Novel, intramolecular hydrogen-transfer and cyclo-addition photochemistry of cyclic 1,3-dienes

1991 ◽  
Vol 69 (10) ◽  
pp. 1554-1562 ◽  
Author(s):  
Franciscus W. A. M. Miesen ◽  
Hans C. M. Baeten ◽  
Harm A. Langermans ◽  
Leo H. Koole ◽  
Henk A. Claessens
Keyword(s):  
Hydrogen Transfer ◽  
Membered Ring ◽  
Unsaturated Ketone ◽  
Triplet Excited State ◽  
Hydroxyl Proton ◽  
Conformational Studies ◽  
Rigid System ◽  
H Nmr ◽  
Rearrangement Process ◽  
Intramolecular Hydrogen

With use of one- and two-dimensional NMR spectroscopy and deuterium labelling, the photochemistry of 9-endo-hydroxy-9-exo-vinyl-bicyclo[4.2.1]nonadiene (1) and the 9-exo-(11-dimethylvinyl)- (2) and 9-exo-ethyl- (3) analogues has been studied. Irradiation of 1–3 gave novel 8-membered ring systems 4–6 by a light-induced rearrangement process, in which the hydroxyl proton is transferred on one side of the molecule toward one of the termini of the endocyclic diene. This rearrangement process thus involves a formal hydrogen transfer, during which either H+ or H• may be transferred to a reactive diene intermediate. Replacement of the hydroxyl proton by deuterium in 1–3, and 2H NMR of the corresponding photoproducts, confirmed that the hydrogen translocation occurs intramolecularly. Prolonged irradiation of 4 and 5 results in the formation of pyran products 10 and 11 by an intramolecular photocycloaddition of the triplet excited state of the α,β-unsaturated ketone to 1,3-cis,cis-cyclooctadiene, via a stabilized bisallylic biradical intermediate. Conformational studies of the structurally more rigid system 10, which is derived from 4, revealed that the hydroxyl proton was transferred on the endo side of the molecule. Key words: intramolecular hydrogen transfer, photochemistry of hydroxy-alkyl-bicyclononadienes, intramolecular photocycloaddition, conformational studies.

Stickstoffverbindungen von Elementen der dritten Hauptgruppe mit intra- und intermolekularen Donor-Akzeptor-Bindungen, III [1]. Dynamische Phänomene und Lewis-Säure-Stärke / Nitrogen Compounds of Elements of the Third Main Group with Intra- and Intermolecular Donor Acceptor Bonds, III [1]. Dynamic Phenomena and Lewis Acidity

1987 ◽  
Vol 42 (5) ◽  
pp. 525-535 ◽  
Author(s):  
M. Veith ◽  
A. Belo
Keyword(s):  
Hydrogen Transfer ◽  
Structural Changes ◽  
Mirror Image ◽  
Lewis Acidity ◽  
Temperature Dependent ◽  
Base Interaction ◽  
H Nmr ◽  
Donor Acceptor ◽  
Nmr Techniques ◽  
Intramolecular Hydrogen

Abstract Compounds of the general formula tBuN(H)-SiMe2 -N(tBu)ElX2 (El = B, X = Me (1m), F (1f), Cl (1c); El = AI, X = Me (2m), Cl (2c), Br (2b); El = Ga, X = Me (3m), Cl (3c), Br (3b); El = In, X = Me (4m), Cl (4c), Br (4b); El = Tl, X = Me (5m)) and tBuN(D)-SiMe2-N(tBu)ElMe2 (El = Al (2d), Ga (3d), In (4d)) have been characterized by IR and temperature dependent 1H NMR techniques with respect to their structural changes in solution. A reversible, dynamic, intramolecular equilibrium between two enantiomeric four-membered rings has been established to be responsible for the changes in the spectra. The cyclic form B1, which arises from Lewis acid base interaction of the tert-butyl-amino with the ElX2 group, transforms to the mirror-image B2 via an acyclic intermediate, in which reorientation of the groups by rotation or inversion can take place. In the boron derivatives (1m, 1c, and 1f) no comparable N-B interaction can be detected. The Lewis acidity of the ElX2 group deduced from NH wave numbers increases within the following series: TlMe2<GaMe2≈InMe2<AlMe2<GaBr2≈InBr2<GaCl2≈AlBr2≈InCl2<AlCl2. Intramolecular hydrogen transfer from one nitrogen atom to the other can be excluded by comparison of the rate constant kʜ vs. kᴅ. The free enthalpy of activation Δ G* depends on the acidity of E1X2, the steric requirements and the relative masses of X. The syntheses and characterisation of 1f, 2b, 3b, 4b, 2d, 3d, and 4d are described.

