Access to 3-Azetidines via Halogenation of Titanacyclobutanes.

Azetidines are valuable nitrogenous heterocycles. Herein, we disclose a strategy for the modular assembly of 3-azetidines and related spirocyclic congeners featuring all-carbon quaternary centers. This approach leverages titanacyclobutanes generated from ketones or alkenes. Halogenation of these organotitanium species gives rise to functionalized alkyl dihalides that can be subsequently captured by amines to afford azetidine building blocks. This strategy facilitated the synthesis of a small molecule anti-tuberculosis drug. It also enabled access to carbon-13 isotopologs of diazaspiro[3.3]heptane fragments that are challenging to prepare by any other means.