Jin Qu

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Name: 渠瑾; Jin Qu

Organization: Nankai University , China

Department: State Key Laboratory and Institute of Elemento-organic Chemistry

Title: Professor(PhD)

TOPICS

Organic Chemistry

Chemicals
References

Molecular Iodine-Mediated α-C–H Oxidation of Pyrrolidines to N,O-Acetals: Synthesis of (±)-Preussin by Late-Stage 2,5-Difunctionalizations of Pyrrolidine

Co-reporter:Hao-Jie Rong, Jun-Jun Yao, Ji-Kun Li, and Jin Qu

The Journal of Organic Chemistry June 2, 2017 Volume 82(Issue 11) pp:5557-5557

Publication Date(Web):May 12, 2017

DOI:10.1021/acs.joc.7b00361

We previously reported an iterative synthesis of unsymmetrical 2,5-disubstituted pyrrolidines from pyrrolidine by two rounds of redox-triggered α-C–H functionalization. Although this approach can be used to introduce substituents at the 2- and 5-positions, it is lengthy because the redox auxiliary must be removed and then reinstalled. Therefore, we sought to develop a method to oxidize 2-functionalized pyrrolidine to cyclic N,O-acetal which could then react with a nucleophile for introduction of the 5-substituent. In this work, we found that molecular iodine can mediate the preferential oxidation of secondary over tertiary α-C–H bonds of α-substituted pyrrolidines to form cyclic N,O-acetals, improving the step economy of our previously reported method. With this strategy, (±)-preussin and its C(3) epimer were synthesized from (±)-pyrrolidin-3-ol.

Synthesis of γ-Lactams by Mild, o-Benzoquinone-Induced Oxidation of Pyrrolidines Containing Oxidation-Sensitive Functional Groups

Co-reporter:Hao-Jie Rong, Yong-Feng Cheng, Fan-Fan Liu, Shu-Jian Ren, and Jin Qu

The Journal of Organic Chemistry 2017 Volume 82(Issue 1) pp:532-540

Publication Date(Web):December 2, 2016

DOI:10.1021/acs.joc.6b02562

The late-stage oxidation of substituted pyrrolidines offers good flexibility for the construction of γ-lactam libraries, and especially in recent years the methods for functionalization of pyrrolidine have been available. We reported a new strategy for oxidation of pyrrolidines to γ-lactams: reaction of pyrrolidine with an o-benzoquinone gives an N,O-acetal by direct oxidation of the α-C–H bond of the pyrrolidine ring, and then the N,O-acetal is further oxidized by the o-benzoquinone to the γ-lactam. Because the first oxidation occurs selectively at the α-C–H of the pyrrolidine ring, oxidation-sensitive functional groups (allyl-, vinyl-, hydroxyl-, and amino groups) on pyrrolidine ring are unaffected. The synthetic utility of this novel method was demonstrated by the facile syntheses of (S)-vigabatrin and two analogues.

Tetraphenylphosphonium Tetrafluoroborate/1,1,1,3,3,3-Hexafluoroisopropanol (Ph4PBF4/HFIP) Effecting Epoxide-Initiated Cation–Olefin Polycyclizations

Co-reporter:Yan Tian; Xin Xu; Lin Zhang

Organic Letters 2016 Volume 18(Issue 2) pp:268-271

Publication Date(Web):January 7, 2016

DOI:10.1021/acs.orglett.5b03438

The use of an excess amount of tetraphenylphosphonium tetrafluoroborate in 1,1,1,3,3,3-hexafluoroisopropanol, which can stabilize the intermediate cation in the reaction, efficiently promoted epoxide-initiated cation–olefin polycyclization reactions with broad functional group tolerance and water and oxygen tolerance.

Ring-Opening/Expansion Rearrangement of Cycloprop[2,3]inden-1-ols Catalyzed by p-Toluenesulfonic Acid

Co-reporter:Pei-Fang Li;Cheng-Bo Yi;Shu-Jian Ren

Advanced Synthesis & Catalysis 2016 Volume 358( Issue 13) pp:2088-2092

Publication Date(Web):

DOI:10.1002/adsc.201600246

Redox-Triggered α-C–H Functionalization of Pyrrolidines: Synthesis of Unsymmetrically 2,5-Disubstituted Pyrrolidines

Co-reporter:Yong-Feng Cheng, Hao-Jie Rong, Cheng-Bo Yi, Jun-Jun Yao, and Jin Qu

Organic Letters 2015 Volume 17(Issue 19) pp:4758-4761

Publication Date(Web):September 17, 2015

DOI:10.1021/acs.orglett.5b02298

By using o-benzoquinone as an internal oxidant, the regio- and diastereoselective functionalization of the secondary over the tertiary α-C–H bond of 2-substituted pyrrolidines is first realized. Subsequent intermolecular addition of a nucleophile to the generated N,O-acetal and cleavage of the aromatic substituent leads to 2,5-disubstituted pyrrolidines.

