Deformative transition of the Menschutkin reaction and helical atropisomers in a congested polyheterocyclic system

Synthesis and stability of 1-aminoalkylphosphonic acid quaternary ammonium salts

An effective protocol for the quaternization of simple 1-aminoalkylphosphonic acids under basic conditions using Me2SO4 as a convenient alkylating agent is reported. During the course of the reaction, phosphonic acid quaternary ammonium derivatives, along with their corresponding monoesters are formed. Subsequent direct acidic hydrolysis of the crude reaction mixture leads to the desired novel N,N,N-trialkyl-N-(1-phosphonoalkyl)ammonium salts with overall yields of up to 88%. The developed protocol is general in scope and the products are purified by simple crystallization to give stable solids. Novel quaternary ammonium salts bearing a phosphonic group are generally unreactive in acidic and alkaline media. However, some of them undergo Hofmann elimination and substitution reactions in the presence of a base.

Zinc-catalyzed C-H alkenylation of quinoline N-oxides with ynones: a new strategy towards quinoline-enol scaffolds

A zinc-catalyzed C-H alkenylation of quinoline N-oxides with ynones has been developed to rapidly assemble a broad collection of valuable quinoline-enol organic architectures. Uncommonly, this novel reaction involves C-H functionalization, and N-O, C-C and C[triple bond, length as m-dash]C bond cleavage in one operation, and leads exclusively to the formation of an enol rather than a keto product. Application of the enols generated was highlighted by further derivative transformation and preparation of a series of "BODIPY" analogues with high quantum yields (up to 86%).