Configurational and conformational studies on condensation products of biogenic amines with 2,5-anhydro-D-mannose

1985 ◽  
Vol 63 (11) ◽  
pp. 2915-2921 ◽  
Author(s):  
Ian M. Piper ◽  
David B. MacLean ◽  
Romolo Faggiani ◽  
Colin J. L. Lock ◽  
Walter A. Szarek
Keyword(s):  
Hydrogen Bond ◽  
Intermolecular Hydrogen Bond ◽  
Direct Methods ◽  
Conformational Studies ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Twist Conformation ◽  
Cell Dimensions ◽  
Internal Hydrogen Bond

The products of a Pictet–Spengler condensation of tryptamine and of histamine with 2,5-anhydro-D-mannose have been studied by X-ray crystallography to establish their absolute configuration. 1(S)-(α-D-Arabinofuranosyl)-1,2,3,4-tetrahydro-β-carboline (1), C16H20N20O4, is monoclinic, P21 (No. 4), with cell dimensions a = 13.091(4), b = 5.365(1), c = 11.323(3) Å, β = 115.78(2)°, and Z = 2. 4-(α-D-Arabinofuranosyl)imidazo[4,5-c]-4,5,6,7-tetrahydropyridine (3), C11H17N3O4, is orthorhombic, P212121 (No. 19), with cell dimensions a = 8.118(2), b = 13.715(4), c = 10.963(3) Å, and Z = 4. The structures were determined by direct methods and refined to R1 = 0.0514, R2 = 0.0642 for 3210 reflections in the case of 1, and to R1 = 0.0312, R2 = 0.0335 for 1569 reflections in the case of 3. Bond lengths and angles within both molecules are normal and agree well with those observed in related structures. In 3 the base and sugar adopt a syn arrangement, which is maintained by an internal hydrogen bond between O(2′) and N(3). The sugar adopts a normal 2T3 twist conformation. The sugar has the opposite anti arrangement in the β-carboline 1 and the conformation of the sugar is unusual; it is close to an envelope conformation with O(4′) being the atom out of the plane. This conformation is caused by a strong intermolecular hydrogen bond from O(5′) in a symmetry-related molecule to O(4′). Both compounds are held together in the crystal by extensive hydrogen-bonding networks. The conformations of the compounds in solution have been investigated by 1H nmr spectroscopy, and the results obtained were compared with those obtained by X-ray crystallography for 1 and 3.

Reductive intramolecular hydrogen transfer in a d8 metal hydride promoted by carbon monoxide addition. An experimental study and its theoretical implications

1984 ◽  
Vol 23 (7) ◽  
pp. 922-929 ◽  
Author(s):  
Franco Cecconi ◽  
Carlo A. Ghilardi ◽  
Paolo Innocenti ◽  
Carlo Mealli ◽  
Stefano Midollini ◽  
...  
Keyword(s):  
Experimental Study ◽  
Carbon Monoxide ◽  
Metal Hydride ◽  
Hydrogen Transfer ◽  
Intramolecular Hydrogen

Chemie polyfunktioneller Moleküle, 108 Tetraedrische Kupfer(I)-Chelatkomplexe der Liganden Bis(diphenylphosphino)amin und Bis(diphenylphosphino)methan / Chemistry of Polyfunctional Molecules, 108 [1] Tetrahedral Copper(I) Chelate Complexes with the Ligands Bis(diphenylphosphino)amine and Bis(diphenylphosphino)methane

