1
|
Direct bromodeboronation of arylboronic acids with CuBr2 in water. Tetrahedron Lett 2021. [DOI: 10.1016/j.tetlet.2020.152738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
2
|
Shaughnessy KH. Monodentate Trialkylphosphines: Privileged Ligands in Metal-catalyzed Crosscoupling Reactions. CURR ORG CHEM 2020. [DOI: 10.2174/1385272824666200211114540] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Phosphines are widely used ligands in transition metal-catalyzed reactions.
Arylphosphines, such as triphenylphosphine, were among the first phosphines to show
broad utility in catalysis. Beginning in the late 1990s, sterically demanding and electronrich
trialkylphosphines began to receive attention as supporting ligands. These ligands
were found to be particularly effective at promoting oxidative addition in cross-coupling
of aryl halides. With electron-rich, sterically demanding ligands, such as tri-tertbutylphosphine,
coupling of aryl bromides could be achieved at room temperature. More
importantly, the less reactive, but more broadly available, aryl chlorides became accessible
substrates. Tri-tert-butylphosphine has become a privileged ligand that has found application
in a wide range of late transition-metal catalyzed coupling reactions. This success
has led to the use of numerous monodentate trialkylphosphines in cross-coupling reactions. This review
will discuss the general properties and features of monodentate trialkylphosphines and their application in
cross-coupling reactions of C–X and C–H bonds.
Collapse
Affiliation(s)
- Kevin H. Shaughnessy
- Department of Chemistry & Biochemistry, The University of Alabama, Box 870336, Tuscaloosa, AL, 35487-0336, United States
| |
Collapse
|
3
|
Kaiser D, Klose I, Oost R, Neuhaus J, Maulide N. Bond-Forming and -Breaking Reactions at Sulfur(IV): Sulfoxides, Sulfonium Salts, Sulfur Ylides, and Sulfinate Salts. Chem Rev 2019; 119:8701-8780. [PMID: 31243998 PMCID: PMC6661881 DOI: 10.1021/acs.chemrev.9b00111] [Citation(s) in RCA: 440] [Impact Index Per Article: 88.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Indexed: 12/13/2022]
Abstract
Organosulfur compounds have long played a vital role in organic chemistry and in the development of novel chemical structures and architectures. Prominent among these organosulfur compounds are those involving a sulfur(IV) center, which have been the subject of countless investigations over more than a hundred years. In addition to a long list of textbook sulfur-based reactions, there has been a sustained interest in the chemistry of organosulfur(IV) compounds in recent years. Of particular interest within organosulfur chemistry is the ease with which the synthetic chemist can effect a wide range of transformations through either bond formation or bond cleavage at sulfur. This review aims to cover the developments of the past decade in the chemistry of organic sulfur(IV) molecules and provide insight into both the wide range of reactions which critically rely on this versatile element and the diverse scaffolds that can thereby be synthesized.
Collapse
Affiliation(s)
- Daniel Kaiser
- Institute
of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090 Vienna, Austria
| | - Immo Klose
- Institute
of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090 Vienna, Austria
| | - Rik Oost
- Institute
of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090 Vienna, Austria
| | - James Neuhaus
- Institute
of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090 Vienna, Austria
| | - Nuno Maulide
- Institute
of Organic Chemistry, University of Vienna, Währinger Strasse 38, 1090 Vienna, Austria
| |
Collapse
|
4
|
Boultwood T, Bull JA. Synthesis of Selenoaziridines: A Study on Stereochemical Outcomes of the Reaction of Aziridine Radicals and Anions Generated from Iodoaziridines. ACS OMEGA 2019; 4:870-879. [PMID: 31459364 PMCID: PMC6648590 DOI: 10.1021/acsomega.8b03019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 12/26/2018] [Indexed: 06/10/2023]
Abstract
The synthesis of a new functional group in the form of selenyl-substituted aziridines is described. Selenoaziridines are stereoselectively prepared by functionalization of intact aziridine precursors involving radical and anionic intermediates. Radicals are generated from cis-N-Ts iodoaziridines by activation of the C-I bond using alkoxides as a source of single electrons. These form predominantly trans-substituted selenoaziridines dependent on the size of the diselenide. cis-Aziridinyllithiums generated by Li-I exchange also react with diselenides stereospecifically to form a range of cis-selenoaziridines. Proposals for the stereochemical outcome are presented.
