Asymmetric cycloaddition reactions catalysed by diarylprolinol silyl ethers

Abstract

Cycloaddition reactions are among the most important tools for the construction of cyclic compounds in organic synthesis, since these reactions are vital to access natural products and biologically active compounds. Organocatalysis plays an increasingly pivotal role in these reactions, often allowing several stereocenters to be selectively created and integrated in the target molecule. Among the large number of efficient types of organocatalysts available, the diarylprolinol silyl ethers have been established as one of the most frequently used in aminocatalysis allowing for novel activation modes and reaction concepts. In this review, we will focus on the different activation modes made available by the diarylprolinol silyl ether system with the aim of highlighting their applicability in asymmetric cycloadditions for the assembly of complex molecular architectures.

Diaryl Prolinols in Stereoselective Catalysis and Synthesis: An Update

“…Among the organocatalytic processes, [4+2] cycloaddition reactions received particular attention to obtain six‐membered carbo‐ and heterocycles with high regio‐ and stereocontrol . In this context, chiral non racemic pyrazolone‐based derivatives occupy an important place, being frequently found units in natural products and drugs .…”

“…Among the organocatalytic processes, [4 + 2] cycloaddition reactions received particular attention to obtain six-membered carbo-and heterocycles with high regio-and stereocontrol. [32] In this context, chiral non racemic pyrazolone-based derivatives occupy an important place, being frequently found units in natural products and drugs. [33] A straightforward approach to produce optically active pyrazolone containing derivatives relies on aminocatalytic [4 + 2] cycloaddition reaction via dienamine intermediates in inverse-electron demand hetero-DielsÀ Alder (IEDHDA) reactions, combined with Michael acceptors.…”

The Game of Electrons: Organocatalytic Higher‐Order Cycloadditions Involving Fulvene‐ and Tropone‐Derived Systems

“…Cycloadditions can be defined as processes that enablethe annulationo fanew ring systems starting from acyclic precursors. [1][2][3] According to Huisgen's definition "the concept of cycloaddition gives af ormal description of an overall reaction but not am echanistic interpretation". [4] Therefore, such reactions can proceede ither throughc oncerted, concerted asynchronous, or step-wise mechanisms, and all these reactions belong to this very specious group of transformations.…”

α,β‐Unsaturated Amides as Dipolarophiles: Catalytic Asymmetric exo‐Selective 1,3‐Dipolar Cycloaddition with Nitrones

“…Given the inherent nature of cycloaddition reactions to forge two bonds in one event, they are extensively utilized to construct molecular architectures of interest . The 1,3‐dipolar cycloaddition (1,3‐DC) reaction is a cycloaddition reaction variant that couples 1,3‐dipoles and dipolarophiles to produce 5‐membered ring systems . Nitrones are an archetypal 1,3‐dipole commonly used in 1,3‐DC reactions with dipolarophiles having multiple bonds, allowing for expeditious access of multi‐substituted isoxazolidines.…”