Transition‐Metal‐Free Deaminative Vinylation of Alkylamines

Abstract

The amino group is one of the most fundamental structural motifs in natural products and synthetic chemicals. However, amines potential as effective alkylating agents in organic synthesis is still problematic. A unified strategy has been established for deaminative vinylation of the alkylamines with vinyl boronic acids by CÀ N bond activation under catalyst-free conditions. The key to the high reactivity is the utilization of pyridinium salt-activated alkylamines, with a base as a promoter. The transformation exhibits good functional group compatibility, and includes inexpensive primary amine feedstocks and amino acids. The proposed method can serve as a powerful synthetic method for late-stage modification of complex compounds. Mechanistic experiments suggest that free radical processes are involved in this system.

Pyridinium Salts as Redox‐Active Functional Group Transfer Reagents

“…In principle,t he concept of PET could be applicable to adiverse array of substrates which form EDAcomplexes with pyridinium salts.A ne xample of this is the recently reported alkylation of indoles using amino acid derived pyridinium salts in the presence of an amine base, [55] as well as the use of 1 in the ipso-alkylation of vinylboronic acids. [56]…”

Recent Developments in Deaminative Functionalization of Alkyl Amines

“…In 2019, Loh and co‐workers reported a base‐promoted cross‐coupling reaction of the pyridinium salts and vinyl boronic acids (Scheme 23). [36] Reaction of ( E )‐styrylboronic acids with Katritzky salts in the presence of 1,8‐Diazabicyclo[5,4,0]undec‐7‐ene (DBU) in DMA at 80 °C afforded the ( E )‐vinylation products in good yields. Cyclic and acyclic secondary amines worked well in the reaction.…”

Pyridiniumsalze als redoxaktive Reagenzien zur Übertragung funktioneller Gruppen

“…Im Grunde könnte das PET‐Konzept auf eine Vielzahl von Substraten anwendbar sein, die EDA‐Komplexe mit Pyridiniumsalzen bilden. Beispiele dafür sind die kürzlich veröffentlichte Alkylierung von Indolen mit auf Aminosäuren basierenden Pyridiniumsalzen in Gegenwart einer Aminbase sowie die Verwendung von 1 bei der ipso ‐Alkylierung von Vinylboronsäuren …”