbenes; Carbohydrates with 4, 5, 6, ... C atoms, dissacharides and oligosaccharides; Carbohydrates. Nucleosides and nucleotides; Chemistry; Chemistry, Organic; Chiral induction; Cross-disciplinary physics: materials science; rheology; Cyclodextrins; Diazirines; Exact sciences and technology; General and physical chemistry; Heterocyclic compounds; Heterocyclic compounds with several n hetero atoms in the same ring, in separated rings or in fused rings; Materials science; Methods of nanofabrication; Organic chemistry; Photochemistry; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Physical Sciences; Physics; Preparations and properties; Science & Technology; Supramolecular and biochemical assembly; Supramolecular chemistry; INSERTION; PRECURSOR; OXYMERCURATION-DEMERCURATION; INCLUSION COMPLEXES; Cyclodextrins; MECHANISMS; REARRANGEMENTS; Carbenes; C-H BONDS; Supramolecular chemistry; HEMICARCERAND; Chiral induction; Diazirines; PHOTOLYSIS; Encapsulation; Intramolecular reaction; Nitrogen heterocycle; Azine derivatives; Chiral compound; Photochemical reaction; α-Cyclodextrin; Racemic; β-Cyclodextrin; Carbene; Cyclodextrin; Photolysis; Organic free biradical; Enantiomer; Supramolecular structure; Enantiomeric excess; Inclusion compound; Reactor; Dimerization
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.200900899

Two achiral diazirines 1a and 1b have been encapsulated in the inherently chiral cavity of α‐cyclodextrin (6‐Cy), β‐cyclodextrin (7‐Cy) and permethylated β‐cyclodextrin (TRIMEB) and photolyzed. Because of supramolecular photochirogenesis the generated carbenes afford intramolecular C–H insertion products not as a racemate but one enantiomer is slightly favored. With 1a@(6‐Cy)2 the ee of product 7a is doubled. To the best of our knowledge for the first time for carbene reactions, products are imprinted, though modestly, with handedness derived from Cys. The reaction of 1b is highly dependent on the molecular reactor used for inclusion. Whereas 7‐Cy is very efficient for favoring dimerization through azine formation, the use of TRIMEB permits exclusive formation of intramolecular insertion product 7b. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) The outcome of reactions of an entrapped diazirine is highly dependent on the molecular reactor used. While in β‐cyclodextrin azine formation is clearly favored, in the permethylated reactor exclusively intramolecular 1,3‐C–H insertion takes place.Due to supramolecular photochirogenesis of achiral carbene precursors within the chiral cavities, for the first time for carbene reactions one enantiomer of products is slightly favored.