anti

https://doi.org/10.1351/goldbook.A00381
In the representation of stereochemical relationships 'anti' means 'on opposite sides' of a reference plane, in contrast to '@S06216@' which means 'on the same side', as in the following examples.
  1. Two substituents attached to atoms joined by a single bond are anti if the @T06406@ (@D01730@) between the bonds to the substituents is greater than 90°, or @S06216@ if it is less than 90°. (A further distinction is made between @T06406@, @T06406@, @T06406@ and @T06406@.)
  2. In the older literature the terms anti and @S06216@ were used to designate @S05984@ of @O04372@ and related compounds. That usage was superseded by the terms '@C01092@' and 'cis' or E and Z, respectively.
  3. When the terms are used in the context of @C01033@ or @T06446@, they designate the relative orientation of substituents in the substrate or product:
    1. Addition to a carbon-carbon double bond:
      A00381-1.png
      A00381-2.png
    2. Alkene-forming @E02038@:
      A00381-3.png
      A00381-4.png
      In the examples described under (1) and (2) anti processes are always @A00377@, and @S06216@ processes are @A00377@.
      See also:
      endo, exo, syn, anti
Sources:
PAC, 1994, 66, 1077.(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1084 [Terms] [Paper]
PAC, 1996, 68, 2193.(Basic terminology of stereochemistry (IUPAC Recommendations 1996)) on page 2199 [Terms] [Paper]