This results in the formation of a big, essential planar heterocyclic ring
system with 4.349[degrees] and 5.217[degrees] dihedral angle between the newly formed ether ring and the two original coumarin rings, respectively.
Polyphenols share a common structural component: a phenol or an aromatic ring, usually two, with at least one hydroxyl, methyl, or acetyl group linked via a three-carbon bond to form a six-unit heterocyclic ring
. (8,9) When the "parent polyphenol" known as cinnamic acid is further catalytically transformed, scores of polyphenolic compounds result.
This volume outlines a methodology of regioselective synthesis of aromatic and nonaromatic carbocyclic and heterocyclic ring
systems based mainly on [2+2+2] and [4+2] cycloaddition, and other reactions of acetylenic units, including enediynes and enyne-allenes.
The equilibrium is slow and, besides the aromatic signals of the phenyl groups, which are coincident, most of the other signals both from the purine heterocyclic ring
and the isoxazoline-cyclopentanol moiety differ remarkably allowing for the clear resolution of the two tautomers.
Some new derivatives of natural dipeptide antibiotics TAN 1057 A, B containing heterocyclic ring
and [beta] -amino acid as a side chain were synthesized and screened for the in vitro antimicrobial activity by Brands et al.
These observations are due to heterocyclic rings
of coumarin moiety, triazole heterocyclic ring
, and oxathiazolidinone heterocyclic ring
incorporated in the molecular structure of the metal complexes.
The amino group is ready-made nucleophilic center for the synthesis of condensed heterocyclic ring
Their synthesis, which appeared in the Journal of the American Chemical Society (2003, 125, 9308), employs a tandem Diels-Alder/allylboration strategy which installs both stereocentres and the heterocyclic ring
rapidly and with high levels of enantiomeric control.
This definition has been extended to include steroids with a heterocyclic ring
fused or attached to the steroid skeleton.
The presence of electron withdrawing substituent at benzimidazole phenyl ring and alkyl substitution at heterocyclic ring
play vital role in the urease inhibitory activity.