The ring expansion of saturated heterocycles through methylene insertion into N–O
bonds using a zinc carbenoid is described. This transformation is applied to 1,2-oxazetidines
and 1,2-oxazolidines, while N-tosylated 1,2-oxazinane affords a ring-opened product. Density functional theory
calculations suggest a stepwise reaction mechanism of the ring expansion and elucidate
the origins of the different reactivities observed.
Key words
saturated heterocycles - ring expansion - zinc carbenoid - insertion - DFT calculations
