Spirofused and Annulated 1,2,4‐Trioxepane‐, 1,2,4‐Trioxocane‐, and 1,2,4‐Trioxonane‐Cyclohexadienones: Cyclic Peroxides with Unusual Ring Conformation Dynamics

2018 ◽  
Vol 57 (42) ◽  
pp. 13770-13774 ◽  
Author(s):  
Angelika Eske ◽  
Sabrina Ecker ◽  
Carolina Fendinger ◽  
Bernd Goldfuss ◽  
Matthis Jonen ◽  
...  
Keyword(s):  
Ring Conformation

Highly nonplanar macrocyclic ring conformation in the crystal structures of Ni(II) and Cu(II) octaphenylporphyrins

2018 ◽  
Vol 59 (2) ◽  
Author(s):  
P. Bhyrappa ◽  
◽  
M. Sankar ◽  
K. Karunanithi ◽  
B. Varghese ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Ring Conformation ◽  
Macrocyclic Ring

scholarly journals The Microwave Spectrum of 3,4-Dihydro-1,2-Pyran

1985 ◽  
Vol 40 (9) ◽  
pp. 913-919
Author(s):  
Juan Carlos López ◽  
José L. Alonso
Keyword(s):  
Dipole Moment ◽  
Excited States ◽  
Ground State ◽  
Principal Axis ◽  
Microwave Spectrum ◽  
Average Intensity ◽  
Ring Conformation ◽  
Vibrationally Excited ◽  
Rotational Constants ◽  
Displacement Measurements

Abstract The rotational transitions of 3,4-dihydro-1,2-pyran in the ground state and six vibrationally excited states have been assigned. The rotational constants for the ground state (A = 5198.1847(24), B = 4747.8716(24) and C = 2710.9161(24) have been derived by fitting μa, μb and μc-type transitions. The dipole moment was determined from Stark displacement measurements to be 1.400(8) D with its principal axis components |μa| =1.240(2), |μb| = 0.588(10) and |μc| = 0.278(8) D. A model calculation to reproduce the ground state rotational constants indicates that the data are consistent with a twisted ring conformation. The average intensity ratio gives vibrational separations between the ground and excited states of the ring-bending and ring-twisting modes of ~ 178 and ~ 277 cm-1 respectively.

Structure and bonding in cyclic phosphoramidates as determined by carbon-13 magnetic resonance

1979 ◽  
Vol 57 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Gerald W. Buchanan ◽  
Frederick G. Morin
Keyword(s):  
Magnetic Resonance ◽  
Nitrogen Atom ◽  
Electron Pair ◽  
Chemical Shifts ◽  
Lone Pair ◽  
Ring Conformation ◽  
Delocalized Electron ◽  
Nitrogen Lone Pair ◽  
Structure And Bonding

13C chemical shifts and 13C–31P couplings are reported for 11 cyclic phosphoramidates of ring sizes from four to nine. Vicinal couplings are compared with those of carbocyclic analogs and provide insight regarding the degree of nitrogen lone pair derealization into the N—P bond. For six-membered and larger rings, there appears to be nearly complete lone pair delocalization, i.e., a trigonal planar nitrogen atom. In azetidine derivatives the nitrogen lone pair remains localized, giving rise to a highly puckered ring conformation. Pyrrolidine derivatives are viewed as having a nitrogen with a partially delocalized electron pair.

scholarly journals SN2 regioselectivity in the esterification of 5- and 7-membered azacycloalkane quaternary salts: a DFT study to reveal the transition state ring conformation prevailing over the ground state ring strain

2014 ◽  
Vol 12 (34) ◽  
pp. 6717-6724 ◽  
Author(s):  
Akihiro Kimura ◽  
Susumu Kawauchi ◽  
Takuya Yamamoto ◽  
Yasuyuki Tezuka
Keyword(s):  
Transition State ◽  
Ground State ◽  
Dft Study ◽  
Ring Conformation ◽  
Ring Strain ◽  
Quaternary Salts

SN2 regioselectivity in 5- and 7-membered azacycloalkanes quaternary salts is directed by the transition state ring conformation.

Über neue monocyclische Acyloxyfluoroborane 2.2.6.6-Tetrafluoro-1.4-dialkyl-1.3.5-trioxa-1.6-diboracyclohexene: Darstellung, Molekül- und Kristallstruktur/ New Monocyclic Acyloxyfluoroboranes 2,2,6,6-Tetrafluoro-1,4-dialkyl-1,3,5-trioxa-2,6-diboracyclohexenes: Synthesis, Molecular and Crystal Structure

1983 ◽  
Vol 38 (5) ◽  
pp. 554-558 ◽  
Author(s):  
Herbert Binder ◽  
Walter Matheis ◽  
Hans-Jörg Deiseroth ◽  
Han Fu-Son
Keyword(s):  
Crystal Structure ◽  
Organic Acid ◽  
Structure Determination ◽  
Unit Cell ◽  
Ring Conformation ◽  
X Ray ◽  
Conformational Isomers ◽  
Ring Group ◽  
Acid Anhydrides

Abstract Acyloxyfluoroboranes Trimeric alkoxydifluoroboranes (F2BOR)3 (2) react with organic acid anhydrides by substitution of a ring group OR forming monocyclic acyloxyfluoroboranes of the type 2,2,6,6-tetrafluoro-l,4-dialkyl-l,3,5-trioxa-2,6-diboracyclohexene (3). The X-ray crystal structure determination of 3a shows two conformational isomers: two planar and two non-planar six-membered rings are present in the unit cell. The ring conformation is influenced by weak intermolecular H — F interactions.

13C−1H Spin-Coupling Constants in the β-d-Ribofuranosyl Ring:  Effect of Ring Conformation on Coupling Magnitudes

1996 ◽  
Vol 118 (6) ◽  
pp. 1413-1425 ◽  
Author(s):  
Carol A. Podlasek ◽  
Wayne A. Stripe ◽  
Ian Carmichael ◽  
Maoyu Shang ◽  
Bidisa Basu ◽  
...  
Keyword(s):  
Coupling Constants ◽  
Spin Coupling ◽  
Ring Conformation ◽  
Spin Coupling Constants ◽  
Ring Effect

E-ring conformation has a key role in cleavable complex formation: homocamptothecin versus camptothecins

2003 ◽  
Vol 651-653 ◽  
pp. 55-65 ◽  
Author(s):  
D Chauvier ◽  
I Chourpa ◽  
M Maizieres ◽  
J.-F Riou ◽  
M Dauchez ◽  
...  
Keyword(s):  
Complex Formation ◽  
Ring Conformation ◽  
Cleavable Complex
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