An unprecedented gold-catalyzed synthetic method for the direct assembly of aryl-annulated carbazoles from 2-alkynyl arylazides and alkynes is described. The reaction is proposed to proceed via a ...sequential cyclopropenation and intramolecular metal carbene/arene Friedel–Crafts-type reaction, respectively, mediated by two gold carbene intermediates.
A highly enantioselective three-component cascade reaction, consisting of an enantioselective 4+2 cycloaddition reaction catalyzed by chiral phosphoric acid and a subsequent catalytic intramolecular ...hydroamination by gold(I) complex, provides a unique method to access structurally diverse julolidine derivatives in high optical purity.
Organocatalytic enantioselective Biginelli and Biginelli-like reactions by chiral phosphoric acids derived from 3,3′-disubstituted binaphthols have been investigated. The size of 3,3′-substituents of ...the catalysts is able to control the stereochemistry of the Biginelli reaction. By tuning the 3,3′-disubstituents of the phosphoric acids, the stereochemistry of the Biginelli reaction can be reversed. This organocatalytic Biginelli reaction by Brønsted acids 12b and 13 is applicable to a wide range of aldehydes and various β-keto esters, providing a highly enantioselective method to access DHPMs. 3,3′-Di(triphenylsilyl) binaphthol-derived phosphoric acid afforded Biginelli-like reactions of a broad scope of aldehydes and enolizable ketones with benzylthiourea, giving structurally diverse dihydropyrimidinethiones with excellent optical purity. Theoretical calculations with the ONIOM method on the transition states of the stereogenic center forming step showed that the imine and enol were simultaneously activated by the bifunctional chiral phosphoric acid through formation of hydrogen bonds. The effect of the 3,3′-substituents in phosphoric acids on the stereochemistry of the Biginelli reaction was also theoretically rationalized. The current protocol has been applied to the synthesis of some pharmaceutically interesting compounds and intermediates, such as chiral thioureas, dihydropyrimidines, guanidines, and the precursor of (S)-l-771688.
Since its advent two decades ago, asymmetric organo/transition-metal combined catalysis (AOMC), including cooperative catalysis and relay catalysis, has leveraged redistribution of chemical bonds to ...build up molecular complexity and enantio-differentiation to form individual enantiomers with activations from versatile organocatalysts and transition-metal complexes. The goal of this perspective is to provide readers with the fundamental attributes of AOMCorthogonality, kinetics, mechanism, and selectivityto understand how an organocatalyst and a transition-metal complex would collaborate to enable fruitful new reaction development and what are the intrinsic pathways of unproductive events, such as catalyst self-quenching. In closing, future opportunities of AOMC have been directed toward the prediction of effective catalyst combination, introducing enzyme catalysis, and a focus on transient radical intermediate, to animate this area in the years to come.
The first highly stereoselective organocatalytic intermolecular allylic alkylation of allylic alcohols with 1,3-dicarbonyls has been developed to allow the first enantioselective total synthesis of ...hydroxymetasequirin-A and metasequirin-B tetramethyl ether diacetates.
A highly regio- and enantioselective allylic C-H alkylation of 1,4-dienes with glycine Schiff bases has been established by chiral palladium-phosphoramidite catalysis. This reaction can proceed under ...mild conditions and tolerate a wide scope of 1,4-dienes, delivering structurally diverse chiral β-branched a-amino acid surrogates in moderate to high yields and with high levels of regio-,
Z
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-, diastereo- and enantioselectivities.
An enantioselective organocatalytic addition of nitroalkanes to oxindolylideneindolenines in the presence of bifunctional organocatalysts has been established to provide an efficient entry to ...3,3‐disubstituted oxindole derivatives in high yields and with excellent enantioselectivities. The transformation has been applied to the preparation of the key intermediate for a formal total synthesis of (+)‐gliocladin C.
The kinetic resolution of racemic 2,3-allenoates was realized via 1,3-dipolar cycloaddition by using a bisphosphoric acid catalyst, affording the optically active 2,3-allenoates and ...3-methylenepyrrolidine derivatives in high yields and enantioselectivities.
The Biginelli reaction, known for over 100 years, is an important multicomponent reaction for accessing dihydropyrimidinones (DHPMs). The individual enantiomers of DHPMs exhibit different or even ...opposite pharmaceutical activities, which require synthetic methods to easily access the optically pure DHPMs. In recent decades, many efforts have focused on developing procedures for the preparation of optically active Biginelli products. In this article, we will summarize the developments in the synthetic methods to access optically active DHPMs with an emphasis on the recent advances in the asymmetric catalytic Biginelli reactions, along with concepts to design the organocatalytic asymmetric variants.
Optically active compounds, that is, 3,4‐dihydropyrimin‐2‐(1H)‐ones, can be obtained in the catalytic asymmetric Biginelli reaction with chiral Brønsted acids (see scheme). Various reaction conditions and catalysts are also discussed.
Silver‐standard selectivity! The first highly enantioselective formal 3+2 cycloaddition reaction of isocyanoesters with 2‐oxobutenoate esters catalyzed by a chiral silver complex proceeded readily ...under the catalysis of a multifunctional chiral silver complex in high yields and enantiometric excess (ee) values of up to 98 % (see scheme).
