Preferred Label : anti;
IUPAC definition : in the representation of stereochemical relationships anti means on opposite sides
of a reference plane, in contrast to syn which means on the same side, as in the following
examples. two substituents attached to atoms joined by a single bond are anti if the
torsion angle (dihedral angle) between the bonds to the substituents is greater than
90 , or syn if it is less than 90 . (a further distinction is made between antiperiplanar,
synperiplanar, anticlinal and synclinal.) in the older literature the terms anti and
syn were used to designate stereoisomers of oximes and related compounds. that usage
was superseded by the terms trans and cis or e and z, respectively. when the terms
are used in the context of chemical reactions or transformations, they designate the
relative orientation of substituents in the substrate or product:addition to a carbon-carbon
double bond: alkene-forming elimination: in the examples described under (1) and (2)
anti processes are always antarafacial, and syn processes are suprafacial.;
Origin ID : A00381;
Automatic exact mappings (from CISMeF team)
- See also
in the representation of stereochemical relationships anti means on opposite sides
of a reference plane, in contrast to syn which means on the same side, as in the following
examples. two substituents attached to atoms joined by a single bond are anti if the
torsion angle (dihedral angle) between the bonds to the substituents is greater than
90 , or syn if it is less than 90 . (a further distinction is made between antiperiplanar,
synperiplanar, anticlinal and synclinal.) in the older literature the terms anti and
syn were used to designate stereoisomers of oximes and related compounds. that usage
was superseded by the terms trans and cis or e and z, respectively. when the terms
are used in the context of chemical reactions or transformations, they designate the
relative orientation of substituents in the substrate or product:addition to a carbon-carbon
double bond: alkene-forming elimination: in the examples described under (1) and (2)
anti processes are always antarafacial, and syn processes are suprafacial.
