1,2-Azaphosphinane and 1,2-azaphosphinine 2oxides, δ-phosphonolactams and δ-phosphinolactams, are important six-membered azaphosphaheterocycles and crucial scaffolds of some biological and organic material compounds. Dibenzo[c,e][1,2]azaphosphinine 2-oxides are both chiral ligands and precursors of chiral atropisomeric P,N-biaryl ligands. Various synthetic methods of these azaphosphaheterocycles have been developed till now. They can be classified as cyclization, including cyclization of haloalkyl-phosphonamidates and phosphinamides, condensation of aminoalkylphosphonic/phosphinic acids, ring closing metathesis of N-allylallylphosphinamides, the palladium-catalyzed cyclizations of 2-alk-1-ynylarylphosphonamidates and N-(2bromoaryl)diarylphosphinamides, oxidative cyclization of 2arylarylphosphinamides, annulation, and cycloaddition. In this Focus Review, we have described various strategies for the synthesis of 1,2-azaphosphinane and 1,2-azaphosphinine 2-oxides. Scheme 1. Synthesis of 1-aryl-2-arylamino-1,2-azaphosphinane 2-oxides via nucleophilic cyclization of N,N'-diaryl-4-chlorobutylphosphonodiamides under basic conditions. Scheme 2. Synthesis of 1,2-azaphosphinane 2-oxides via nucleophilic cyclization of ethyl 4-bromobutylphosphonamidate and 4-bromo-P-phenylbutylphosphinamide under basic conditions. Scheme 3. Synthesis of 2-ethoxy-6-oxo-1,2-azaphosphinane 2-oxides via intramolecular aminolysis of 4-(P-amino-P-ethoxyphosphinyl)butanoates. Scheme 4. Synthesis of bicyclic 1,2-azaphosphinane 2-oxides via cyclization of zwitterionic 5-amino-3-phosphorylmethyl-D-ribufuranoses with watersoluble coupling reagent EDC . HCl. Scheme 5. Synthesis of 2-ethoxy-1,3,4-trihydrobenzo[e][1,2]azaphosphinine 2-oxide via cyclocondensation of ethyl 2-(2-aminophenyl)ethylphosphonic monoester.