Catalyzed Vinylogous Mukaiyama Aldol Reactions with Controlled Enantio‐ and Diastereoselectivities

Abstract

In control: A new catalytic vinylogous Mukaiyama aldol reaction provides products with high diastereo- and enantioselectivities (up to 99 % de and ee; see scheme). The relative and absolute stereochemistry of a representative product was rigorously assigned by NMR and CD spectroscopies (measured and calculated), X-ray diffraction, and quantum-chemical calculations.

C1‐Symmetric Aminosulfoximines in Copper‐Catalyzed Asymmetric Vinylogous Mukaiyama Aldol Reactions

“…[24] Determination of the relative and absolute configuration: Previously, the absolute configuration of 5 g stemming from catalyses with S-configured sulfoximine 4 aA was determined as (R,R). [11] This enantiomer resulted from a preferential attack of the nucleophile from the Si face on the Re face of the electrophile (Scheme 7, top). Assuming that the reaction took place in the same manner as above, namely from the same sides of the reactants, a product with (S,R) configuration was expected for 5 p (Scheme 7, bottom).…”

“…[9a, 10] In a recent communication we extended the catalytic system of aminosulfoximine (S)-4 aA and CuA C H T U N G T R E N N U N G (OTf) 2 to cyclic dienol silanes 2 and ketonic electrophiles 3 (Scheme 2). [11] The resulting g-butenolides 5 were obtained in excellent yields and top-level diastereoand enantioselectivities. Additionally, the relative and absolute configuration of a representative product was identified beyond doubt.…”

A Simple Tetraminocalix[4]arene as a Highly Efficient Catalyst under “On‐Water” Conditions through Hydrophobic Amplification of Weak Hydrogen Bonds

“…[b] Combined yield of isolated diastereoisomers after column chromatography. [c] Determined by 1 H NMR analysis of crude reaction mixture according to literature data; in parentheses: d.r. of the product after column chromatography.…”

“…The structure refinement revealed that the mounted crystal corresponded to the syn ‐ 7 i diastereoisomers (Figure ). The relative stereochemistry of derivative 7 i was assigned accordingly, whereas for derivatives 7 a – h , j – l , the syn / anti stereochemistry was assigned on the basis of the reported NMR spectral data …”

“…[b] Determined by 1 H NMR analysis. [c] Determined by 1 H NMR analysis according to literature data . [d] Deionized water.…”