Hot water-promoted cyclopropylcarbinyl rearrangement facilitates construction of homoallylic alcohols

Co-reporter:Pei-Fang Li, Cheng-Bo Yi and Jin Qu

Organic & Biomolecular Chemistry 2015 vol. 13(Issue 17) pp:5012-5021

Publication Date(Web):18 Mar 2015

DOI:10.1039/C5OB00305A

In refluxing 9:1 (v/v) H2O–1,4-dioxane and without an additional catalyst, the rearrangements of various types of cyclopropyl carbinols were attempted. It was found that the reactions generally gave homoallylic alcohols in good to very high chemical yields. Rearrangements of bicyclic or tricyclic cyclopropyl carbinols readily gave the desired ring-expanded cyclic homoallylic alcohols which are difficult to synthesize by other means.

Intramolecular Etherification and Polyene Cyclization of π-Activated Alcohols Promoted by Hot Water

Co-reporter:Feng-Zhi Zhang, Yan Tian, Guo-Xing Li, and Jin Qu

The Journal of Organic Chemistry 2015 Volume 80(Issue 2) pp:1107-1115

Publication Date(Web):December 19, 2014

DOI:10.1021/jo502636d

Hot water, acting as a mildly acidic catalyst, efficiently promoted intramolecular direct nucleophilic substitution reactions of unsaturated alcohols with heteroatom or carbon nucleophiles. In a mixed solvent of water and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), polyene cyclizations using allylic alcohols as initiators gave the desired cyclized products, and in neat HFIP, a tricyclization reaction gave a tetracyclic product in 51% chemical yield.

Simple and efficient synthesis of tetrahydro-β-carbolines via the Pictet–Spengler reaction in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP)

Co-reporter:Li-Na Wang, Su-Li Shen and Jin Qu

RSC Advances 2014 vol. 4(Issue 58) pp:30733-30741

Publication Date(Web):17 Jul 2014

DOI:10.1039/C4RA03628J

1,1,1,3,3,3-Hexafluoro-2-propanol (HFIP) can act as both the solvent and the catalyst to promote the Pictet–Spengler reactions between tryptamine derivatives and aldehydes or activated ketones. For most substrates, removing the low boiling point HFIP by distillation directly afforded tetrahydro-β-carbolines in high yields.

1,n-Rearrangement of Allylic Alcohols Promoted by Hot Water: Application to the Synthesis of Navenone B, a Polyene Natural Product

Co-reporter:Pei-Fang Li, Heng-Lu Wang, and Jin Qu

The Journal of Organic Chemistry 2014 Volume 79(Issue 9) pp:3955-3962

Publication Date(Web):April 9, 2014

DOI:10.1021/jo5004086

It was reported for the first time that hot water as a mildly acidic catalyst efficiently promoted 1,n-rearrangement (n = 3, 5, 7, 9) of allylic alcohols. In some cases, the rearrangement reactions joined isolated C–C double or triple bonds to generate conjugated polyene or enyne structure motifs. We used the 1,3-rearrangement reaction of an allylic alcohol in hot water as part of an attractive new strategy for construction of the polyene natural product navenone B by iterative use of a Grignard reaction, a 1,3-rearrangement of the resulting allylic alcohol, and subsequent oxidation of the rearranged product.

How Does Aqueous Solubility of Organic Reactant Affect a Water-Promoted Reaction?

