Photocycloaddition of chalcones to yield cyclobutyl ditopic cyclophanes

Cibin, Francesca R; Bello, Nicoletta Di; Doddi, Giancarlo; Fares, Vincenzo; Mencarelli, Paolo; Ullucci, Elio

doi:10.1016/j.tet.2003.10.026

Cited by 20 publications

(6 citation statements)

References 23 publications

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“…The chemical shifts of these protons are very close, and their identification from usual 1 H NMR spectra is difficult. The unambiguous assignment of 1 H and 13 C signals was performed using 2D [1][2][3][4][5][6][7][8][9][10][11][12][13] In the 13 C NMR spectra, the signals for the olefinic carbon atoms differ significantly in the chemical shifts: δ C α ≈ 122 and δ C β ≈ 139, which makes it possible to identify the corresponding protons by the 2D HSQC data (see Table 1). This assignment is also confirmed by the results of 2D HMBC experiments in which the cross peaks between the nuclei pairs H(6)-C(β) and H(β)-C(2) are observed.…”

Section: Resultsmentioning

confidence: 99%

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Photochemical transformations of chalcone-podands into cyclobutane-containing benzocrown ethers

et al. 2009

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A method for the synthesis of cyclobutane containing benzocrown ethers by the template photocycloaddition of the corresponding chalcone podands in solutions was developed. It was shown by X ray diffraction analysis, 1 H and 13 C NMR, and UV spectroscopy that the intra molecular [2π+2π] photocycloaddition (PCA) is stereoselective with the predominant forma tion of structures of the β and γ truxinic type. The PCA rate was shown to depend on the size of the oxyethylene spacer and stereoorientation of the chalcone fragments in the podands. The selectivity of the PCA process can be controlled by a change in the concentration of the template (alkaline metal ions) and variation of the wavelength range of irradiation.

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Section: Resultsmentioning

confidence: 99%

“…5). The maximum deviations from the planar geometry of the cyclobutane fragment (7) 1.549 (2) С (3)-С(5)-С (7) 89.4(9) С(7)-С (8) 1.546 (2) (9) are characteristic of rtcc isomers 3b and 3c; the angle ϕ is 23.3° (C(9)C(8)C(27)/C(9)C(26)C (27)) and 29.1°( C(28)C(29)C(8)/C(28)C(9)C(8)), respectively (see Fig. 4).…”

Section: Methodsmentioning

confidence: 99%

Photochemical transformations of chalcone-podands into cyclobutane-containing benzocrown ethers

et al. 2009

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“…In addition, the coupling pattern of H-2 and H-3 was more similar to that of a known compound 18 with a type d configuration [17] than dipiperamide B with a type c configuration [18]. Finally, 19 was concluded to contain the cyclobutane ring with a head-to-head structure, i.e., type d, based on the coupling constant of H-2 (H-2'') and H-3 (H-3'') (J 2,3 = 6.3 Hz, J 2,3'' = −0.8 Hz, J 2,2'' = 11.3 Hz, and J 3,3'' = 10.5 Hz) obtained by a simulation (Figure 5) [33,34]. Since 17, 18, and 19 are optically inactive, an enzymatic cyclization may not be involved in their biosynthesis.…”

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confidence: 99%

Alkamides from Piper nigrum L. and Their Inhibitory Activity against Human Liver Microsomal Cytochrome P450 2D6 (CYP2D6)

Subehan

Usia

Kadota

et al. 2006

Natural Product Communications

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Drug−herb interaction through inhibition of cytochrome P450 alters the pharmacological response and/or toxicities of drug used concomitantly. In our screening, Piper nigrum L. was observed to inhibit cytochrome P450 2D6 (CYP2D6) in human liver microsomes. Thus, the MeOH extract of this plant was investigated for their chemical constituents and 19 alkamides including a new pipercyclobutanamide were isolated. Their structures were elucidated on the basis of spectroscopic analyses. The isolated compounds were tested for their inhibition on human liver microsomal dextromethorphan O-demethylation activity, a selective marker for CYP2D6, and pipercyclobutanamide A (17) showed the most potent inhibition with an IC 50 value of 0.34 µM. The result demonstrated the potential of drug−alkamides interaction on concomitant consume of white pepper with the drugs being metabolized by CYP2D6.

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“…3), depending on the concentration of the solutions or in the crystalline state was reported earlier. [17][18][19] Steric conditions for the formation of the photodimers mentioned above are essentially different for chiral dopants 1 and 3 because of distinctions mainly in the position of the methyl group with respect to the C=C photoactive bond.…”

Section: Resultsmentioning

confidence: 99%

Liquid‐crystal chiral‐nematic systems with photoinduced helix inversion

et al. 2004

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Abstract— The induced helical pitch in liquid‐crystalline systems based on 4‐pentyl‐4′‐cyanobiphenyl (5CB) and containing chiral 6‐arylidene derivatives of 3(R)‐methylcyclohexanone has been found to change its sign and to decrease in the absolute value when exposed to the UV irradiation. After the photostationary state is reached, the pitch remains invariable regardless of any consequent light radiation. This state is characterized by a large helical twist which exceeds an initial one in more than three times, thereby making it possible to obtain compositions with the selective reflection of light in the visible spectral region. This phenomenon could be utilized in colour filters for display devices. The effect observed is caused by the effective reversible photochemical E‐Z‐isomerization of the chiral dopant. This was proved by photochemical preparative synthesis of one of the respective Z‐isomers and independent studies of its behaviour in 5CB.

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Photocycloaddition of chalcones to yield cyclobutyl ditopic cyclophanes

Cited by 20 publications

References 23 publications

Photochemical transformations of chalcone-podands into cyclobutane-containing benzocrown ethers

Photochemical transformations of chalcone-podands into cyclobutane-containing benzocrown ethers

Alkamides from Piper nigrum L. and Their Inhibitory Activity against Human Liver Microsomal Cytochrome P450 2D6 (CYP2D6)

Liquid‐crystal chiral‐nematic systems with photoinduced helix inversion

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