Recent advances in synthetic methodologies for transition metal-free Ullmann condensation reactions

The enormous utility and significance of carbon-heteroatom compounds has stimulated the development of various transformations for coupling reactions. Although substantial improvements have been made in this field, formation of carbon-heteroatom bonds still remains a challenge to synthetic chemists, owing to employment of costly metal catalysts, toxic solvents and stringent reaction conditions. Therefore, it is important to design alternative milder protocols for transition metal-free coupling reactions. Herein, we provide a concise view of recent advances in various transition metal-free methodologies for carbon-heteroatom bond formation. This review will hopefully fulfil the expectations of readers who are interested in advancements made in this field and are looking for an update.