Cycloadditions with StereoselectiveCNBond Formation in Total Syntheses

Abstract

Cycloadditions reactions are very efficient tools for the constructions of multiple bonds in one step and are therefore methods of choice for the total synthesis of natural products and drugs. The use of a terminal nitrogen containing partner allows for the stereoselective formations of a CN bond. Because of the vast number of nitrogen containing compounds available, this field has found a widespread interest in total synthesis. This chapter will cover the cycloadditions in which a CN bond is formed. It will be devoted to the description of [2+2], [3+2], [3+3], [4+2], and [2+2+2] processes that are key steps in total synthesis with imine, nitroso, azo, isocyanate, azomethine imine, azide, or azadiene reagents. A discussion of regioselectivity, diastereoselectivity, and enantioselectivity issues will be provided for each reaction.

Access to highly substituted oxazoles by the reaction of α-azidochalcone with potassium thiocyanate

“…In this work, it is shown that highly substituted oxazoles and aminothiazoles could be accessed directly from the reaction of substituted α-azidochalcones with potassium thiocyanate. Thiocyanate is a known ambident reagent with two potential sites of attack, enabling the selective and efficient construction of C-C and C-N bonds towards biologically important heterocyclic skeletons [62][63][64].…”