NMR Studies of Drugs. Applications of Achiral and Chiral Lanthanide Shift Reagents to the Analgesic, Famprofazone: “Anomalous Shifts”

Williams, Patricia Sakon; Troendle, Frederick J.; Venkatasubban, K. S.; Rothchild, Robert

doi:10.1080/00387019608007118

Cited by 6 publications

(1 citation statement)

References 19 publications

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“…Rotations about bonds to aromatic rings, especially C-aryl and N-aryl rotations, have been particularly significant for numerous drug systems. Some examples include the C-aryl rotation in the benzodiazepine, ketazolam [9] and the N-aryl rotations in the potential antipsoriatic, Sch40120, [10] the muscle relaxant, afloqualone, [11] famprofazone (an analog of amphetamine) [12] and antipyrine. [13,14] N-Aryl rotations have also been important in the strictly controlled (Schedule I of the Controlled Substances Act) sedative-hypnotics, methaqualone, [15] and mecloqualone.…”

Section: Nmr Studies Of Crowdedmentioning

confidence: 99%

NMR Studies of Crowded Diels–Alder Adducts of 3,6‐Dibromophencyclone withN‐(2,6‐Dialkylphenyl)maleimides. Hindered Rotations and Magnetic Anisotropy. Ab Initio Calculations for Optimized Structures of the Precursor Maleimides and Their Adducts with Phencyclone and 3,6‐Dibromophencyclone

Tokhunts¹,

Ramirez²,

Rothchild³

2004

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6,9-Dibromo-1,3-diphenyl-2H-cyclopenta[l]phenanthren-2-one (commonly known as 3,6-dibromophencyclone), 1b, reacted with N-(2,6-dimethylphenyl)maleimide, 2a; with N-(2,6-diethylphenyl)maleimide, 2b; and with N-(2,6-diisopropylphenyl)maleimide, 2c, respectively, to yield the corresponding Diels -Alder adducts, 4a -c. The adducts were extensively characterized by NMR (7 T) at ambient temperatures using one-and twodimensional (1D and 2D) proton and carbon-13 techniques for assignments. Slow exchange limit (SEL) spectra were observed, demonstrating slow rotations on the NMR timescales, for the unsubstituted bridgehead phenyl groups [C(sp 3 )-C(aryl sp 2 ) bond rotations] and for the 2,6-dialkylphenyl groups [N(sp 2 ) -C(aryl sp 2 ) bond rotations]. Substantial magnetic anisotropic shifts were seen in the adducts. For example, in the N-(2,6-dialkylphenyl) moieties of the adducts, one of the alkyl groups is directed "into" the adduct cavity, toward the phenanthrenoid portion, and these "inner" alkyl proton NMR signals were shifted upfield. Thus, in CDCl 3 , the inner methyl of adduct 4a exhibits a proton resonance at 20.05 ppm, upfield of tetramethylsilane (TMS); the inner ethyl group signals from 4b appear at 0.09 ppm (CH 2 , quartet) and 20.11 ppm (CH 3 , triplet); and the inner isopropyl group from 4c is seen at 20.10 ppm (methine, approx. septet) and, 20.28 ppm (CH 3 , doublet). Ab initio molecular modeling results are presented for the precursor maleimides, 2, and their adducts, 3, from the parent phencyclone, 1a, at the restricted Hartree-Fock level using the 6-31G Ã basis set. Results for the dibromoadducts, 4, used the LAV3P Ã basis set.

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Section: Nmr Studies Of Crowdedmentioning

confidence: 99%

NMR Studies of Crowded Diels–Alder Adducts of 3,6‐Dibromophencyclone withN‐(2,6‐Dialkylphenyl)maleimides. Hindered Rotations and Magnetic Anisotropy. Ab Initio Calculations for Optimized Structures of the Precursor Maleimides and Their Adducts with Phencyclone and 3,6‐Dibromophencyclone

Tokhunts¹,

Ramirez²,

Rothchild³

2004

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NMR Studies of Drugs: Antipyrine and Analogs. I. Use of Achiral and Chiral Lanthanide Shift Reagents to Examine Hindered Rotation.

Elias

Roberts

Venkatasubban

et al. 1997

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NMR Studies of Drugs: Antipyrine and Analogs. II.¹H and¹³C Chemical Shift Dispersion as Conformation Indicator for theN-Phenyl Ring.

Venkatasubban

Rothchild

1997

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NMR Studies of Drugs. Applications of Achiral and Chiral Lanthanide Shift Reagents to the Analgesic, Famprofazone: “Anomalous Shifts”

Cited by 6 publications

References 19 publications

NMR Studies of Crowded Diels–Alder Adducts of 3,6‐Dibromophencyclone withN‐(2,6‐Dialkylphenyl)maleimides. Hindered Rotations and Magnetic Anisotropy. Ab Initio Calculations for Optimized Structures of the Precursor Maleimides and Their Adducts with Phencyclone and 3,6‐Dibromophencyclone

NMR Studies of Crowded Diels–Alder Adducts of 3,6‐Dibromophencyclone withN‐(2,6‐Dialkylphenyl)maleimides. Hindered Rotations and Magnetic Anisotropy. Ab Initio Calculations for Optimized Structures of the Precursor Maleimides and Their Adducts with Phencyclone and 3,6‐Dibromophencyclone

NMR Studies of Drugs: Antipyrine and Analogs. I. Use of Achiral and Chiral Lanthanide Shift Reagents to Examine Hindered Rotation.

NMR Studies of Drugs: Antipyrine and Analogs. II.¹H and¹³C Chemical Shift Dispersion as Conformation Indicator for theN-Phenyl Ring.

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NMR Studies of Drugs. Applications of Achiral and Chiral Lanthanide Shift Reagents to the Analgesic, Famprofazone: “Anomalous Shifts”

Cited by 6 publications

References 19 publications

NMR Studies of Crowded Diels–Alder Adducts of 3,6‐Dibromophencyclone withN‐(2,6‐Dialkylphenyl)maleimides. Hindered Rotations and Magnetic Anisotropy. Ab Initio Calculations for Optimized Structures of the Precursor Maleimides and Their Adducts with Phencyclone and 3,6‐Dibromophencyclone

NMR Studies of Crowded Diels–Alder Adducts of 3,6‐Dibromophencyclone withN‐(2,6‐Dialkylphenyl)maleimides. Hindered Rotations and Magnetic Anisotropy. Ab Initio Calculations for Optimized Structures of the Precursor Maleimides and Their Adducts with Phencyclone and 3,6‐Dibromophencyclone

NMR Studies of Drugs: Antipyrine and Analogs. I. Use of Achiral and Chiral Lanthanide Shift Reagents to Examine Hindered Rotation.

NMR Studies of Drugs: Antipyrine and Analogs. II.1H and13C Chemical Shift Dispersion as Conformation Indicator for theN-Phenyl Ring.

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NMR Studies of Drugs: Antipyrine and Analogs. II.¹H and¹³C Chemical Shift Dispersion as Conformation Indicator for theN-Phenyl Ring.