1991 ◽  
Vol 46 (12) ◽  
pp. 1699-1705 ◽  
Author(s):  
Jochen Ellermann ◽  
Falk A. Knoch ◽  
Klaus J. Meier
Keyword(s):  
Membered Ring ◽  
Monoclinic Space Group ◽  
Direct Reaction ◽  
Conductivity Data ◽  
Chelate Complexes ◽  
X Ray ◽  
Lattice Constants ◽  
H Nmr ◽  
Highly Strained ◽  
Nitrate Anions

Reaction of [Cu(PPh3)2(NO3)] (1) in acetone with bis(diphenylphosphino)amine (dppa, 2) yields [Cu(dppa)(PPh3)2]+NO3- (3a). [Cu(dppa)(PPh3)2]+PF6- (3b) has been synthesized by metatheses of 3a with NH4PF6. The salt [Cu(dppm)(PPh3)2]+PF6- (5b) has been prepared by an one batch reaction of [Cu(PPh3)2(NO3)] (1), bis(diphenylphosphino)methane (dppm, 4) and NH4PF6 in methanol, because [Cu(dppm)(PPh3)2]+NO3- (5a) could not be isolated by the direct reaction of 1 with 4. The IR, Raman, 31P{1H} NMR, 1H{31Ρ} NMR as well as the conductivity data are reported and discussed together with the X-ray crystal structure of 3a · 1.8 (CH3)2CO. The structure consists of copper atoms coordinated tetrahedrally by two PPh3 ligands and the chelating dppa ligand and features a highly strained four-membered ring. The distorted tetrahedral cations are hydrogen bridged to the nitrate anions. The colourless needles of 3a· 1.8 (CH3)2CO crystallize in the monoclinic space group C 2/c, with the lattice constants a = 4189.2(27); b = 1223.7(8); c = 2717.8(15) pm;β = 113.16(4)°.

Theoretical study on intramolecular hydrogen transfer of 1-methylbutyl peroxide radical

2013 ◽  
Vol 53 (6) ◽  
pp. 431-437 ◽  
Author(s):  
Min Li ◽  
Li-Feng Xie ◽  
Xue-Hai Ju ◽  
Feng-Qi Zhao
Keyword(s):  
Hydrogen Transfer ◽  
Theoretical Study ◽  
Peroxide Radical ◽  
Intramolecular Hydrogen

Synthesis, conformational studies, and inclusion properties of tris[(2-pyridylmethyl)oxy]hexahomotrioxacalix[3]arenes

1998 ◽  
Vol 76 (7) ◽  
pp. 989-996 ◽  
Author(s):  
Takehiko Yamato ◽  
Mitsuteru Haraguchi ◽  
Jun-Ichi Nishikawa ◽  
Seiji Ide ◽  
Hirohisa Tsuzuki
Keyword(s):  
Alkylation Reaction ◽  
Alkali Metal Cations ◽  
Template Effect ◽  
Two Phase ◽  
Conformational Studies ◽  
Preferential Formation ◽  
H Nmr ◽  
Inclusion Properties ◽  
Partial Cone

O-Alkylation of the flexible macrocycle 1 with 2-(chloromethyl)pyridine in the presence of Cs2CO3 resulted in the preferential formation of partial-cone-2. The cone-to-partial-cone ratio of 2 increased in the presence of K2CO3, and led to almost equal in the presence of NaH. The template effect of the alkali metal cations plays an important role in this O-alkylation reaction. The structural characterization of these products is also discussed. The two-phase solvent extraction data indicated that tris[(2-pyridylmethyl)oxy]hexahomotrioxacalix[3]arenes 2 show moderate extractability for n-butylammonium ion and high extractability for Ag+. The 1H NMR titration of cone-2 with AgSO3CF3 clearly demonstrates that a 1:1 complex is formed, which is stable on the NMR time scale. Thus, the synergism of cyclophane moiety and two or three lower-rim side chains with pyridyl groups play a significant role on the complexation of tris[(2-pyridylmethyl)oxy] derivatives cone-2 and partial-cone-2 with Ag+ ion and n-butylammonium ion.Key words: macrocycles, calixarenes, O-alkylation, ionophores, cation-N interaction.

Sign in / Sign up

Export Citation Format

Share Document