- Heavy-Atom Tunneling Processes during Denitrogenation of 2,3-Diazabicyclo[2.2.1]hept-2-ene and Ring Closure of Cyclopentane-1,3-diyl Diradical. Stereoselectivity in Tunneling and Matrix Effect
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Triplet cyclopentane-1,3-diyl diradical (T-DR) was generated via photolysis of 2,3-diazabicyclo[2.2.1]hept-2-ene (AZ) under low-temperature matrix conditions. Temperature independency of T-DR decay and the kinetic isotope effect of T-DR-d6 provided experimental evidence in favor of heavy-atom (carbon) tunneling process during the decay of T-DR to bicyclo[2.1.0]pentane (CP) via singlet S-DR. For the first time, the formation of CP was confirmed using low-temperature infrared spectra. Computations of the heavy-atom tunneling process using the small-curvature tunneling method demonstrated a fast reaction from S-DR to CP. Moreover, we observed heavy-atom tunneling during denitrogenation of AZ. Stereoselectivity in the tunneling process of T-DR-d6 was observed at 7 K to form retention-CP-d6 in higher amounts compared to inversion-CP-d6. Photolysis of AZ-d6 yielded inv-CP-d6 and ret-CP-d6 in environment- and temperature-dependent ratios. Moreover, because of the prominent matrix effect, T-DR decayed more rapidly in Ar than in glassy organic matrices.
- Sarkar, Sujan K.,Solel, Ephrath,Kozuch, Sebastian,Abe, Manabu
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- An exclusive approach to 3,4-disubstituted cyclopentenes and alkylidene cyclopentenes via the palladium catalyzed ring opening of azabicyclic olefins with aryl halides
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A simple and efficient method for the stereoselective ring opening of bicyclic hydrazines with various aryl halides under palladium catalysis has been elaborated. The reactions afforded trans-3,4-disubstituted cyclopentenes or alkylidene cyclopentenes in good to excellent yields. By taking advantage of multiple points of functionalization in the synthesized trans-3-phenyl-4- hydrazino-cyclopentene, we have synthesized the antidepressant Cypenamine (trans-2-phenylcyclopentylamine).
- Joseph, Nayana,Rajan, Rani,John, Jubi,Devika,Chand, S. Sarath,Suresh,Pihko, Petri M.,Radhakrishnan
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- Ring-opening cross metathesis of 1,3-cyclopentadiene-heterodienophile cycloadducts to produce cyclic hydrazines and hydroxylamines
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The combination of a hetero-Diels-Alder reaction of a N-N or N-O heterodienophile and 1,3-cyclopentadiene with ruthenium catalyzed ring-opening cross metathesis (ROCM) produces new functionalized heterocyclic five-membered rings. The cycloadduct of 1,3-cyclopentadiene and diethyl azidodicarboxylate underwent ROCM to give a 2.5:1 (E:Z) mixture of diastereomeric cyclic hydrazines. This substrate also appears to be a suitable precursor for ring-opening polymerization. The cycloadduct of 1,3-cyclopentadiene and an acyl nitroso compound underwent ROCM to give a mixture of four cyclic hydroxylamines. These results represent the first examples of ROCM on strained cyclic substrates containing multiple heteroatoms.
- Ellis, J.Michael,King, S.Bruce
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- Enantioselective desymmetrization of meso bicyclic hydrazines: A novel approach to the asymmetric synthesis of polysubstituted amino cyclopentanic cores
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Catalytic asymmetric hydroboration can be successfully applied to meso bicyclic hydrazines. The resulting alcohols are of great synthetic interest and can lead in a straightforward manner to cyclopentanic diamino alcohols with good enantiomeric purity.
- Perez Luna,Ceschi,Bonin,Micouin,Husson,Gougeon,Estenne-Bouhtou,Marabout,Sevrin,George
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p. 3522 - 3524
(2007/10/03)
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- Diazo-compounds in heterocyclic synthesis. Aziridine ring expansion in a retro-Diels-Alder reaction
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Hydrolysis and decarboxylation of exo-diethyl 3-phenyl-3,6,7- triazatricyclo[3,2,1,02,4]octane-6,7-dicarboxylate followed by mild oxidation gives N-phenyl-1,4-dihydropyridine (50-70%), thus affording a simple route for the conversion of cyclopentadiene into 1,4-dihydropyridines.
- Horwell,Deyrup
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p. 485 - 486
(2007/10/07)
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