Desymmetrization Process by Mg(II)-Catalyzed Intramolecular Vinylogous Michael Reaction

Abstract

Chiral magnesium catalyzed intramolecular vinylogous Michael reaction of novel cyclohexadienones via a desymmetrization process is reported. (R)-BINOL derived ligand and an achiral amide were employed in the current in situ generated magnesium catalyst, giving the corresponding hydrogenated benzofuranone skeletons in good to excellent enantioselectivities with high yields. This simple and efficient strategy could be utilized for the synthesis of aromatized α,β-unsaturated ester and Br-substituted hydrogenated benzofuranone in good yields under mild conditions. Letter pubs.acs.org/OrgLett

Asymmetric magnesium catalysis for important chiral scaffold synthesis

“…41 On the basis of this piece of work, the utilization of the bifunctional Mg( ii ) catalyst was also successfully realized for the desymmetrization of the dienone substrate 14-6 (Scheme 14b). 42…”

“…41 On the basis of this piece of work, the utilization of the bifunctional Mg(II) catalyst was also successfully realized for the desymmetrization of the dienone substrate 14-6 (Scheme 14b). 42 The Diels-Alder reaction is a powerful cycloaddition strategy for building poly-substituted cyclohexenes that is widely applied in natural product total synthesis. 43 The cycloaddition between 2,4-hexadienol and methyl acrylate can efficiently build fused lactone structures that are highly valuable starting motifs.…”

Recent advances in intramolecular kinetic resolution reactions

“…In 2020, we successfully achieved a magnesium-catalyzed 32 vinylogous-Michael type intramolecular KR reaction, which can be used for the rapid synthesis of complex chiral parallel [6,6,5]-tricyclic skeletons. 33 The reaction showed wide applicability to different alkyl- and aryl-substituted substrates and afforded high enantioselectivities of tricyclic products (Scheme 22). Moreover, the resolution reaction could be carried out on a gram scale and the resulting chiral allyl ester substrate 45a was successfully transformed into the enantiomer adduct 46a′ by treating it with a simple base NaOMe.…”

DABCO‐Catalysed [3+2] Cyclization/Deformylation Cascade of p‐Quinols with 3‐Formylchromones: Access to Benzopyrone‐Fused Tetracyclic Ring Systems

“…[4] For instance, the extensive studies by Jefford, [5] Harned, [6] Carreño, [7] Rovis, [8] Johnson [9] and other groups [10] have disclosed that p-quinols could participate in various [3 + n] cyclization reactions with unsaturated double-bond containing compounds such as aldehydes, imines and cinnamaldehydes under organocatalysis or transition metal catalysis to build structurally and functionally diverse hydrobenzofuranones or other cyclohexanone-fused heterocyclic ring systems. In addition, extending this domino annulation/desymmetrization strategy to use p-quinol derivatives has also been proved to be powerful for the construction of hydrobenzofuranone skeletons, as selected examples from Tian & Lin, [11] Wang [12] and other groups [13] show. On the other hand, owing to their high electrophilicity, adequate stability and versatile reactivity, the 3-formylchromones are extensively used in various Michael addition or annulation reactions to afford a series of benzopyrone-containing heterocyclic ring systems.…”