39555-34-5Relevant articles and documents
Photoelimination of nitrogen from adamantane and pentacycloundecane (PCU) diazirines: A spectroscopic study and supramolecular control
?umanovac, Tatjana,Ale?kovi?, Marija,?ekutor, Marina,Matkovi?, Marija,Baron, Thibaut,Mlinari?-Majerski, Kata,Bohne, Cornelia,Basari?, Nikola
, p. 1806 - 1822 (2019/07/16)
Photochemical reactivity of pentacycloundecane (PCU) and adamantane diazirines was investigated by preparative irradiation in different solvents, laser flash photolysis (LFP) and quantum chemical computations. In addition, formation of inclusion complexes for diazirines with cucurbit[7]uril, β- and γ-cyclodextrin (β- and γ-CD) was investigated by 1H NMR spectroscopy, isothermal microcalorimetry and circular dichroism spectroscopy, followed by the investigation of photochemical reactivity of the formed complexes. Diazirines undergo efficient photochemical elimination of nitrogen (ΦR > 0.5) and deliver the corresponding singlet carbenes. Singlet carbenes react in intra- and intermolecular reactions and we found a rare singlet carbene pathway in CH3OH involving protonation and formation of a carbocation, detected due to the specific rearrangement of the pentacycloundecane skeleton. Singlet diazirines undergo intersystem crossing and deliver triplet carbenes that react with oxygen to form ketones which were isolated after irradiation. Our main finding is that the formation of diazirine inclusion complexes with β-CD and γ-CD changes the relative ratio of singlet vs. triplet pathways, with singlet carbene products being dominant from the chemistry of the irradiated complexes. Our combined theoretical and experimental studies provide new insights into the supramolecular control of carbene reactivity which has possible applications for the control of product distribution by solvent effects and the choice of constrained media.
Carbenes in constrained systems. 2. First carbene reactions within zeolites - Solid state photolysis of adamantane-2-spiro-3′-diazirine
Kupfer, René,Poliks, Mark D.,Brinker, Udo H.
, p. 7393 - 7398 (2007/10/02)
Inclusion complexes of adamantane-2-spiro-3′-diazirine (1) in different X- and Y-type zeolites (faujasite) have been prepared. These complexes were analyzed by FT-IR and 13C CP-MAS NMR spectroscopy. The guest-host complexes were irradiated with UV light in the solid state and the reaction products separated from the host and analyzed. Product ratios obtained in zeolites are totally different from those obtained by irradiation of 1 in solution or as a pure compound. In zeolites the main products isolated are 2,4-dehydroadamantane (4) and 2-adamantanol (6). In addition, adamantanone (5) and adamantane are formed. While 2-adamantanol (6) is thought to be a product from an acid-catalyzed reaction, the strained 2,4-dehydroadamantane (4) derives from an intramolecular 1,3 C-H insertion of adamantanylidene (3). In stark contrast to reactions in solution, in zeolites the formation of adamantanone azine (7) resulting from an intermolecular reaction is only of minor significance.