Co-reporter:Yi-Jie Zuo and Jin Qu

The Journal of Organic Chemistry 2014 Volume 79(Issue 15) pp:6832-6839

Publication Date(Web):July 7, 2014

DOI:10.1021/jo500733v

It was widely reported that under the “on water” condition, various water-promoted organic reactions can proceed with very high speed. Thus, it is considered that the aqueous solubility of reactant is not an important issue in these reactions. Three types of water-promoted organic reactions were investigated in the current study to distinguish whether the reaction rate of an aqueous reaction was affected by the aqueous solubilities of the reactants. The results showed that, for a Diels–Alder reaction which was fast under the neat conditions, the aqueous solubilities of reactants had little influence on the reaction. However, for the reactions which proceeded slowly under the neat conditions, such as [2σ+2σ+2π] cycloaddition reactions and epoxide aminolysis reactions, the reactants with good aqueous solubilities proceeded fast in water. Poorly aqueous soluble reactants reacted slowly or did not react under the “on water” condition, and an appropriate amount of organic cosolvent was needed to make the reaction become efficient. This evidence suggested that for these two types of reactions, the dissolution of the reactants in water was required.

A Catalyst-Free One-Pot Construction of Skeletons of 5-Methoxyseselin and Alloxanthoxyletin in Water

Co-reporter:Jin-Li Cao, Su-Li Shen, Peng Yang, and Jin Qu

Organic Letters 2013 Volume 15(Issue 15) pp:3856-3859

Publication Date(Web):July 19, 2013

DOI:10.1021/ol401581p

In refluxing water and without an additional catalyst, electron-rich phenols could react with alkynoic acids or alkynoates to provide coumarin structures. The skeletons of two natural pyranocoumarins, 5-methoxyseselin and alloxanthoxyletin, could be constructed (total yield up to 76%) in an aqueous multicomponent reaction in which isoprenyl acetate, propiolic acid, and phloroglucinol were simply mixed and refluxed in water.

Hot Water-Promoted SN1 Solvolysis Reactions of Allylic and Benzylic Alcohols

Co-reporter:Dr. Zhao-Bing Xu ;Dr. Jin Qu

Chemistry - A European Journal 2013 Volume 19( Issue 1) pp:314-323

Publication Date(Web):

DOI:10.1002/chem.201202886

Abstract

During the studies of hydrolysis of epoxides in water, we found that the hydrolysis of (−)-α-pinene oxide at 20 °C gave enantiomerically pure trans-(−)-sobrerol, whereas the same reaction in water heated at reflux unexpectedly gave a racemic mixture of trans- and cis-sobrerol (trans/cis=6:4). We have examined this remarkable difference in detail and found that hot water, whose behavior is quite different compared with room- or high-temperature water, could promote S_N1 solvolysis reactions of allylic alcohols and thus caused the racemization of trans-(−)-sobrerol. The effect of reaction temperature, the addition of organic co-solvent, and the concentration of the solute on the rate of the racemization of trans-(−)-sobrerol were further examined to understand the role that hot water played in the reaction. It was proposed that the catalytic effects of hot water are owing to its mild acidic characteristic, thermal activation, high ionizing power, and better solubility of organic reactant. Further investigation showed that the racemization of other chiral allylic/benzylic alcohols could efficiently proceed in hot water.

Enantioselective Friedel–Crafts reactions between phenols and N-tosylaldimines catalyzed by a leucine-derived bifunctional catalyst

Co-reporter:Guo-Xing Li and Jin Qu

Chemical Communications 2012 vol. 48(Issue 44) pp:5518-5520

Publication Date(Web):17 Apr 2012

DOI:10.1039/C2CC31735D

Enantioselective Friedel–Crafts reactions between phenols and N-tosylaldimines were developed using a bifunctional catalyst readily prepared from L-leucine. The chiral benzylic amine products were obtained in high yields (up to 96% yield) and good to high enantiomeric excesses (up to 95% ee).

Two Concise Enantioselective Total Syntheses of (−)-Glabrescol Implicate Alternative Biosynthetic Pathways Starting from Squalene

Co-reporter:Peng Yang, Pei-Fang Li, Jin Qu, and Liang-Fu Tang

Organic Letters 2012 Volume 14(Issue 15) pp:3932-3935

Publication Date(Web):July 20, 2012

DOI:10.1021/ol3016836

The C2-symmetric (−)-glabrescol was synthesized in two steps from (10S,11R)-dihydroxy-10,11-dihydrosqualene or squalene with 50% or 10% overall yields, respectively. These highly efficient and biomimetic syntheses employed a base-promoted middle-to-terminal double epoxide-opening cascade, which constructs the five tetrahydrofuran rings in glabrescol in one operation.

