Carbon-nitrogen-sulfur-oxygen rings

CARBON-NITROGEN-OXYGEN/SULFUR-METAL RINGS... [Pg.387]

CARBON-NITROGEN-(OXYGEN and/or SULFUR)]" (n > 1) RINGS (CATENANES)... [Pg.384]

As reagents causing intramolecular recyclizations of 2-benzopyrylium salts, nucleophiles centered at nitrogen, oxygen, sulfur, or carbon atoms were used. As a fairly general rule, the ring opening of the heterocyclic moiety leads to an orf/io-quinonoid structure, as shown in more detail in Section III,C,4,iv (Structure 201). [Pg.190]

Cyclic organic compounds are classified as carbocycles or as heterocycles. CarbocycJic rings contain only carbon atoms, but heterocyclic rings contain one or more different atoms in addition to carbon. Nitrogen, oxygen, and sulfur are the most common heteroatoms. [Pg.1150]

Substances that contain one or more atoms other than carbon as part of a nng are called heterocyclic compounds Rings m which the heteroatom IS oxygen nitrogen or sulfur rank as both the most common and the most important... [Pg.136]

The alkylation desctibed in this article is the substitution of a hydrogen atom bonded to the carbon atom of a paraffin or aromatic ring by an alkyl group. The alkylations of nitrogen, oxygen, and sulfur are described in separate articles (see Amines Ethers). [Pg.45]

Big Chemical Encyclopedia