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The Nazarov cyclization reaction is a convenient, widely used method for the synthesis of cyclopentenones. In this account, we reviewed our recent efforts on the chiral proton-transfer shuttle catalysts promoted enantioselective Nazarov cyclization. We have synthesized various chiral cyclopenta[ b ]indoles and chiral α,α′-disubstituted cyclopentenones by means of cooperative catalysis of a Lewis acid and a chiral spiro phosphoric acid. The mechanistic studies revealed that the chiral spiro phosphoric acid acts as a multifunctional catalyst: it co-catalyzes the cyclization of the dienone and enantioselectively catalyzes a proton-transfer reaction of the enol intermediate via a hydrogen--bonding network. 1 Introduction 2 Enantioselective Nazarov Cyclization of Indole Enones 3 Enantioselective Silicon-Directed Nazarov Cyclization 4 Conclusion [ABSTRACT FROM AUTHOR]

Herein we report the first method for highly enantioselective Brønsted acid catalyzed Heyns rearrangements. These reactions, catalyzed by a chiral spiro phosphoric acid, afforded synthetically valuable chiral α‐aryl‐α‐aminoketones which cannot be obtained by means of previously reported Heyns rearrangement methods. This method features low catalyst loadings, high yields and high enantioselectivities, making these reactions highly practical. We used the method to efficiently synthesize various chiral amines, including some biologically active molecules. We experimentally proved that these acid‐catalyzed Heyns rearrangements proceeded via a proton‐transfer process involving an enol intermediate and the stereocontrol was realized during the proton‐transfer step. [ABSTRACT FROM AUTHOR]

Herein, we report the development of a method for highly regio‐, stereo‐, and enantioselective B−H bond insertion reactions of α‐silylcarbenes generated from 1‐silylcyclopropenes in the presence of a chiral copper(I)/bisoxazoline catalyst for the construction of chiral γ,γ‐disubstituted allylic gem‐silylboranes, which cannot be prepared by any other known methods. This reaction is the first highly enantioselective carbene insertion reaction of α‐silylcarbenes ever to be reported. The method shows general applicability for various 3,3‐disubstituted silylcyclopropenes and exclusively affords E‐products. The novel chiral γ,γ‐disubstituted allylic gem‐silylborane products are versatile allylic bimetallic reagents with high stability and have great synthetic potential, especially for the construction of complex molecules with continuous chiral centers. [ABSTRACT FROM AUTHOR]

The first highly enantioselective intramolecular N−H bond insertion was realized by using copper catalysts modified with chiral spirobisoxazoline ligands, which provides a novel strategy for the synthesis of chiral 2-carboxytetrahydroquinolines. This reaction features fast reaction rate, high yield, high enantioselectivity, and mild reaction conditions. [ABSTRACT FROM AUTHOR]

An iron-catalyzed asymmetric intramolecular cyclopropanation was realized in high yields and excellent enantioselectivity (up to 97 % ee) by using the iron complexes of chiral spiro-bisoxazoline ligands as catalysts. The superiority of iron catalysts exhibited in this reaction demonstrated the potential abilities of this sustainable metal in asymmetric carbenoid transformation reactions. [ABSTRACT FROM AUTHOR]

A highly enantioselective NH insertion reaction of α-diazoketones was developed by using cooperative catalysis by dirhodium(II) carboxylates and chiral spiro phosphoric acids. The insertion reaction provides a new access route to diverse chiral α-aminoketones, which are versatile building blocks in organic synthesis, with fast reaction rates, good yields and high enantioselectivity under mild and neutral conditions. [ABSTRACT FROM AUTHOR]

A palladium-catalyzed asymmetric OH insertion reaction was developed. Palladium complexes with chiral spiro bisoxazoline ligands promoted the insertion of α-aryl-α-diazoacetates into the OH bond of phenols with high yield and excellent enantioselectivity under mild reaction conditions. This palladium-catalyzed asymmetric OH insertion reaction provided an efficient and highly enantioselective method for the preparation of synthetically useful optically active α-aryl-α-aryloxyacetates. [ABSTRACT FROM AUTHOR]

An efficient catalytic asymmetric hydrogenation of racemic α-arylcyclohexanones with an ethylene ketal group at the 5-position of the cyclohexane ring via dynamic kinetic resolution has been developed, giving chiral α-arylcyclohexanols with two contiguous stereocenters with up to 99% ee and >99:1 cis/ trans-selectivity. Using this highly efficient asymmetric hydrogenation reaction as a key step, (−)-α-lycorane was synthesized in 19.6% overall yield over 13 steps from commercially available starting material. [ABSTRACT FROM AUTHOR]

Efficient: A copper‐catalyzed enantioselective intramolecular insertion of carbenoids into phenolic OH bonds has been developed. This method can be used for the synthesis of the title compounds in high yields and excellent enantioselectivities under mild and neutral conditions (see scheme). NaBArF=sodium tetrakis[3,5‐bis(trifluoromethyl)phenyl]borate. [ABSTRACT FROM AUTHOR]

Abstract: A highly enantioselective rhodium-catalyzed hydrogenation of both (Z)- and (E)-β-arylenamides was developed by using monodentate chiral spiro phosphite and phosphine ligands, respectively. The hydrogenation reaction provides an efficient access to optically active β-arylisopropylamines, important building blocks for the synthesis of biologically active compounds. [Copyright &y& Elsevier]

Abstract: By using iridium catalyst based on chiral spiro phosphine–oxazoline ligands, the hydrogenation of α-arylcinnamic acids was accomplished under ambient pressure and low catalyst loading (as low as 0.01 mol %), providing useful 2,3-diarylpropionic acids in high yields with excellent enantioselectivities (up to 99% ee). A catalytic enantioselective synthesis of (S)-equol with the present hydrogenation reaction as a key step was accomplished starting from commercially available starting materials in six steps with 48.4% overall yield. [Copyright &y& Elsevier]

A concise and efficient strategy has been developed to construct a polyketide chain by employing relay asymmetric hydrogenations catalyzed by two chiral spiro iridium catalysts. By using this strategy, an enantioselective total synthesis of (−)‐doliculide has been achieved in 19 steps with 6.9 % overall yield. The route features high enantioselectivity and diastereoselectivity. The catalyst loading can be as low as 0.005 mol‐%. It is convenient to obtain natural polyketides and their analogues by this strategy. [ABSTRACT FROM AUTHOR]

The transition-metal-catalyzed reaction of diazo compounds with arenes or heteroarenes is an efficient and straightforward approach to functionalize aromatic compounds. This digest summarizes recent progresses on transition-metal-catalyzed asymmetric reactions of diazo compounds with electron-rich (hetero-) arenes, including C–H functionalization, cascade reaction, cyclopropanation, cycloaddition, Buchner reaction and intramolecular dearomatization. [ABSTRACT FROM AUTHOR]