Water-Promoted Kinetic Separation of trans- and cis-Limonene Oxides

Co-reporter:Zhao-Bing Xu

Chinese Journal of Chemistry 2012 Volume 30( Issue 5) pp:1133-1136

Publication Date(Web):

DOI:10.1002/cjoc.201100455

Abstract

The efficient hydrolytic kinetic separation of trans/cis-(R)-(+)-limonene oxides was realized in a 1:1 mixed solvent of water and 1,4-dioxane without additional catalyst. Optically pure trans-(R)-(+)-limonene oxide was recovered in high yield (77%).

Backbone Modification of β-Hairpin-Forming Tetrapeptides in Asymmetric Acyl Transfer Reactions

Co-reporter:Peng Chen and Jin Qu

The Journal of Organic Chemistry 2011 Volume 76(Issue 9) pp:2994-3004

Publication Date(Web):March 15, 2011

DOI:10.1021/jo200403g

Synthetic oligopeptides as mimics of enzymes have been increasingly exploited as catalysts for asymmetric reactions, but highly effective oligopeptide catalysts with relatively low molecular weight are still in great demand. In this paper, we showed the conformational engineering of the β-hairpin-forming tetrapeptide 4 which was first reported by Miller’s group as the catalyst for the asymmetric acyl transfer reaction of trans-2-(N-acetylamino)cyclohexan-1-ol (krel = 28). Through our backbone modification strategy, thioamide and sulfonamide as the isosteres of amide were introduced in the β-hairpin secondary structure. The thioxo peptides also adopt β-hairpin conformations as the oxopeptide supported by the combined use of NMR, IR, and X-ray techniques. Thioxo tetrapeptide 14 formed a more constrained β-hairpin conformation and therefore delivered much higher enantioselectivity (krel = 109) in the same reaction. Moreover, the examination of the conformational changes of tetrapeptide 8 upon the protonation of the Nπ-methylhistidine moiety provided evidence to explain the variation of its catalytic efficiency in the asymmetric acyl-transfer reaction.

Hot water as a mild Brønsted acid catalyst in ring opening reactions of epoxides

Co-reporter:ZhaoBing Xu

Science China Chemistry 2011 Volume 54( Issue 11) pp:1718-1725

Publication Date(Web):2011 November

DOI:10.1007/s11426-011-4323-x

Ring opening of extremely hydrophobic epoxides with water, amines, sodium azide and thiophenol was realized in the mixture solvent of water and 1, 4-dioxane under reflux condition. Hot water was believed to act as a mild Brønsted acid catalyst in the epoxide-opening reactions.

Friedel–Crafts alkylation of arenes with epoxides promoted by fluorinated alcohols or water

Co-reporter:Guo-Xing Li and Jin Qu

Chemical Communications 2010 vol. 46(Issue 15) pp:2653-2655

Publication Date(Web):10 Mar 2010

DOI:10.1039/B926684D

The stereoselective intra- and intermolecular Friedel–Crafts alkylation of electron-rich arenes with epoxides can take place in refluxing 1,1,1,3,3,3-hexafluoroisopropanol owing to its weak acidity and high ionizing power.

Boiling water-catalyzed neutral and selective N-Boc deprotection

Co-reporter:Jia Wang, Yan-Liang Liang and Jin Qu

Chemical Communications 2009 (Issue 34) pp:5144-5146

Publication Date(Web):31 Jul 2009

DOI:10.1039/B910239F

A general protocol for removing Boc groups from various types of nitrogen is reported and a preliminary investigation of the reaction mechanism indicates that water acts as a dual acid/base catalyst at elevated temperature.

Enantioselective Friedel–Crafts reactions between phenols and N-tosylaldimines catalyzed by a leucine-derived bifunctional catalyst

Co-reporter:Guo-Xing Li and Jin Qu

Chemical Communications 2012 - vol. 48(Issue 44) pp:NaN5520-5520

Publication Date(Web):2012/04/17

DOI:10.1039/C2CC31735D

Friedel–Crafts alkylation of arenes with epoxides promoted by fluorinated alcohols or water

Co-reporter:Guo-Xing Li and Jin Qu

Chemical Communications 2010 - vol. 46(Issue 15) pp:NaN2655-2655

Publication Date(Web):2010/03/10

DOI:10.1039/B926684D

Boiling water-catalyzed neutral and selective N-Boc deprotection

Co-reporter:Jia Wang, Yan-Liang Liang and Jin Qu