Collapse
Affiliation(s)
- Tom Boultwood
- Department
of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 0BZ, U.K.
| | - James A. Bull
- Department
of Chemistry, Imperial College London, Molecular Sciences Research Hub, White City Campus, Wood Lane, London W12 0BZ, U.K.
| |
Collapse
|
5
|
Ziegler DS, Wei B, Knochel P. Improving the Halogen–Magnesium Exchange by using New Turbo‐Grignard Reagents. Chemistry 2018; 25:2695-2703. [DOI: 10.1002/chem.201803904] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Indexed: 12/18/2022]
Affiliation(s)
- Dorothée S. Ziegler
- Department Chemie Ludwig-Maximilians-Universität München Butenandtstrasse 5-13, Haus F 81377 München Germany
| | - Baosheng Wei
- Department Chemie Ludwig-Maximilians-Universität München Butenandtstrasse 5-13, Haus F 81377 München Germany
| | - Paul Knochel
- Department Chemie Ludwig-Maximilians-Universität München Butenandtstrasse 5-13, Haus F 81377 München Germany
| |
Collapse
|
6
|
Huang J, Ouyang L, Li J, Zheng J, Yan W, Wu W, Jiang H. B 2pin 2-Mediated Palladium-Catalyzed Diacetoxylation of Aryl Alkenes with O 2 as Oxygen Source and Sole Oxidant. Org Lett 2018; 20:5090-5093. [PMID: 30118237 DOI: 10.1021/acs.orglett.8b01806] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A novel palladium-catalyzed alkene diacetoxylation with dioxygen (O2) as both the sole oxidant and oxygen source is developed, which was identified by 18O-isotope labeling studies. Control experiments suggested that bis(pinacolato)diboron (B2pin2) played a dominant intermediary role in the formation of a C-O bond. This method performed good functional group tolerance with moderate to excellent yields, which could be successfully applied to the late-stage modification of natural products. Furthermore, an atmospheric pressure of dioxygen enhances the practicability of the protocol.
Collapse
Affiliation(s)
- Jiuzhong Huang
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering , South China University of Technology , Guangzhou 510640 , P. R. China
| | - Lu Ouyang
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering , South China University of Technology , Guangzhou 510640 , P. R. China
| | - Jianxiao Li
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering , South China University of Technology , Guangzhou 510640 , P. R. China
| | - Jia Zheng
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering , South China University of Technology , Guangzhou 510640 , P. R. China
| | - Wuxin Yan
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering , South China University of Technology , Guangzhou 510640 , P. R. China
| | - Wanqing Wu
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering , South China University of Technology , Guangzhou 510640 , P. R. China
| | - Huanfeng Jiang
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering , South China University of Technology , Guangzhou 510640 , P. R. China
| |
Collapse
|
7
|
Nelson DJ, Cazin CSJ, Nolan SP. Grignard Reagents and Palladium. PHYSICAL SCIENCES REVIEWS 2018. [DOI: 10.1515/psr-2016-0018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- David J. Nelson
- WestCHEM Department of Pure & Applied Chemistry University of Strathclyde 295 Cathedral Street Glasgow Lanarkshire , G1 1XL UK
| | - Catherine S. J. Cazin
- EaStCHEM School of Chemistry University of St Andrews Purdie Building North Haugh St Andrews Fife , KY16 9ST UK
| | - Steven P. Nolan
- Department of Inorganic and Physical Chemistry Ghent University Krijgslaan 281 - S3, 9000 Gent , Belgium
| |
Collapse
