Hao Xu

Name: Xu, Hao

Organization: Georgia State University , USA

Department: Department of Chemistry

Title: Assistant Professor(PhD)

Chemicals
References

Process Safety Assessment of the Iron-Catalyzed Direct Olefin Diazidation for the Expedient Synthesis of Vicinal Primary Diamines

Co-reporter:Hai-Tao Zhu, Luca Arosio, Roberto Villa, Marino Nebuloni, and Hao Xu

Organic Process Research & Development December 15, 2017 Volume 21(Issue 12) pp:2068-2068

Publication Date(Web):November 8, 2017

DOI:10.1021/acs.oprd.7b00312

We report herein a process safety assessment of the iron-catalyzed direct olefin diazidation for the preparation of a broad range of synthetically valuable vicinal primary diamines. Differential scanning calorimetry analysis of the corresponding reagents, intermediates, and a list of representative diazide/diaminium salt products revealed that all of them are thermal stable at the reaction temperature. The drop weight test of the diazides suggested that they are moderately impact-sensitive. Guided by this assessment, an optimized olefin diazidation/diamination procedure has been developed which allows for the gram-scale diaminium salt synthesis without purification of the diazide intermediate.

Iron(II)-Catalyzed Intermolecular Aminofluorination of Unfunctionalized Olefins Using Fluoride Ion

Co-reporter:Deng-Fu Lu, Cheng-Liang Zhu, Jeffrey D. Sears, and Hao Xu

Journal of the American Chemical Society 2016 Volume 138(Issue 35) pp:11360-11367

Publication Date(Web):August 16, 2016

DOI:10.1021/jacs.6b07221

We herein report a new catalytic method for intermolecular olefin aminofluorination using earth-abundant iron catalysts and nucleophilic fluoride ion. This method tolerates a broad range of unfunctionalized olefins, especially nonstyrenyl olefins that are incompatible with existing olefin aminofluorination methods. This new iron-catalyzed process directly converts readily available olefins to internal vicinal fluoro carbamates with high regioselectivity (N vs F), many of which are difficult to prepare using known methods. Preliminary mechanistic studies demonstrate that it is possible to exert asymmetric induction using chiral iron catalysts and that both an iron-nitrenoid and carbocation species may be reactive intermediates.

Iron-Catalyzed Direct Diazidation for a Broad Range of Olefins

Co-reporter:Yong-An Yuan;Deng-Fu Lu;Yun-Rong Chen ; Hao Xu

Angewandte Chemie 2016 Volume 128( Issue 2) pp:544-548

Publication Date(Web):

DOI:10.1002/ange.201507550

Abstract

Reported herein is a new iron-catalyzed diastereoselective olefin diazidation reaction which occurs at room temperature (1–5 mol % of catalysts and d.r. values of up to >20:1). This method tolerates a broad range of both unfunctionalized and highly functionalized olefins, including those that are incompatible with existing methods. It also provides a convenient approach to vicinal primary diamines as well as other synthetically valuable nitrogen-containing building blocks which are difficult to obtain with alternative methods. Preliminary mechanistic studies suggest that the reaction may proceed through a new mechanistic pathway in which both Lewis acid activation and iron-enabled redox-catalysis are crucial for selective azido-group transfer.

Iron-Catalyzed Direct Diazidation for a Broad Range of Olefins

Co-reporter:Yong-An Yuan;Deng-Fu Lu;Yun-Rong Chen ; Hao Xu

Angewandte Chemie International Edition 2016 Volume 55( Issue 2) pp:534-538

Publication Date(Web):

DOI:10.1002/anie.201507550

Abstract

Iron(II)-catalyzed asymmetric intramolecular olefin aminochlorination using chloride ion

Co-reporter:Cheng-Liang Zhu, Jun-Shan Tian, Zhen-Yuan Gu, Guo-Wen Xing and Hao Xu

Chemical Science 2015 vol. 6(Issue 5) pp:3044-3050

Publication Date(Web):13 Mar 2015

DOI:10.1039/C5SC00221D

An iron-catalyzed enantioselective and diastereoselective intramolecular olefin aminochlorination reaction is reported (ee up to 92%, dr up to 15:1). In this reaction, a functionalized hydroxylamine and chloride ion are utilized as nitrogen and chlorine sources, respectively. This new method tolerates a range of synthetically valuable internal olefins that are all incompatible with existing asymmetric olefin aminochlorination methods.

Iron(II)-Catalyzed Intermolecular Amino-Oxygenation of Olefins through the N–O Bond Cleavage of Functionalized Hydroxylamines

Co-reporter:Deng-Fu Lu ; Cheng-Liang Zhu ; Zhen-Xin Jia

Journal of the American Chemical Society 2014 Volume 136(Issue 38) pp:13186-13189

Publication Date(Web):August 28, 2014

DOI:10.1021/ja508057u

An iron-catalyzed diastereoselective intermolecular olefin amino-oxygenation reaction is reported, which proceeds via an iron-nitrenoid generated by the N–O bond cleavage of a functionalized hydroxylamine. In this reaction, a bench-stable hydroxylamine derivative is used as the amination reagent and oxidant. This method tolerates a range of synthetically valuable substrates that have been all incompatible with existing amino-oxygenation methods. It can also provide amino alcohol derivatives with regio- and stereochemical arrays complementary to known amino-oxygenation methods.

