- Synthesis of 2-(1-Chloroalkyl)-1,3-benzodithioles and 2-Alkylidene-1,3-benzodithioles
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Boron trifluoride promoted transdithioaceatalization of α-chloroacetals with 1,2-benzodithiol affords good yileds of 2-(1-chloroalkyl)-1,3-benzodithioles, which dehydrochlorinates very satisfactorily to the corresponding 2-alkylidene-1,3-benzodithioles.
- Bellesia, Franco,Boni, Monica,Ghelfi, Franco,Pagnoni, Ugo M.
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p. 1721 - 1724
(2007/10/02)
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- General Methods for Synthesizing 2,4-Diacylpyrroles and their Precursors Containing One or Two Masked Acyl Groups
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A thorough study of the synthesis of 2,4-diacylpyrroles by direct acylation of pyrrole and 2- and 3-acylpyrroles is reported.Among these, Friedel-Crafts acylation of 3-acylpyrroles is the most general and advantageous method because it utilises easily accessible starting materials.In addition it is always regiospecific and readily provides 2,4-diacylpyrroles containing identical or different acyl groups in very high yields (81-100percent) under mild conditions, Alternative procedures concern the synthesis of precursors of 2,4-diacylpyrroles containing one or two acyl groups masked by a 1,3-benzodithiolyl or 1,3-benzoxathiolyl group and subsequent hydrolysis with HgO-35percent aq.HBF4-Me2SO.Overall yields are always good (52-60percent).Indirect acylation constitutes a secure complement to direct acylation when it is necessary to operate in the presence of protected acyl groups.
- Cadamuro, Silvano,Degani, Iacopo,Dughera, Stefano,Fochi, Rita,Gatti, Antonella,Piscopo, Laura
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p. 273 - 284
(2007/10/02)
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- 2-SUBSTITUTED 1,3-BENZODITHIOLIUM TETRAFLUOROBORATES AS USEFUL ACYLATING AGENTS OF PYRROLE
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A comparative study on the acylation of pyrrole by utilizing 2-substituted 1,3-benzodithiolium tetrafluoroborates instead of 2-substituted 1,3-benzoxathiolium tetrafluoroborates has been accomplished.The use of 2-substituted 1,3-benzodithiolium tetrafluoroborates proved to be more convenient since it gives higher yields of 2-acylpyrroles (58-90percent) and appears of larger applicability for the preparation of symmetrical and unsymmetrical 2,5-diacylpyrroles which were obtained in most cases in quantitative yields.
- Barbero, Margherita,Cadamuro, Silvano,Degani, Iacopo,Dughera, Stefano,Fochi, Rita,et al.
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p. 619 - 627
(2007/10/02)
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- A SIMPLE SYNTHESIS AND SOME CHEMICAL PROPERTIES OF BENZO-1,4-DITHIAFULVENES
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The synthesis of benzo-1,4-dithiafulvenes by a simple treatment of 2-substituted 1,3-benzodithiolium tetrafluoroborates - obtained starting from carboxylic acids or acyl chlorides and tetrafluoroboric acid/ ether complex - with acetonitrile water is reported.The reaction is very fast and affords the products in high over-all yields and under mild conditions.The reactions of benzo-1,4-dithiafulvenes with reducing agents (zinc/trifluoroacetic acid and acetonitrile, zinc/deuterated trifluoroacetic acid and acetonitrile, Raney nickel) and with oxidizing agents (hydrogen peroxide/ acetic acid, sodium hypochlorite, chlorine gas/water) are also reported.These reactions show the interesting synthetic potential of benzo-1,4-dithiafulvenes.
- Barbero, Margherita,Cadamuro, Silvano,Ceruti, Maurizio,Degani, Iacapo,Fochi, Rita,Regondi, Valeria
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p. 227 - 236
(2007/10/02)
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- A New Synthetic Application of 1,2-Benzodithiolium Cations: Synthesis of Aldehydes by 1-Carbon Homologation of Carbonyl Compounds
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Eleven aldehydes (6a-l) were synthesized by 1-carbon homologation of ketones and aldehydes according to the following sequence: Horner-Emmons reaction of 2-(O,O-dimethylphosphonyl)-1,3-benzodithiole (1) and various carbonyl compounds (2) to give benzo-1,4-dithiafulvenes (3); reduction with sodium borohydride and tetrafluoroboric acid-ether complex in dry acetonitrile to 1,3-benzodithioles (5); subsequent hydrolysis of these with mercury(II)oxide and aqueous tetrafluoroboric acid (35percent) in tetrahydrofuran.The procedure is simple, of wide application, and afforded pure aldehydes in good overall yields (55-88percent).
- Ceruti, Maurizio,Degani, Iacopo,Fochi, Rita
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