Palladium-Catalyzed [1,3]-O-to-N Rearrangement of Allylic ­Imidates

The rearrangement of allylic imidates is a powerful transformation for the synthesis of allylic amines. Whereas the [3,3]-rearrangement has long been established as the Overman rearrangement, the corresponding [1,3]-rearrangement is rare. Here, we report a novel strategy for the [1,3]-rearrangement of imidates based on the oxidative addition of a palladium(0) catalyst to an allylic imidate. Structurally distinct allylic amides could be synthesized under mild and base-free conditions.

Electrochemical Synthesis of Allylic Amines from Alkenes and Amines

Allylic amines are valuable synthetic targets en route to diverse biologically active amine products. Current allylic C–H amination strate-gies remain limited with respect to the viable N-substituents. Herein we disclose a new electrochemical process to prepare aliphatic allylic amines by coupling two abundant starting materials: secondary amines and unactivated alkenes. This oxidative transformation proceeds via electrochemical generation of an electrophilic adduct between thianthrene and the alkene substrates. Treatment of these adducts with aliphatic amine nucleophiles and base provides allylic amine products in high yield. This synthetic strategy is also amenable to functionali-zation of feedstock gaseous alkenes at 1 atmosphere. In the case of 1-butene, remarkable Z-selective crotylation is observed. This strategy, however, is not limited to the synthesis of simple building blocks; complex biologically active molecules are suitable as both alkene and amine coupling partners. Preliminary mechanistic studies implicate vinylthianthrenium salts as key reactive intermediates.

Allylic alcohols and amines by carbenoid eliminative cross-coupling using epoxides or aziridines

α-Lithiated terminal epoxides and N-(tert-butylsulfonyl)aziridines undergo eliminative cross-coupling with α-lithio ethers, to give convergent access to allylic alcohols and allylic amines, respectively. The process can be considered as proceeding by selective strain-relieving attack (ring-opening) of the lithiated three-membered heterocycle by the lithio ether and then selective β-elimination of lithium alkoxide.

Ni-catalyzed hydroaminoalkylation of alkynes with amines

Allylic amines are versatile building blocks in organic synthesis and exist in bioactive compounds, but their synthesis via hydroaminoalkylation of alkynes with amines has been a formidable challenge. Here, we report a late transition metal Ni-catalyzed hydroaminoalkylation of alkynes with N-sulfonyl amines, providing a series of allylic amines in up to 94% yield. Double ligands of N-heterocyclic carbene (IPr) and tricyclohexylphosphine (PCy3) effectively promote the reaction.