Virtual Lecture: Exploiting the Versatile N-O Bond: Synthesis of Amines and N-heterocycles

Lecture held on: June 29, 2022

Presenter

Prof. László Kürti – Department of Chemistry, Rice University, Houston, TX, USA

Synthesis of highly substituted and strained nitrogenous molecules remains a challenging task since installing substituents on small ring systems gets increasingly difficult as the degree of substitution increases. Similarly, it is difficult to install nitrogen bridges onto highly substituted and electronically diverse unsaturated systems. In this lecture, Prof. László Kürti presented a number of synthetic routes to these valuable nitrogenous building blocks. The direct and stereospecific synthesis of N-H and N-alkyl aziridines from unactivated olefins using both transition metal catalyzed and organocatalytic
approaches that proceed through very different N-transfer processes. Fully substituted N-acyl aziridines were produced in one pot by the reaction of N electrophilic iminomalonates with ketone enolates this transformation is in essence an aza quasi Favorskii rearrangement reaction which proceeds via a 1,2-attack followed by a low barrier intramolecular nitrenoid insertion into a C-C bond and structurally diverse spiro N-H azetidines were formed in a single step during the Ti(IV)-mediated reaction between oxime ethers and alkyl-Grignard reagents or via a ligand exchange process using
terminal olefins the overall transformation proceeds via a Kulinkovich type mechanism a titanacyclopropane intermediate is formed and serves as a 1,2-dialkyl anion equivalent, inserting into the 1,2-dielectrophilc oxime ether to ultimately give rise to the desired N-heterocyclic four membered ring.