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Li-Xin Dai

Bio: Li-Xin Dai is an academic researcher from Chinese Academy of Sciences. The author has contributed to research in topics: Enantioselective synthesis & Allylic rearrangement. The author has an hindex of 54, co-authored 284 publications receiving 8151 citations. Previous affiliations of Li-Xin Dai include Hong Kong University of Science and Technology & Dalian Institute of Chemical Physics.


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Journal ArticleDOI
Li-Xin Dai1, Tao Tu1, Shu-Li You1, Wei-Ping Deng1, Xue-Long Hou1 
TL;DR: The advantages of using ferrocene as a scaffold for chiral ligands are described, particularly those regarding planar chirality, rigid bulkiness, and ease of derivatization.
Abstract: Chiral ferrocene ligands have been widely used in asymmetric catalysis. The advantages of using ferrocene as a scaffold for chiral ligands are described, particularly those regarding planar chirality, rigid bulkiness, and ease of derivatization. The role of planar chirality in 1,2- and 1,1¢-disubstituted ferrocene systems is discussed. By using a bulky ferrocene fragment, novel ferrocene ligands were designed, and high enantioselectivity and regioselectivity were achieved in the allylic substitution reaction of monosubstituted allyl substrates. Using the tunable electronic properties of a diphosphine-oxazoline ferrocenyl ligand, the regioselectivity of the intermolecular asymmetric Heck reaction was also examined.

503 citations

Journal ArticleDOI
TL;DR: By a sidearm approach, camphor-derived sulfur ylides 1 were designed and synthesized for the cyclopropanation of electron-deficient alkenes and epoxidation of aldehydes and the sidearmed hydroxyl group was found to play a key role in the control of enantioselectivity and diastereoselectivities.
Abstract: By a sidearm approach, camphor-derived sulfur ylides 1 were designed and synthesized for the cyclopropanation of electron-deficient alkenes and epoxidation of aldehydes. Under the optimal conditions, the exo-type sulfonium salts 4a and 4b reacted with β-aryl-α,β-unsaturated esters, amides, ketones, and nitriles to give 1,3-disubstituted-2-vinylcyclopropanes with high diastereoselectivities and enantioselectivities. When the endo-type sulfonium salts 5a and 5b were used, the diastereoselectivities were not changed, whereas the absolute configurations of the products became the opposite to those of the reactions of 4a and 4b. An ylide cyclopropanation of chalcone derivatives with phenylvinyl bromide in the presence of catalytic amount of chiral sulfonium salts 4b and 5b has been developed. The sidearmed hydroxyl group was found to play a key role in the control of enantioselectivity and diastereoselectivity. The origins of the high diastereoselectivity and enantioselectivity were also studied by density fun...

163 citations

Journal ArticleDOI
TL;DR: An Ir-catalyzed allylic vinylation reaction of allyl carbonates with o-aminostyrene derivatives has been realized, providing skipped (Z,E)-diene derivatives, and the results suggest that the leaving group of the allylic precursor plays a key role in directing the reaction pathway.
Abstract: An Ir-catalyzed allylic vinylation reaction of allyl carbonates with o-aminostyrene derivatives has been realized, providing skipped (Z,E)-diene derivatives. With (E)-but-2-ene-1,4-diyl dimethyl dicarbonate as the substrate, an efficient enantioselective synthesis of 1-benzazepine derivatives via an Ir-catalyzed domino allylic vinylation/intramolecular allylic amination reaction has been developed. Mechanistic studies of the allylic vinylation reaction have been carried out, and the results suggest that the leaving group of the allylic precursor plays a key role in directing the reaction pathway. Screening of various allylic precursors showed that Ir-catalyzed reactions of allyl diethyl phosphates with o-aminostyrene derivatives proceed via an allylic amination pathway. A subsequent ring-closing metathesis (RCM) reaction of the amination products led to a series of enantiomerically enriched 1,2-dihydroquinoline derivatives. Their utility is indicated by an asymmetric total synthesis of (−)-angustureine.

159 citations

Journal ArticleDOI
TL;DR: Mechanistic studies, including DFT calculations and X-ray crystallographic analyses of the (π-allyl)-Ir complexes, reveal that the active iridacycle is formed via C(sp(2))-H bond activation.
Abstract: A series of N-aryl phosphoramidite ligands has been synthesized and applied to iridium-catalyzed allylic alkylation reactions, offering high regio- and enantioselectivities for a wide variety of substrates. These ligands feature the synthetic convenience and good tolerance of the ortho-substituted cinnamyl carbonates. Mechanistic studies, including DFT calculations and X-ray crystallographic analyses of the (π-allyl)–Ir complexes, reveal that the active iridacycle is formed via C(sp2)–H bond activation.

