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 [4-5].
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.