Sequential stereodivergent organocatalysis and programmed organocascades

Abstract

Asymmetric organocatalysis has attracted great interest as a synthetic strategy during the past decade. But, although the inertness of organocatalysts to moisture and oxygen offers great opportunities to tune the reaction conditions, the stereoswitchable character of organocatalysts has not been systematically studied, and most findings have been serendipitous. In this Perspective, we emphasize the importance of in situ tunability in dynamic asymmetric organocatalysis for obtaining different functional outcomes with single-flask operation.

Real‐Time Control of the Enantioselectivity of a Supramolecular Catalyst Allows Selecting the Configuration of Consecutively Formed Stereogenic Centers

“…In fact, both enantiomers of a product can be obtained from the same catalyst in a predictable manner by connecting a catalytic unit to a chiroptical switch . However, the switch is commonly performed before the catalytic experiment . Controlling the enantiomeric state of a single catalyst in situ faces additional challenges: i) the catalytic system should be dynamic in the conditions of the catalytic reaction, ii) the stereochemical switch should be fast and lead to opposite chiral environments and, iii) the input should preserve the integrity of the catalyst.…”

Catalytic Strategies for Diastereodivergent Synthesis

“…On the other hand, when the commercially available chiral phosphoric acid ( S )‐ 56 was added as additive in acetone at 40 °C, the strong hydrogen‐bonding ability of the phosphate counteranion and the reaction medium switched the structural assembly of the iminium intermediate, and induced an anti ‐diastereoselective pathway (Scheme ) . What's more, the switching diastereoselection can be operated during the course of the reaction and in a single reaction flask (Scheme ) …”

Stereodivergent Catalysis

“…Although important stereodivergent developments have been achieved, still there are not well-defined strategies, serendipity being the most important factor on these findings. However, this topic has been only partially covered. − The aim of this review is to overview, for the first time, this efficiency concept in synthetic organic chemistry to get some light about which reactions are good candidates for stereodivergent catalytic transformations. Although, asymmetric catalytic reactions have been mainly presented, some asymmetric processes using chiral substrates and achiral catalysts are also considered.…”