Electronic excited states of small ring compounds. VII. Bicyclo[2.1.0]pentanes by the photocycloaddition of 1,2,3-triphenylcyclopropene to fumaro- and maleonitrile

1979 ◽  
Vol 57 (9) ◽  
pp. 1037-1049 ◽  
Author(s):  
P. C. Wong ◽  
D. R. Arnold
Keyword(s):  
Excited States ◽  
Charge Transfer Complex ◽  
Nuclear Overhauser Effect ◽  
Small Ring ◽  
Triplet Energy ◽  
Ring Compounds ◽  
Overhauser Effect ◽  
Ca 50 ◽  
Nuclear Overhauser ◽  
Thermal Stability Of

Irradiation of the charge-transfer complex between 1,2,3-triphenylcyclopropene (1) and fumaronitrile (7) and maleonitrile (8) leads to formation of bicyclo[2.1.0]pentane cycloaddition products (9, 10, 11) and the photoene product (12). These products were also formed when the reaction was photosensitized (triplet–triplet transfer). The structure of the adducts was established by analysis of 13C and 1Hmr spectra. Nuclear Overhauser effect studies were also useful. The triplet energies of 7 and 8 (ET ca. 50 kcal mol−1) were determined by studying the photosensitized isomerization as a function of sensitizer triplet energy. The thermal stability of the new bicyclo [2.1.0]pentanes has been studied, particularly with regard to the isomerization resulting from cleavage of the central [0] bond in these strained systems. The mechanism of the photocycloaddition reactions is discussed.

Electronic excited states of small ring compounds. IV. Bicyclo[2.1.0]pentanes by the photocycloaddition of cyclopropenes to olefins

1977 ◽  
Vol 55 (3) ◽  
pp. 393-406 ◽  
Author(s):  
D. R. Arnold ◽  
R. M. Morchat
Keyword(s):  
Excited States ◽  
Nuclear Overhauser Effect ◽  
Dimethyl Fumarate ◽  
Small Ring ◽  
H Nmr ◽  
Ring Compounds ◽  
Overhauser Effect ◽  
Direct Irradiation ◽  
Nuclear Overhauser ◽  
Thermal Stability Of

Direct irradiation of the charge-transfer complex between the cyclopropenes 3,3-dimethyl-1,2-diphenylcyclopropene (3) and 1,2,3-triphenylcyclopropene (7), and the electron deficient olefins dimethyl fumarate (5) and maleic anhydride (11) resulted in formation of the cycloadducts 6, 12–15 which are the bicyclo[2.1.0]pentane derivatives. These products were also formed when the reaction was photosensitized by triplet–triplet transfer. The structure of the adducts rests largely upon the interpretation of 13C and 1H nmr spectra. Nuclear Overhauser effect studies were used to assign stereochemistry. The thermal stability of these new bicyclo[2.1.0]-pentane derivatives has been examined, particularly with regard to the ring-flipping process and the rearrangement to the corresponding cyclopentene derivatives.

1H NMR studies of [N-MeAib1, Tyr(Me)4]ANGII and [N-MeAib1, Tyr(Me)4, Ile8]ANGII in dimethylsulfoxide by nuclear Overhauser effect (NOE) enhancement spectroscopy: cis-trans Isomerism of the His-Pro bond

1990 ◽  
Vol 55 (4) ◽  
pp. 1106-1111 ◽  
Author(s):  
John Matsoukas ◽  
Paul Cordopatis ◽  
Raghav Yamdagni ◽  
Graham J. Moore
Keyword(s):  
1H Nmr ◽  
Nuclear Overhauser Effect ◽  
Nmr Studies ◽  
Restricted Rotation ◽  
Overhauser Effect ◽  
Major Isomer ◽  
Conformational Properties ◽  
Nuclear Overhauser

The conformational properties of the Sarmesin analogues [N-MeAib1, Tyr(Me)4]ANGII and [N-MeAib1, Tyr(Me)4, Ile8]ANGII in hexadeutero-dimethysulfoxide were investigated by Nuclear Overhauser Effect (NOE) Enhancement Studies. Cis-trans isomers (ratio 1 : 6) due to restricted rotation of the His-Pro bond were observed. Interresidue interactions between the His Cα proton and the two Pro Cδ protons revealed that the major isomer was the trans.

scholarly journals Cylindromicin from Arctic-Derived Fungus Tolypocladium sp. SCSIO 40433

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1080
Author(s):  
Imran Khan ◽  
Jing Peng ◽  
Zhuangjie Fang ◽  
Wei Liu ◽  
Wenjun Zhang ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Nuclear Overhauser Effect ◽  
Inhibition Activity ◽  
Tyrosinase Inhibition ◽  
Bioactive Natural Products ◽  
Chemical Structures ◽  
Overhauser Effect ◽  
Spectroscopic Analyses ◽  
Potential Resource ◽  
Nuclear Overhauser

The fungus strain SCSIO 40433 was isolated from an Arctic-derived glacier sediment sample and characterized as Tolypocladium cylindrosporum. A new compound, cylindromicin (1), and seven known secondary metabolites (2–8) were isolated from this strain. The chemical structures of these compounds were elucidated by comprehensive spectroscopic analyses. Cylindromicin (1) featured a 3,4-dihydro-2H-pyran skeleton. The absolute configuration of compound 1 was assigned via interpretation of key Nuclear Overhauser Effect Spectroscopy (NOESY) correlations and Electronic Circular Dichroism (ECD) calculation. Cylindromicin (1) exhibited significant tyrosinase inhibition activity. This study highlights Polar fungi as a potential resource for new bioactive natural products.

The isolation, structure, and stereochemistry of traversiadiene. The precursor hydrocarbon of traversianal biosynthesis

1989 ◽  
Vol 67 (8) ◽  
pp. 1302-1304 ◽  
Author(s):  
Albert Stoessl ◽  
G. L. Rock ◽  
J. B. Stothers
Keyword(s):  
Magnetic Resonance ◽  
Biosynthetic Pathway ◽  
Nuclear Overhauser Effect ◽  
Difference Spectra ◽  
Heteronuclear Correlation ◽  
Magnetic Resonance Studies ◽  
Overhauser Effect ◽  
Effect Difference ◽  
Nuclear Overhauser ◽  
Magnetic Resonance Spectra

A tricyclic diene, traversiadiene, isolated from cultures of Cercosporatraversiana has been shown to have the structure and stereochemistry of the previously postulated hydrocarbon intermediate on the biosynthetic pathway to traversianal (1). Detailed:1H and 13C magnetic resonance studies, including homo- and heteronuclear correlation spectra, led to the gross structure, and the stereochemistry was established through a series of nuclear Overhauser effect difference spectra. Keywords: diterpene, traversiadiene, 1H and 13C magnetic resonance spectra.

scholarly journals Contribution of blood to nuclear Overhauser effect at −1.6 ppm

2021 ◽  
Author(s):  
Jing Cui ◽  
Yu Zhao ◽  
Feng Wang ◽  
Daniel F. Gochberg ◽  
Zhongliang Zu
Keyword(s):  
Nuclear Overhauser Effect ◽  
Overhauser Effect ◽  
Nuclear Overhauser
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