Iron(II)-Catalyzed Intramolecular Olefin Aminofluorination

Co-reporter:Deng-Fu Lu, Guan-Sai Liu, Cheng-Liang Zhu, Bo Yuan, and Hao Xu

Organic Letters 2014 Volume 16(Issue 11) pp:2912-2915

Publication Date(Web):May 14, 2014

DOI:10.1021/ol501051p

An iron(II)-catalyzed diastereoselective olefin aminofluorination is reported (dr up to >20:1). This new transformation applies a functionalized hydroxylamine and Et3N·3HF as the nitrogen and fluorine source, which facilitates the efficient synthesis of β-fluoro primary amines and amino acids from allylic alcohol derivatives. Preliminary mechanistic studies reveal that an iron–nitrenoid is a possible intermediate and that its reactivity and enantioselectivity can be efficiently modulated by ligands.

Iron(II)-Catalyzed Intramolecular Aminohydroxylation of Olefins with Functionalized Hydroxylamines

Co-reporter:Guan-Sai Liu ; Yong-Qiang Zhang ; Yong-An Yuan

Journal of the American Chemical Society 2013 Volume 135(Issue 9) pp:3343-3346

Publication Date(Web):February 12, 2013

DOI:10.1021/ja311923z

A diastereoselective aminohydroxylation of olefins with a functionalized hydroxylamine is catalyzed by new iron(II) complexes. This efficient intramolecular process readily affords synthetically useful amino alcohols with excellent selectivity (dr up to > 20:1). Asymmetric catalysis with chiral iron(II) complexes and preliminary mechanistic studies reveal an iron nitrenoid is a possible intermediate that can undergo either aminohydroxylation or aziridination, and the selectivity can be controlled by careful selection of counteranion/ligand combinations.

Copper(I)-catalyzed diastereoselective hydroxytrifluoromethylation of dienes accelerated by phosphine ligands

Co-reporter:Deng-Fu Lu, Cheng-Liang Zhu and Hao Xu

Chemical Science 2013 vol. 4(Issue 6) pp:2478-2482

Publication Date(Web):20 Mar 2013

DOI:10.1039/C3SC50582K

A diastereoselective 1,4-hydroxytrifluoromethylation of dienes is catalyzed by copper cyanide–phosphine complexes. This reaction is significantly accelerated by bulky monodentate phosphines, and the discovery enables expedient access to a variety of CF3-containing allylic alcohol derivatives.

Iron(II)-Catalyzed Asymmetric Intramolecular Aminohydroxylation of Indoles

Co-reporter:Yong-Qiang Zhang, Yong-An Yuan, Guan-Sai Liu, and Hao Xu

Organic Letters 2013 Volume 15(Issue 15) pp:3910-3913

Publication Date(Web):July 22, 2013

DOI:10.1021/ol401666e

An enantioselective intramolecular indole aminohydroxylation reaction is catalyzed by iron(II)–chiral bisoxazoline (BOX) complexes (ee up to 99%, dr > 20:1). This discovery enables expedient asymmetric synthesis of a series of biologically active 3-amino oxindoles and 3-amino indolanes.

Copper(II)-catalyzed trifluoromethylation of N-aryl imines

Co-reporter:Yong-Qiang Zhang, Ji-Dan Liu and Hao Xu

Organic & Biomolecular Chemistry 2013 vol. 11(Issue 37) pp:6242-6245

Publication Date(Web):24 Jul 2013

DOI:10.1039/C3OB41283K

Methods for imine trifluoromethylation are of great importance because amines with trifluoromethylated stereogenic centers are useful building blocks for synthetic chemistry and drug discovery. Herein, we describe a new copper(II)-catalyzed imine trifluoromethylation method without the use of Lewis base activators, presumably through cooperative activation.

Highly Enantioselective Cyclizations of Conjugated Trienes with Low Catalyst Loadings: A Robust Chiral N-Heterocyclic Carbene Enabled by Acetic Acid Cocatalyst

Co-reporter:Guansai Liu, Phillip D. Wilkerson, Christopher A. Toth, and Hao Xu

Organic Letters 2012 Volume 14(Issue 3) pp:858-861

Publication Date(Web):January 20, 2012

DOI:10.1021/ol203375y

Densely functionalized cyclopentenones are useful synthetic intermediates. We report herein a new method to synthesize this important class of compounds through a highly enantioselective (98 → 99% ee) triene cyclization that is cocatalyzed by acetic acid and a chiral N-heterocyclic carbene (NHC). We discovered that acetic acid not only could coexist with NHCs but also could greatly stabilize the active catalyst, which enables a long-lived catalyst with high reactivity and selectivity.

Iron(II)-catalyzed asymmetric intramolecular olefin aminochlorination using chloride ion

Co-reporter:Cheng-Liang Zhu, Jun-Shan Tian, Zhen-Yuan Gu, Guo-Wen Xing and Hao Xu

Chemical Science (2010-Present) 2015 - vol. 6(Issue 5) pp:NaN3050-3050

Publication Date(Web):2015/03/13