156 citations


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TL;DR: Alkylations with Phenols, Nitrogen Nucleophiles in AAA Total Synthesis, and Considerations for Enantioselective Allylic Alkylation are presented.
Abstract: A. Primary Alcohols as Nucleophiles 2931 B. Carboxylates as Nucleophiles 2931 C. Alkylations with Phenols 2932 IV. Nitrogen Nucleophiles in AAA Total Synthesis 2935 A. Alkylamines as Nucleophiles 2935 B. Azides as a Nucleophile 2936 C. Sulfonamide Nucleophiles 2937 D. Imide Nucleophiles 2938 E. Heterocyclic Amine Nucleophiles 2940 V. Sulfur Nucleophiles 2941 VI. Summary and Conclusions 2941 VII. Acknowledgment 2941 VIII. References 2942 I. Considerations for Enantioselective Allylic Alkylation

2,230 citations

Journal ArticleDOI
TL;DR: A new iron(III) halide-promoted aza-Prins cyclization between γ,δ-unsaturated tosylamines and aldehydes provides six-membered azacycles in good to excellent yields.
Abstract: A new iron(III) halide-promoted aza-Prins cyclization between γ,δ-unsaturated tosylamines and aldehydes provides six-membered azacycles in good to excellent yields. The process is based on the consecutive generation of γ-unsaturated-iminium ion and further nucleophilic attack by the unsaturated carbon−carbon bond. Homoallyl tosylamine leads to trans-2-alkyl-4-halo-1-tosylpiperidine as the major isomer. In addition, the alkyne aza-Prins cyclization between homopropargyl tosylamine and aldehydes gives 2-alkyl-4-halo-1-tosyl-1,2,5,6-tetrahydropyridines as the only cyclic products. The piperidine ring is widely distributed throughout Nature, e.g., in alkaloids,1 and is an important scaffold for drug discovery, being the core of many pharmaceutically significant compounds.2,3 The syntheses of these type of compounds have been extensively studied in the development of new drugs containing six-membered-ring heterocycles.4 Reactions between N-acyliminium ions and nucleophiles, also described as amidoalkylation or Mannich-type condensations, have been frequently used to introduce substituents at the R-carbon of an amine.5 There are several examples that involve an intramolecular attack of a nucleophilic olefin into an iminium cation for the construction of a heterocyclic ring system.6 Traditionally, the use of hemiaminals or their derivatives as precursors of N-acyliminium intermediates has been a common two-step strategy in these reactions.6a Among this type of cyclization is the aza-Prins cyclization,7 which uses alkenes as intramolecular nucleophile. However, cy† X-ray analysis. E-mail address: malopez@ull.es. (1) (a) Fodor, G. B.; Colasanti, B. Alkaloids: Chemical and Biological PerspectiVes; Pelletier, S. W., Ed.; Wiley: New York, 1985; Vol. 23, pp 1-90. (b) Baliah, V.; Jeyarama, R.; Chandrasekaran, L. Chem. ReV. 1983, 83, 379-423. (2) Watson, P. S.; Jiang, B.; Scott, B. Org. Lett. 2000, 2, 3679-3681. (3) Horton, D. A.; Bourne, G. T.; Smythe, M. L. Chem. ReV. 2003, 103, 893-930. (4) Buffat, M. G. P. Tetrahedron 2004, 60, 1701-1729 and references therein. (5) Speckamp, W. N.; Moolenaar, M. J. Tetrahedron 2000, 56, 3187- 3856 and references therein. (6) (a) Hiemstra, H.; Speckamp, W. N. In ComprehensiVe Organic Synthesis; Trost, B. M., Fleming, O., Heathcock, C. H., Eds.; Pergamon: New York, 1991; Vol. 2, pp 1047-1081. (b) Speckamp, W. N.; Hiemstra, H. Tetrahedron 1985, 41, 4367-4416. (7) (a) Dobbs, A. P.; Guesne, S. J. J.; Hursthouse, M. B.; Coles, S. J. Synlett 2003, 11, 1740-1742. (b) Dobbs, A. P.; Guesne, S. J. J.; Martinove, S.; Coles, S. J.; Hursthouse, M. B. J. Org. Chem. 2003, 68, 7880-7883. (c) Hanessian, S.; Tremblay, M.; Petersen, F. W. J. Am. Chem. Soc. 2004, 126, 6064-6071 and references therein. (d) Dobbs, A. P.; Guesne, S. J. Synlett 2005, 13, 2101-2103. ORGANIC

1,854 citations

Journal ArticleDOI
TL;DR: This review will focus mainly on the new methods that have appeared in the literature since 1989 for stereoselective cyclopropanation reactions from olefins: the halomethylmetal-mediated cycloalkane reactions, the transition metal-catalyzed decomposition of diazo compounds, and the nucleophilic addition-ring closure sequence.
Abstract: Organic chemists have always been fascinated by the cyclopropane subunit.1 The smallest cycloalkane is found as a basic structural element in a wide range of naturally occurring compounds.2 Moreover, many cyclopropane-containing unnatural products have been prepared to test the bonding features of this class of highly strained cycloalkanes3 and to study enzyme mechanism or inhibition.4 Cyclopropanes have also been used as versatile synthetic intermediates in the synthesis of more functionalized cycloalkanes5,6 and acyclic compounds.7 In recent years, most of the synthetic efforts have focused on the enantioselective synthesis of cyclopropanes.8 This has remained a challenge ever since it was found that the members of the pyrethroid class of compounds were effective insecticides.9 New and more efficient methods for the preparation of these entities in enantiomerically pure form are still evolving, and this review will focus mainly on the new methods that have appeared in the literature since 1989. It will elaborate on only three types of stereoselective cyclopropanation reactions from olefins: the halomethylmetal-mediated cyclopropanation reactions (eq 1), the transition metal-catalyzed decomposition of diazo compounds (eq 2), and the nucleophilic addition-ring closure sequence (eqs 3 and 4). These three processes will be examined in the context of diastereoand enantiocontrol. In the last section of the review, other methods commonly used to make chiral, nonracemic cyclopropanes will be briefly outlined.

1,426 citations

Journal ArticleDOI
TL;DR: A review on metal ion containing coordination polymer networks is given in this paper, where the authors highlight the current research in the field by giving a short overview on the concept of coordination polymers networks, how and why they are made.

1,361 citations