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Templ J, Gjata E, Getzner F, Schnürch M. Monoselective N-Methylation of Amides, Indoles, and Related Structures Using Quaternary Ammonium Salts as Solid Methylating Agents. Org Lett 2022; 24:7315-7319. [PMID: 36190781 PMCID: PMC9578047 DOI: 10.1021/acs.orglett.2c02766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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We herein report the use of phenyl trimethylammonium
iodide (PhMe3NI) as a safe, nontoxic, and easy-to-handle
reagent for an
absolutely monoselective N-methylation of amides and related compounds
as well as for the N-methylation of indoles. In addition, we expanded
the method to N-ethylation using PhEt3NI. The ease of operational
setup, high yields of ≤99%, high functional group tolerance,
and especially the excellent monoselectivity for amides make this
method attractive for late-stage methylation of bioactive compounds.
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Affiliation(s)
- Johanna Templ
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163, 1060 Wien, Austria
| | - Edma Gjata
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163, 1060 Wien, Austria
| | - Filippa Getzner
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163, 1060 Wien, Austria
| | - Michael Schnürch
- Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163, 1060 Wien, Austria
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Xu XH, Hao EJ, Shi Z, Dong ZB. Easy S-Alkylation of Arylthioureas and 2-Mercaptobenzothiazoles Using Tetraalkylammonium Salts under Transition-Metal-Free Conditions. J Org Chem 2022; 87:9675-9687. [PMID: 35896442 DOI: 10.1021/acs.joc.2c00728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A highly-efficient and practical method for S-alkylation of arylthioureas was reported. Using tetraalkylammonium salts as alkylation reagents, a series of 68 S-substituted aryl-isothioureas were obtained in good to excellent yields under transition-metal-free conditions. The protocol features simple performance, broad functional group tolerance, good to excellent yields, and easily available starting materials, showing potential synthetic value for the preparation of diverse biologically or pharmaceutically active compounds.
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Affiliation(s)
- Xiao-Hu Xu
- School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Wuhan 430205, China
| | - Er-Jun Hao
- School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang 453007, China
| | - Zhen Shi
- Hubei Key Laboratory of Biologic Resources Protection and Utilization, Hubei Minzu University, Enshi 445000, China
| | - Zhi-Bing Dong
- School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Wuhan 430205, China.,School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang 453007, China.,Key Laboratory of Green Chemical Process, Ministry of Education, Wuhan Institute of Technology, Wuhan 430205, China.,Engineering Research Center of Phosphorus Resources Development and Utilization, Ministry of Education, Wuhan Institute of Technology, Wuhan 430205, China.,Hubei Key Laboratory of Biologic Resources Protection and Utilization, Hubei Minzu University, Enshi 445000, China
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Cheng HG, Pu M, Kundu G, Schoenebeck F. Selective Methylation of Amides, N-Heterocycles, Thiols, and Alcohols with Tetramethylammonium Fluoride. Org Lett 2020; 22:331-334. [PMID: 31834810 DOI: 10.1021/acs.orglett.9b04400] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
We herein disclose the use of tetramethylammonium fluoride (TMAF) as a direct and selective methylating agent of a variety of amides, indoles, pyrroles, imidazoles, alcohols, and thiols. The method is characterized by operational simplicity, wide scope, and ease of purification. Our computational studies suggest a concerted methylation-deprotonation as the preferred reaction pathway.
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Affiliation(s)
- Hong-Gang Cheng
- Institute of Organic Chemistry , RWTH Aachen University , Landoltweg 1 , 52074 Aachen , Germany
| | - Maoping Pu
- Institute of Organic Chemistry , RWTH Aachen University , Landoltweg 1 , 52074 Aachen , Germany
| | - Gourab Kundu
- Institute of Organic Chemistry , RWTH Aachen University , Landoltweg 1 , 52074 Aachen , Germany
| | - Franziska Schoenebeck
- Institute of Organic Chemistry , RWTH Aachen University , Landoltweg 1 , 52074 Aachen , Germany
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Chen Y. Recent Advances in Methylation: A Guide for Selecting Methylation Reagents. Chemistry 2018; 25:3405-3439. [DOI: 10.1002/chem.201803642] [Citation(s) in RCA: 119] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Indexed: 11/10/2022]
Affiliation(s)
- Yantao Chen
- Medicinal Chemistry, Cardiovascular, Renal and Metabolism, IMED Biotech UnitAstraZeneca Gothenburg Sweden
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Chavan SP, Kadam AL, Lasonkar PB, Gonnade RG. Synthesis of 3-Azidopiperidine Skeleton Employing Ceric Ammonium Nitrate (CAN)-Mediated Regioselective Azidoalkoxylation of Enol Ether: Total Synthesis of D2 Receptor Agonist (±)-Quinagolide. Org Lett 2018; 20:7011-7014. [DOI: 10.1021/acs.orglett.8b02900] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Subhash P. Chavan
- Division of Organic Chemistry, CSIR-National Chemical Laboratory, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), New Delhi 110025, India
| | - Appasaheb L. Kadam
- Division of Organic Chemistry, CSIR-National Chemical Laboratory, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), New Delhi 110025, India
| | - Pradeep B. Lasonkar
- Division of Organic Chemistry, CSIR-National Chemical Laboratory, Pune 411008, India
| | - Rajesh G. Gonnade
- Academy of Scientific and Innovative Research (AcSIR), New Delhi 110025, India
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
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Hutchins RO, Natale NR. CYANOBOROHYDRIDE. UTILITY AND APPLICATIONS IN ORGANIC SYNTHESIS. A REVIEW. ORG PREP PROCED INT 2009. [DOI: 10.1080/00304947909354852] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Gribble GW, Nutaitis CF. SODIUM BOROHYDRIDE IN CARBOXYLIC ACID MEDIA. A REVIEW OF THE SYNTHETIC UTILITY OF ACYLOXYBOROHYDRIDES. ORG PREP PROCED INT 2009. [DOI: 10.1080/00304948509355522] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Sannigrahi M, Pinto P, Chan T, Shih NY, George Njoroge F. Novel synthesis of sterically hindered N-substituted lactams from imides. Tetrahedron Lett 2006. [DOI: 10.1016/j.tetlet.2006.05.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Drage JS, Earl RA, Vollhardt KPC. Deoxygenation of allylic carbinolamides and related alcohols by acidic sodium cyanoborohydride: Scope and limitations. J Heterocycl Chem 1982. [DOI: 10.1002/jhet.5570190358] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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