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This survey describes how the chemistry of lithiated oxygen heterocycles has been fruitfully exploited, particularly over the last 10 years, for the preparation of more (stereodefined) functionalized derivatives and products derived from them. Also, how they have contributed to natural product synthesis and molecules of relevant pharmaceutical interest. The genesis of the reactive lithiated intermediates (especially α- and ortho -lithiated (hetero)arylepoxides, -oxetanes and -tetrahydrofurans) requires a careful choice of the experimental conditions in terms of solvents and temperature in order them to be successfully intercepted by electrophiles. The study of the aggregation and solvation of certain chiral functionalized lithiated oxygen heterocycles has provided further hints about the factors affecting their configurational stability and their carbanionic/carbene-like character, and the way the latter can be finely tuned to facilitate the desired reactivity for synthetic purposes.

The chemistry of four-membered heterocycles including one oxygen and one nitrogen atom, which was previously reviewed in 1984 and 1996, has been now updated. Special attention has been paid to the spectroscopic part, in particular, to proton and carbon-13 data of many 1,2-oxazetidine derivatives (which have been collected and listed in three tables); methods allowing the assignment of the relative and absolute configuration of such heterocyclic systems, based on the calculation of vicinal homocoupling, long-range heterocoupling constants and nuclear Overhauser effect (NOE) correlations, have been discussed as well. Starting from 1996, the main ring syntheses reported in the literature in the case of 1,2-oxazetidines, which are the most representative class of these derivatives, refer to a ring closure of a single component as well as to transformations of another ring. Thermodynamic aspects, ring-chain isomerism, reactivity of unsaturated and nonconjugated rings and that of substituents attached to ring atoms have also been reviewed.