Fluorocyclization of Allyl Alcohols and Amines to Access 3-Functionalized Oxetanes and Azetidines
An efficient method to prepare 3-functionalized oxetanes and azetidines has been realized by fluorocyclization of readily available 2-azidoallyl/2-alkoxyallyl alcohols and amines. Notably, this is the first example applying the fluorocyclization strategy to construct four-membered heterocycles. The pendant electron-donating group (-N3 or -OR) plays a crucial role in polarizing the C= C double bond and facilitating the cyclization process, as verified by DFT and experimental studies.
Silver(I)-catalyzed hydroazidation of ethynyl carbinols: Synthesis of 2-azidoallyl alcohols
The hydroazidation of alkynes is the most straightforward pathway to synthetically useful vinyl azides. However, a general hydroazidation of alkynes remains elusive. Herein, a chemo- and regioselective transformation of ethynyl carbinols into vinyl azides is described. This reaction produces a wide variety of 2-azidoallyl alcohols with high efficiency and in good to excellent yields. These compounds constitute a new class of densely functionalized synthetic intermediates. Their synthetic potential has been demonstrated by further transformations into NH aziridines. The mechanistic aspects of the reaction will attract the attention of chemists working on alkyne chemistry and silver catalysis. The findings that are described in this paper represent significant advances in the regioselective hydroelementation of alkynes and open a new reaction manifold for exploitation. Azides and aziridines: The hydroazidation of unactivated alkynes by means of silver catalysis is described. A variety of ethynyl carbinols are capable of reacting with trimethylsilyl azide to produce 2-azidoallyl alcohols in good to excellent yields. The synthetic utility of 2-azidoallyl alcohols was demonstrated by further conversion into NH aziridines.