1
|
Catalyst-Free Formal Conjugate Addition/Aldol or Mannich Multicomponent Reactions of Mixed Aliphatic Organozinc Reagents, π-Electrophiles and Michael Acceptors. Molecules 2023; 28:molecules28031401. [PMID: 36771065 PMCID: PMC9919058 DOI: 10.3390/molecules28031401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/19/2023] [Accepted: 01/27/2023] [Indexed: 02/05/2023] Open
Abstract
Catalyst-free multicomponent reactions of mixed alkylzinc reagents with Michael acceptors and aldehydes, ketones or activated imines are described. Primary, secondary and tertiary alkylzinc reagents, pre-generated in acetonitrile from the corresponding iodoalkanes, were used in the process, leading to the very efficient formation of a variety of β-hydroxycarbonyl compounds. The imines showed more contrasting results, due to the direct addition of the organozinc compound to the C=N bond. Mechanistic assays involving TEMPO account for a polar instead of a radical character of the reaction.
Collapse
|
2
|
Stabilized Arylzinc Iodides in Negishi Acylative Cross-Coupling: A Modular Synthesis of Chalcones. ORGANICS 2022. [DOI: 10.3390/org3020006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Stabilized arylzinc iodides, synthesized by direct insertion of zinc into the corresponding halides, were used as nucleophiles into an acylative Negishi coupling reaction to synthesize chalcones. The reaction conditions were optimized to afford optimal results on a model reaction and then applied to synthesize nine compounds. Esters, chlorides, electron-rich, electron-poor and sterically hindered substrates are well tolerated and even heteroaryl derivatives can be synthesized.
Collapse
|
4
|
Casotti G, Rositano V, Iuliano A. Enantioselective Conjugate Addition of Stabilized Arylzinc Iodide to Enones: an Improved Protocol of the Hayashi Reaction. Adv Synth Catal 2020. [DOI: 10.1002/adsc.202001141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Gianluca Casotti
- Dipartimento di Chimica e Chimica Industriale Università di Pisa Via Giuseppe Moruzzi, 13 56124 Pisa Italy Phone
| | - Vincenzo Rositano
- Dipartimento di Chimica e Chimica Industriale Università di Pisa Via Giuseppe Moruzzi, 13 56124 Pisa Italy Phone
| | - Anna Iuliano
- Dipartimento di Chimica e Chimica Industriale Università di Pisa Via Giuseppe Moruzzi, 13 56124 Pisa Italy Phone
| |
Collapse
|
5
|
Dell'Aera M, Perna FM, Vitale P, Altomare A, Palmieri A, Maddock LCH, Bole LJ, Kennedy AR, Hevia E, Capriati V. Boosting Conjugate Addition to Nitroolefins Using Lithium Tetraorganozincates: Synthetic Strategies and Structural Insights. Chemistry 2020; 26:8742-8748. [PMID: 32181938 DOI: 10.1002/chem.202001294] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Indexed: 11/09/2022]
Abstract
We report the first transition metal catalyst- and ligand-free conjugate addition of lithium tetraorganozincates (R4 ZnLi2 ) to nitroolefins. Displaying enhanced nucleophilicity combined with unique chemoselectivity and functional group tolerance, homoleptic aliphatic and aromatic R4 ZnLi2 provide access to valuable nitroalkanes in up to 98 % yield under mild conditions (0 °C) and short reaction time (30 min). This is particularly remarkable when employing β-nitroacrylates and β-nitroenones, where despite the presence of other electrophilic groups, selective 1,4 addition to the C=C is preferred. Structural and spectroscopic studies confirmed the formation of tetraorganozincate species in solution, the nature of which has been a long debated issue, and allowed to unveil the key role played by donor additives on the aggregation and structure of these reagents. Thus, while chelating N,N,N',N'-tetramethylethylenediamine (TMEDA) and (R,R)-N,N,N',N'-tetramethyl-1,2-diaminocyclohexane (TMCDA) favour the formation of contacted-ion pair zincates, macrocyclic Lewis donor 12-crown-4 triggers an immediate disproportionation process of Et4 ZnLi2 into equimolar amounts of solvent-separated Et3 ZnLi and EtLi.
Collapse
Affiliation(s)
- Marzia Dell'Aera
- Dipartimento di Farmacia-Scienze del Farmaco, Università di Bari "A. Moro", Consorzio C.I.N.M.P.I.S., Via E. Orabona 4, 70125, Bari, Italy.,Istituto di Cristallografia (IC-CNR), Via Amendola 122/o, 70125, Bari, Italy
| | - Filippo Maria Perna
- Dipartimento di Farmacia-Scienze del Farmaco, Università di Bari "A. Moro", Consorzio C.I.N.M.P.I.S., Via E. Orabona 4, 70125, Bari, Italy
| | - Paola Vitale
- Dipartimento di Farmacia-Scienze del Farmaco, Università di Bari "A. Moro", Consorzio C.I.N.M.P.I.S., Via E. Orabona 4, 70125, Bari, Italy
| | - Angela Altomare
- Istituto di Cristallografia (IC-CNR), Via Amendola 122/o, 70125, Bari, Italy
| | - Alessandro Palmieri
- School of Science and Technology, Chemistry Division, University of Camerino, Via S. Agostino 1, 62032, Camerino, Italy
| | - Lewis C H Maddock
- Department of Pure and Applied Chemistry, University of Strathclyde Glasgow, G1 1XL, Glasgow, UK
| | - Leonie J Bole
- Department für Chemie und Biochemie, Universität Bern, 3012, Bern, Switzerland
| | - Alan R Kennedy
- Department of Pure and Applied Chemistry, University of Strathclyde Glasgow, G1 1XL, Glasgow, UK
| | - Eva Hevia
- Department für Chemie und Biochemie, Universität Bern, 3012, Bern, Switzerland
| | - Vito Capriati
- Dipartimento di Farmacia-Scienze del Farmaco, Università di Bari "A. Moro", Consorzio C.I.N.M.P.I.S., Via E. Orabona 4, 70125, Bari, Italy.,Dipartimento di Chimica, Istituto di Chimica dei Composti Organometallici (ICCOM)-CNR, Università di Bari "A. Moro", Via E. Orabona 4, 70125, Bari, Italy
| |
Collapse
|