Phenyl group: defined

Complete removal of the 4-phenyl substituent of the reversed ester of pethidine results in a drastic fall in potency as judged from tests in mice (see 23, R = Et). However, certain esters of l-methyl-4-piperidinol formed from aromatic acids display antinociceptive activities in the morphine to codeine range of potency (23).<68) A QSAR study of such esters has been made and a substitution pattern of the phenyl group defined for optimal activity/69 The relevance of these compounds to morphine-type analgesics is doubtful since the more active members show marginal or no affinity for opioid receptors of rat brain homogenates and display no physical dependence in monkeys. 

In contrast to the unsubstituted ring compounds 118 and 120,1,1-diaryl-, 1,1-dialkyl- or l-aryl-l-alkyl-X -phosphorins with three phenyl groups in positions 2,4 and 6 of the X -phosphorin ring 122 are much easier to prepare and to handle. They can be obtained either from 2.4.6-triphenyl-pyrylium salts or from 2.4.6-triphenyl-X -phosphorins. Most of these 2.4.6-tri-substituted X -phosphorins are very stable and can be isolated as well-defined crystalline compounds. They do not react with the above-mentioned cations. However, reversible protonation-deprotonation does take place in the presence of acids. 

Conformational energies of meso and racemic diads of PS are computed as functions of skeletal bond rotations. Confinement of rotations of the phenyl groups to a small range within which they are nearly perpendicular to the plane defined by the two adjoining skeletal bonds is confirmed. Steric interactions involving the relatively large planar phenyl group virtually preclude"g" conformations. A simple, two-state RIS scheme is applicable with states at 170° and 70° for both meso and racemic dyads. 

By the use of a model reaction (ionization of benzoic acids), die ability of a substituent to modify die electron-donating or electron-withdrawing ability of die phenyl group and tiius influence tiiat reaction can be defined quantitatively by the Hammett equation,... 

The C=C olefin double bond is usually considered to be an electron-rich centre which is prone to reactions with electrophiles. When strong electron-releasing groups such as amino, alkoxy or phenyl groups are bonded to the carbon atoms forming the double bond, the jr bond s capacity to release electrons is enhanced and the olefin is defined as an electron-donor olefin. On the other hand, when the C=C double bond bears substituents that attract electrons, the olefin is an electron-acceptor olefin. 

The 3-benzyl-6-phenyl-l,4-diazepine-2,5-diones 21 and 22 exhibited complex NMR spectra indicative of limited conformational mobility in which the ring geometry is dictated by the two air-amide elements, which define individual planes <2003MI187>. Based on an analysis of the nuclear Overhauser effect (NOE) between protons on the ring, the preferred boat conformation in solution projects the 3-benzyl moiety pseudoequatorially with the 6-phenyl substituent disposed axially or equatorially, dependent upon the relative stereochemistry. This conformation is also observed in the solid state for the air-substituted isomer 21 in which the phenyl group is axial. In contrast, the bis-phenyl derivative 23 is conformationally mobile based on the H NMR spectmm where resonances were not resolved. 

If the reducible heterocyclic ring is considered as one polarographically active group, three types of reaction series can be defined (1) those in which the reducible heterocycle is substituted in a fixed position by different substituents (2) those where the reducible ring is substituted by the same substituent in different positions relative to the heteroatoms and (3) those in which the heterocyclic ring is substituted in a fixed position by a phenyl group with a substituent in the m- or -position with respect to the heterocyclic ring. 

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