|
8
|
Chawner SJ, Cases‐Thomas MJ, Bull JA. Divergent Synthesis of Cyclopropane-Containing Lead-Like Compounds, Fragments and Building Blocks through a Cobalt Catalyzed Cyclopropanation of Phenyl Vinyl Sulfide. European J Org Chem 2017; 2017:5015-5024. [PMID: 28983191 PMCID: PMC5601191 DOI: 10.1002/ejoc.201701030] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Indexed: 01/08/2023]
Abstract
Cyclopropanes provide important design elements in medicinal chemistry and are widely present in drug compounds. Here we describe a strategy and extensive synthetic studies for the preparation of a diverse collection of cyclopropane-containing lead-like compounds, fragments and building blocks exploiting a single precursor. The bifunctional cyclopropane (E/Z)-ethyl 2-(phenylsulfanyl)-cyclopropane-1-carboxylate was designed to allow derivatization through the ester and sulfide functionalities to topologically varied compounds designed to fit in desirable chemical space for drug discovery. A cobalt-catalyzed cyclopropanation of phenyl vinyl sulfide affords these scaffolds on multigram scale. Divergent, orthogonal derivatization is achieved through hydrolysis, reduction, amidation and oxidation reactions as well as sulfoxide-magnesium exchange/functionalization. The cyclopropyl Grignard reagent formed from sulfoxide exchange is stable at 0 °C for > 2 h, which enables trapping with various electrophiles and Pd-catalyzed Negishi cross-coupling reactions. The library prepared, as well as a further virtual elaboration, is analyzed against parameters of lipophilicity (ALog P), MW and molecular shape by using the LLAMA (Lead-Likeness and Molecular Analysis) software, to illustrate the success in generating lead-like compounds and fragments.
Collapse
Affiliation(s)
- Stephen J. Chawner
- Department of ChemistryImperial College LondonSouth KensingtonSW7 2AZLondonUK
| | - Manuel J. Cases‐Thomas
- Lilly Research CentreEli Lilly and CompanyErl Wood Manor, Sunninghill RoadGU20 6PHWindleshamUK
| | - James A. Bull
- Department of ChemistryImperial College LondonSouth KensingtonSW7 2AZLondonUK
| |
Collapse
|
9
|
Eremin DB, Ananikov VP. Understanding active species in catalytic transformations: From molecular catalysis to nanoparticles, leaching, “Cocktails” of catalysts and dynamic systems. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2016.12.021] [Citation(s) in RCA: 243] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
10
|
Barrett MJ, Khan GF, Davies PW, Grainger RS. Alkynyl sulfoxides as α-sulfinyl carbene equivalents: gold-catalysed oxidative cyclopropanation. Chem Commun (Camb) 2017; 53:5733-5736. [DOI: 10.1039/c7cc02244a] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Gold catalysed oxidation of alkynyl sulfoxides provides access to a desirable α-sulfinyl metal carbene reactivity profile that is inaccessible using diazo chemistry.
Collapse
|
11
|
Boultwood T, Affron DP, Bull JA. Studies on the synthesis of α-iodoaziridines and improved conditions for the synthesis of alkyl-α-iodoaziridines using ClMgCHI2. Tetrahedron 2015. [DOI: 10.1016/j.tet.2015.05.098] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
12
|
Li-Yuan Bao R, Zhao R, Shi L. Progress and developments in the turbo Grignard reagent i-PrMgCl·LiCl: a ten-year journey. Chem Commun (Camb) 2015; 51:6884-900. [DOI: 10.1039/c4cc10194d] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The structural and kinetic perspectives of i-PrMgCl·LiCl help to rationalize the trends of its unique reactivity and selectivity.
