Stereochemical assignment of 2-amino-1,2,3,4-tetrahydro-1-naphthalenols via oxazolidin-2-one derivatives

1987 ◽  
Vol 65 (4) ◽  
pp. 868-872 ◽  
Author(s):  
Antonio Delgado ◽  
David Mauleon ◽  
Cristina Minguillon ◽  
Miguel Feliz ◽  
Miquel A. Pericas ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chair Conformation ◽  
Stereochemical Assignment ◽  
Magnetic Resonance Data ◽  
Nuclear Magnetic Resonance Spectra ◽  
Conformationally Restrained ◽  
Cis And Trans ◽  
Theoretical Results ◽  
Nuclear Magnetic

The stereochemical assignment of cis- and trans-2-amino-1,2,3,4-tetrahydro-1-naphthalenols (1) can be performed by means of their conformationally restrained tricyclic tetrahydronaphtho[2,1-d]oxazol-2-one derivatives 2–6. Thus, 1H and 13C nuclear magnetic resonance data of compounds 2–6 reveal differences between the cis and trans stereoisomers that are independent of the nature and number of the aromatic substituents. Conformational analysis of compounds 2–6 has been performed from the LAOCOON/3 analysis of their nuclear magnetic resonance spectra and MNDO theoretical results, through the use of the Karplus–Altona equation. Whereas the trans compounds exist in a rigid half-chair conformation, a 1:1 equilibrium of two interconverting half-chair conformers is found for the cis derivatives.

Conformation of the C15 lupine alkaloids

1967 ◽  
Vol 45 (13) ◽  
pp. 1447-1457 ◽  
Author(s):  
M Wiewiorowski ◽  
O E Edwards ◽  
M D Bratek-Wiewiorowska
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Mercuric Acetate ◽  
Lone Pair ◽  
Chair Conformation ◽  
Boat Conformation ◽  
Acid Complex ◽  
Nuclear Magnetic Resonance Spectra ◽  
The Difference ◽  
Nuclear Magnetic

Methods have been developed for preparing 17α-deuterio-, 17β-deuterio-, and l7-dideuteriolupanines. The nuclear magnetic resonance and infrared spectra of these provided strong evidence that ring C in the alkaloid is in a boat conformation in solution. Reduction of these compounds to the deuterated sparteines confirmed the same geometry for sparteine. In contrast, moilodeuteration of aphylline at C-17 showed that i t had an all-chair conformation in solution. 13β-Hydroxylupanine was shown to have the same conformation as lupanine in solution, but to adopt an all-chair conformation in the solid state. Interpretation of the nuclear magnetic resonance spectra enabled the conformation of ring C of 15-oxosparteine to be assigned. The oxidation and reductions involving C-17 of lupanine have been shown to be highly stereospecific, and an interpretation is given of the difference betmeen the dehydrogenation of lupanine by mercuric acetate and those by Nbromosuccinimide or by the mercuric acetate - ethylenediatninetetraacetic acid complex. It has now been found that the C—H stretching “trans bands” in the infrared are evident when only one hydrogen is alpha to the basic nitrogen and in an antiparallel relation to the lone pair of electrons.

The nuclear magnetic resonance spectra and stereochemistry of 4-Benzoyloxy-1-thiaflavans

1967 ◽  
Vol 20 (10) ◽  
pp. 2235 ◽  
Author(s):  
GF Katekar ◽  
AG Moritz
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Double Resonance ◽  
Heterocyclic Ring ◽  
Coupling Constants ◽  
Spectral Parameters ◽  
Nuclear Magnetic Resonance Spectra ◽  
Cis And Trans ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

The nuclear magnetic resonance spectra of cis- and trans-4-benzoyloxy- 1-thiaflavan in deuterochloroform have been investigated at 60 Mc/s. The spectral parameters for the heterocyclic ring protons have been obtained by analysis of the frequency-sweep double-resonance spectra and verified by an iterative technique using a digital computer. Long- range coupling constants were observed between the protons at C 4 and C 5 (J 0.8 c/s) and between the protons at C 2 and C 4 (J 0.2 c/s) for the cis isomer.

Nuclear magnetic resonance spectra of 2-pyrazolines

1968 ◽  
Vol 46 (5) ◽  
pp. 810-812 ◽  
Author(s):  
Wallace S. Brey Jr. ◽  
Carmen M. Valencia
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Phenyl Group ◽  
Coupling Constants ◽  
Spectral Parameters ◽  
Vicinal Coupling Constants ◽  
Nuclear Magnetic Resonance Spectra ◽  
Rigid Conformation ◽  
Cis And Trans ◽  
Nuclear Magnetic

The nuclear magnetic resonance spectral parameters for a series of 3-carbomethoxy-2-pyrazolines are presented and discussed. Substitution of a phenyl group at position-5 has a large effect on the relative chemical shift of the two protons at position-4, although a carbomethoxy group at position-5 has little effect. The cis and trans vicinal coupling constants in compounds with two protons in position-4 are nearly equal and differ from the values found when there is a substituent in position-4. The presence of three groups in positions-4 and -5 appears to hold the ring in a rigid conformation. The line width for the hydrogen attached to nitrogen depends upon the number of phenyl groups in position-5.

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