In organic chemistry, a 1,3-dipolar compound or 1,3-dipole is a dipolar compound with delocalized electrons and a separation of charge over three atoms, as follows: the dipole has at least one resonance structure with positive and negative charges having a 1,3 relationship which can generally be denoted as +a−b−c−, where a may be a carbon, oxygen or nitrogen, b may be nitrogen or oxygen, and c may be a carbon, oxygen or nitrogen.
They are reactants in 1,3-dipolar cycloadditions. Known 1,3-dipoles are:
Azides (RN3) Ozone (O3) Nitro compounds (RNO2) Diazo compounds (R2CN2) Some oxides Azoxide compounds (RN(O)NR) Carbonyl oxides (Criegee zwitterions) Nitrile oxides (RCN−O) Nitrous oxide (N2O) Nitrones (R2CN(R)O)
Some imines: Azomethine imine Nitrilimines (RCN−NR, analogous to nitrile oxide) Carbonyl imines Some ylides Azomethine ylide Nitrile ylide (RCNCR'2) Carbonyl ylide Thiosulfines (R2CSS)
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