Collapse
Affiliation(s)
- Robert Li-Yuan Bao
- Institute of Organic Chemistry
- The Academy of Fundamental and Interdisciplinary Science
- Harbin Institute of Technology
- Harbin 150080
- P. R. China
| | - Rong Zhao
- Institute of Organic Chemistry
- The Academy of Fundamental and Interdisciplinary Science
- Harbin Institute of Technology
- Harbin 150080
- P. R. China
| | - Lei Shi
- Institute of Organic Chemistry
- The Academy of Fundamental and Interdisciplinary Science
- Harbin Institute of Technology
- Harbin 150080
- P. R. China
| |
Collapse
|
13
|
|
14
|
Alwedi E, Zakharov LN, Blakemore PR. Chain Extension of Boronic Esters with Lithiooxiranes Generated by Sulfoxide-Metal Exchange - Stereocontrolled Access to 2°/2°, 2°/3°, and 3°/3° Vicinal Diols and Related Compounds. European J Org Chem 2014. [DOI: 10.1002/ejoc.201403105] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
15
|
Rayner PJ, Gelardi G, O'Brien P, Horan RAJ, Blakemore DC. On the synthesis of α-amino sulfoxides. Org Biomol Chem 2014; 12:3499-512. [PMID: 24759885 DOI: 10.1039/c4ob00567h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
A synthetic study on the preparation of N-Boc α-amino sulfoxides has revealed an unexpected instability which is believed to be due to α-elimination of the sulfoxide to give an iminium ion. Full synthetic details are reported on two main synthetic routes: lithiation and sulfinate trapping of N-Boc heterocycles and oxidation of N-Boc α-amino sulfides. Six novel α-amino sulfoxides were successfully prepared and isolated. It is speculated that four other α-amino sulfoxides were synthesised but could not be isolated due to their propensity to α-eliminate the sulfoxide. Ultimately, a stable, cyclic N-Boc α-amino sulfoxide was prepared and this successful synthesis relied on the α-amino sulfoxide being part of a bicyclic [3.1.0] fused ring system that could not undergo α-elimination of the sulfoxide.
Collapse
Affiliation(s)
- Peter J Rayner
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
| | | | | | | | | |
Collapse
|
16
|
Boultwood T, Affron DP, Bull JA. Synthesis and purification of iodoaziridines involving quantitative selection of the optimal stationary phase for chromatography. J Vis Exp 2014. [PMID: 24893769 DOI: 10.3791/51633] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The highly diastereoselective preparation of cis-N-Ts-iodoaziridines through reaction of diiodomethyllithium with N-Ts aldimines is described. Diiodomethyllithium is prepared by the deprotonation of diiodomethane with LiHMDS, in a THF/diethyl ether mixture, at -78 °C in the dark. These conditions are essential for the stability of the LiCHI2 reagent generated. The subsequent dropwise addition of N-Ts aldimines to the preformed diiodomethyllithium solution affords an amino-diiodide intermediate, which is not isolated. Rapid warming of the reaction mixture to 0 °C promotes cyclization to afford iodoaziridines with exclusive cis-diastereoselectivity. The addition and cyclization stages of the reaction are mediated in one reaction flask by careful temperature control. Due to the sensitivity of the iodoaziridines to purification, assessment of suitable methods of purification is required. A protocol to assess the stability of sensitive compounds to stationary phases for column chromatography is described. This method is suitable to apply to new iodoaziridines, or other potentially sensitive novel compounds. Consequently this method may find application in range of synthetic projects. The procedure involves firstly the assessment of the reaction yield, prior to purification, by (1)H NMR spectroscopy with comparison to an internal standard. Portions of impure product mixture are then exposed to slurries of various stationary phases appropriate for chromatography, in a solvent system suitable as the eluent in flash chromatography. After stirring for 30 min to mimic chromatography, followed by filtering, the samples are analyzed by (1)H NMR spectroscopy. Calculated yields for each stationary phase are then compared to that initially obtained from the crude reaction mixture. The results obtained provide a quantitative assessment of the stability of the compound to the different stationary phases; hence the optimal can be selected. The choice of basic alumina, modified to activity IV, as a suitable stationary phase has allowed isolation of certain iodoaziridines in excellent yield and purity.
