1,4-Cycloheptadienes: preparation and comparison of their proton magnetic resonance spectra with those of the corresponding cycloheptatrienes

1977 ◽  
Vol 55 (2) ◽  
pp. 251-258 ◽  
Author(s):  
Ivan Pikulik ◽  
Ronald F. Childs
Keyword(s):  
Magnetic Resonance ◽  
Good Yield ◽  
Proton Magnetic Resonance ◽  
Copper Complexes ◽  
Ring Current ◽  
Catalytic Reduction ◽  
Azo Compounds ◽  
Pmr Spectra ◽  
Basic Hydrolysis ◽  
Hydrolysis Of

A general route to 3-substituted cyclohepta-1,4-dienes is described in this paper. 7-Substituted cycloheptatrienes were used as starting materials and these were reacted with 4-phenyl-1,2,4-triazoline-3,5-dione to give 4 + 2 cycloaddition products of the norcaradiene form of the cycloheptatrienes. Catalytic reduction of these adducts gave 9-substituted 4-phenyl-2,4,6-triazatetracyclo[5.3.2.02,6.08,10]dodeca-3,5-diones in good yield. Basic hydrolysis of the hetero-cyclic ring of these products followed by Cu2+ oxidation of the resulting hydrazo compounds gave the copper complexes of substituted 6,7-diazatricyclo[3.2.2.02,4]non-6-enes. The azo compounds, formed on decomplexation of the copper complexes, readily lost nitrogen to give 3-substituted cyclohepta-l,4-dienes. Care had to be taken during these last steps as the cyclo-heptadienes with carboxylate substituents very readily isomerized to the conjugated isomers. The pmr spectra of the cyclohepta-l,4-dienes and related cycloheptatrienes are compared and discussed in terms of the presence of an induced diamagnetic ring current in the latter systems.

scholarly journals The Proton Magnetic Resonance Spectrum of 15N-Pyrrole

1969 ◽  
Vol 24 (12) ◽  
pp. 2004-2009 ◽  
Author(s):  
Erkki Rahkamaa
Keyword(s):  
Spectral Analysis ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Spin System ◽  
Proton Magnetic Resonance ◽  
Resonance Spectrum ◽  
Proton Magnetic Resonance Spectrum ◽  
Proton Proton ◽  
Pmr Spectra

AbstractA sub-spectral analysis of the high resolution proton magnetic resonance spectrum of 15N-pyrrole has been performed as an AA'BB'CX spin system. Absolute values of the proton-proton and nitrogen-proton couplings have been determined. It has also been concluded that all three nitrogen-proton couplings are negative. The parameters found in the analysis of the PMR spectra of normal and deuterated pyrroles, have also been briefly reported.

scholarly journals Changes in proton-magnetic-resonance spectra during aminolysis and enzymic hydrolysis of cephalosporins

1970 ◽  
Vol 116 (3) ◽  
pp. 385-395 ◽  
Author(s):  
J. M. T. Hamilton-Miller ◽  
Eva Richards ◽  
E. P. Abraham
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Structural Changes ◽  
Ring Structure ◽  
Reaction Products ◽  
Enzymic Hydrolysis ◽  
Lactam Ring ◽  
Group 5 ◽  
Hydrolysis Of ◽  
Magnetic Resonance Spectra

1. Changes in proton-magnetic-resonance spectra were followed during the reaction of cephalosporins, deacetylcephalosporins, deacetoxycephalosporins and a Δ2-cephalosporin with ND3 in D2O. 2. Changes in proton-magnetic-resonance spectra were also followed during the hydrolysis of a cephalosporin and a deacetylcephalosporin in D2O with a β-lactamase. 3. Structures for the reaction products are proposed. 4. The signals obtained after aminolysis of the β-lactam ring of a cephalosporin indicate that the reaction is accompanied by expulsion of the acetoxy group as acetate, formation of a double bond in the Δ4-position and the appearance of an exocyclic methylene group. 5. Aminolysis of deacetyl- and deacetoxycephalosporins can occur without immediate structural changes in the dihydrothiazine ring. 6. In contrast, the ring structure of the first product of enzymic hydrolysis of a deacetylcephalosporin is apparently identical with that of the product of aminolysis of the cephalosporin itself.

METHANOLYSIS OF CARBOHYDRATE ORTHOACETATES

1963 ◽  
Vol 41 (3) ◽  
pp. 555-561 ◽  
Author(s):  
A. S. Perlin
Keyword(s):  
Magnetic Resonance ◽  
Spectral Data ◽  
Methyl Ether ◽  
Proton Magnetic Resonance ◽  
Acyl Migration ◽  
Acetate Group ◽  
Marked Contrast ◽  
Aqueous Acid ◽  
Acid Methanolysis ◽  
Hydrolysis Of

Acid methanolysis of D-mannose 1,2-(methyl orthoacetate) 3,4,6-triacetate (I) yields mainly 3,4,6-tri-O-acetyl-D-mannose (II). D-glucose 1,2-(ethyl orthoacetate) 3,4,6-triacetate (VIII) yields 3,4,6-tri-O-acetyl-D-glucose and methyl 3,4,6-tri-O-acetyl-β-D-glucopyranoside. The rate of methanolysis of II differs little from that of VIII, in marked contrast to the relative rates of hydrolysis of these compounds in aqueous acid. Several concurrent reactions appear to take place in methanol initiated by protonation at different positions on the orthoester ring.During isolation, II is converted partially to 2,4,6-tri-O-acetyl-D-mannose (VI), a novel instance of acyl migration in the sugar series. Structural assignments for these two triacetates are based on chemical and proton magnetic resonance spectral data. The 2-acetate group of VI migrates during methylation, both II and VI yielding the same 2-O-methyl ether.

The hydrolysis of (π-C6H6)Cr(π-C6F5CO2C2H5): an unexpected decarboxylation

1986 ◽  
Vol 64 (6) ◽  
pp. 1170-1172 ◽  
Author(s):  
Michael J. McGlinchey ◽  
Hao Nguyen
Keyword(s):  
Carboxylic Acid ◽  
Good Yield ◽  
Compound C ◽  
Sandwich Compound ◽  
Basic Hydrolysis ◽  
Hydrolysis Of

The attempted basic hydrolysis of the ester sandwich compound (C6H6)Cr(C6F5CO2Et) did not yield the expected carboxylic acid but instead produced (C6H6)Cr(C6F5H) in good yield together with traces of (C6H6)Cr(C6HF4OMe). Attempts to trap a benzyne intermediate were unsuccessful and the mechanism of decarboxylation is discussed in terms of internal chelation at the chromium centre.

scholarly journals The Interaction between Pyrimidine Nucleosides and Benzene in Aqueous Solution, studied by Proton Magnetic Resonance

1972 ◽  
Vol 27 (10) ◽  
pp. 1196-1201 ◽  
Author(s):  
H.-D. Lüdemann
Keyword(s):  
Aqueous Solution ◽  
Magnetic Resonance ◽  
Aqueous Solutions ◽  
Proton Magnetic Resonance ◽  
Pyrimidine Nucleosides ◽  
Pmr Spectra

Changes caused in the PMR spectra of aqueous solutions of four pyrimidine nucleosides (uridine, deoxyuridine, cytidine and thymidine) containing benzene (0.12 molal) by the variation of concentration and temperature have been investigated. From the data obtained, the participation of the benzene molecules in the stacking of the nucleosides is deduced.

Sign in / Sign up

Export Citation Format

Share Document