- Synthesis of 1-bromo-3-butyn-2-one and 1,3-dibromo-3-buten-2-one
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Synthetic procedures for the preparation of 1-bromo-3-butyn-2-one and 1,3-dibromo-3-buten-2-one are given. These compounds are prepared from 2-bromomethyl-2-vinyl-1,3-dioxolane, which can readily be prepared from 2-ethyl- 2-methyl-1,3-dioxolane. The synthetic routes are as follows: 2-bromomethyl-2-vinyl-1,3-dioxolane is converted to2-(1,2-dibromoethyl)-2- bromomethyl-1,3-dioxolane. Double dehydrobromination with tBuOK affords 2-ethynyl-2-bromomethyl-1,3-dioxolane. Formolysis with formic acid gives 1-bromo-3-butyn-2-one. Deacetalized 2-bromoethyl-2-vinyl-1,3-dioxolane was treated with Br2 and Li2CO3/12-crown-4 in tetrahydrofuran to give 1,3-dibrom-3-buten-2-one in moderate yield.
- Mekonnen, Alemayehu,Westerlund, Andreas,Havelkova, Martina,Descomps, Alexandre,Carlson, Rolf
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- Improved synthesis of 1-bromo-3-buten-2-one
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A convenient procedure for the synthesis of 1-bromo-3-buten-2-one, 4, from commercially available 2-ethyl-2-methyl-1,3-dioxolane, 1, is described. The procedure involves three reaction steps: (1) The acetal 1 is converted to 2-(1-bromoethyl)- 2-bromomethyl-1,3-dioxolane, 2, by reacting 1 with elemental bromine in dichloromethane to yield 98% of 2. (2) Dehydrobromination of 2 with potassium tert-butoxide in tetrahydrofuran gives 2-bromomethyl-2-vinyl-1,3- dioxolane, 3, in 84-93% yield. (3) Removal of the acetal protection from 3 by formolysis for 6-10 h afforded 1-bromo-3-buten-2-one, 4, in 85-94% yield. A more rapid method is acid hydrolysis of 3 under microwave activation (100°C, 8-10 min), by which 4 was obtained in 75% yield. Full experimental details are given. Taylor & Francis Group, LLC.
- Carlson, Rolf,Descomps, Alexandre,Mekonnen, Alemayehu,Westerlund, Andreas,Havelkova, Martina
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- Diversity-Orientated Stereoselective Synthesis through Pd-Catalyzed Switchable Decarboxylative C?N/C?S Bond Formation in Allylic Surrogates
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Switchable catalytic transformation of reactants can be a powerful approach towards diversity-orientated synthesis from easily available molecular synthons. Herein, an endogenous ligand-controlled, Pd-catalyzed allylic substitution allowing for either selective C?N or C?S bond formation using vinylethylene carbonates (VECs) and N-sulfonylhydrazones as coupling partners has been developed. This versatile methodology provides a facile, divergent route for the highly chemo- and stereoselective synthesis of functional allylic sulfones or sulfonohydrazides. The newly developed protocol features wide substrate scope (nearly 80 examples), broad functional group tolerance, and potential for the late-stage functionalization of bioactive compounds. The isolation and crystallographic analysis of a catalytically competent π-allyl Pd complex suggests that the pathway leading to the allylic products proceeds through a different manifold as previously proposed for the functionalization of VECs with nucleophiles.
- Deng, Lei,Kleij, Arjan W.,Yang, Weibo
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supporting information
p. 19156 - 19161
(2018/11/30)
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- 2-ACETYLNAPHTHO[2,3-B]FURAN -4,9-DIONE FOR USE ON TREATING CANCER
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The invention provides naphthofuran compounds, polymorphs of naphthofuran compounds, naphthofuran compounds in particle form, purified compositions that contain one or more naphthofuran compounds, purified compositions that contain one or more naphthofuran compounds in particle form, and methods of using these naphthofuran compounds, polymorphs, purified compositions and/or particle forms to treat subjects in need thereof.
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Paragraph 0292; 0293
(2016/02/20)
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- Deprotection of acetals from unsaturated, unstable bromoketones
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The unstable ketones 1-bromo-3-buten-2-one, 1-bromo-3-butyn-2-one, and 1,3-dibromo-3-buten-2-one can be obtained from the corresponding acetals in high yields by treating the acetals with anhydrous iron (III) chloride suspended on dry silica. A simplified procedure for preparing the reagent is also given.
- Descomps, Alexandre,Carlson, Rolf
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p. 757 - 761
(2014/03/21)
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- Synthesis of 1-bromo-3-buten-2-one
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A synthetic method for 1-bromo-3-buten-2-one is given. The compound is prepared through the following sequence: 2-butanone to 2-methyl-2-ethyl-1,3- dioxolane to 2-(1-bromoethyl)-2-bromomethyl-1,3-dioxolane to 2-bromomethyl-2- vinyl-1,3-dioxolane to the final product. Full experimental details including spectral data are given.
- Westerlund, Andreas,Carlson, Rolf
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p. 4035 - 4042
(2007/10/03)
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