Collapse
Affiliation(s)
| | | | - James A Bull
- Department of Chemistry, Imperial College London;
| |
Collapse
|
17
|
Degennaro L, Trinchera P, Luisi R. Recent advances in the stereoselective synthesis of aziridines. Chem Rev 2014; 114:7881-929. [PMID: 24823261 DOI: 10.1021/cr400553c] [Citation(s) in RCA: 320] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Leonardo Degennaro
- Department of Pharmacy-Drug Sciences, University of Bari "A. Moro" , Via Edoardo Orabona 4, Bari 70125, Italy
| | | | | |
Collapse
|
18
|
Boultwood T, Bull JA. Stereospecific Functionalization of Iodoaziridines via Unstabilized Aziridinyllithiums Generated by Iodine–Lithium Exchange. Org Lett 2014; 16:2740-3. [DOI: 10.1021/ol501024y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Tom Boultwood
- Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ, U.K
| | - James A. Bull
- Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ, U.K
| |
Collapse
|
19
|
Knochel P, M. Barl N, Werner V, Sämann C. The Halogen/Magnesium-Exchange Using iPrMgCl·LiCl and Related Exchange Reagents. HETEROCYCLES 2014. [DOI: 10.3987/rev-13-sr(s)4] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
20
|
Boultwood T, Affron DP, Trowbridge AD, Bull JA. Synthesis of cis-C-iodo-N-tosyl-aziridines using diiodomethyllithium: reaction optimization, product scope and stability, and a protocol for selection of stationary phase for chromatography. J Org Chem 2013; 78:6632-47. [PMID: 23738857 PMCID: PMC3805312 DOI: 10.1021/jo400956x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Indexed: 11/29/2022]
Abstract
The preparation of C-iodo-N-Ts-aziridines with excellent cis-diastereoselectivity has been achieved in high yields by the addition of diiodomethyllithium to N-tosylimines and N-tosylimine-HSO2Tol adducts. This addition-cyclization protocol successfully provided a wide range of cis-iodoaziridines, including the first examples of alkyl-substituted iodoaziridines, with the reaction tolerating both aryl imines and alkyl imines. An ortho-chlorophenyl imine afforded a β-amino gem-diiodide under the optimized reaction conditions due to a postulated coordinated intermediate preventing cyclization. An effective protocol to assess the stability of the sensitive iodoaziridine functional group to chromatography was also developed. As a result of the judicious choice of stationary phase, the iodoaziridines could be purified by column chromatography; the use of deactivated basic alumina (activity IV) afforded high yield and purity. Rearrangements of electron-rich aryl-iodoaziridines have been promoted, selectively affording either novel α-iodo-N-Ts-imines or α-iodo-aldehydes in high yield.
Collapse
Affiliation(s)
- Tom Boultwood
- Department of Chemistry, Imperial College
London, South Kensington, London SW7 2AZ, United Kingdom
| | - Dominic P. Affron
- Department of Chemistry, Imperial College
London, South Kensington, London SW7 2AZ, United Kingdom
| | - Aaron D. Trowbridge
- Department of Chemistry, Imperial College
London, South Kensington, London SW7 2AZ, United Kingdom
| | - James A. Bull
- Department of Chemistry, Imperial College
London, South Kensington, London SW7 2AZ, United Kingdom
| |
Collapse
|
21
|
Rayner PJ, O'Brien P, Horan RAJ. Preparation and reactions of enantiomerically pure α-functionalized Grignard reagents. J Am Chem Soc 2013; 135:8071-7. [PMID: 23647498 DOI: 10.1021/ja4033956] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A strategy for the generation of enantiomerically pure α-functionalized chiral Grignard reagents is presented. The approach involves the synthesis of α-alkoxy and α-amino sulfoxides in ≥99:1 dr and ≥99:1 er via asymmetric deprotonation (s-BuLi/chiral diamine) and trapping with Andersen's sulfinate (menthol derived). Subsequent sulfoxide → Mg exchange (room temperature, 1 min) and electrophilic trapping delivers a range of enantiomerically pure α-alkoxy and α-amino substituted products. Using this approach, either enantiomer of products can be accessed in 99:1 er from asymmetric deprotonation protocols without the use of (-)-sparteine as the chiral ligand. Two additional discoveries are noteworthy: (i) for the deprotonation and trapping with Andersen's sulfinate, there is a lack of stereospecificity at sulfur due to attack of a lithiated intermediate onto the α-alkoxy and α-amino sulfoxides as they form, and (ii) the α-alkoxy-substituted Grignard reagent is configurationally stable at room temperature for 30 min.
Collapse
Affiliation(s)
- Peter J Rayner
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | | | | |
Collapse
|
22
|
Abstract
An aziridinyl stannatrane 8 couples with aryl or alkenyl halides RX under modified Stille conditions to afford substituted aziridines. Efficient coupling at room temperature is possible in the best examples in the presence of ((t)Bu3P)2Pd and CuOP(O)Ph2 (CuDPP).
Collapse
Affiliation(s)
- Naresh Theddu
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
| | | |
Collapse
|