A new approach to 2,2-disubstituted 1-(methylsulfanyl)vinyl phosphonates via an intermediate thiocarbonyl ylide |
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Authors: | Grzegorz Mlostoń Katarzyna Urbaniak Heinz Heimgartner |
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Institution: | a Department of Organic and Applied Chemistry, University of ?ód?, Narutowicza 68, PL-90-136 ?ód?, Poland b Institute of Organic Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland |
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Abstract: | The reaction of methyl (diethylphosphoryl)dithioformate (6) with diaryldiazomethanes 7a-d in THF at −60 °C to room temperature followed by desulfurization is shown to be a convenient method for the preparation of 2,2-disubstituted 1-(methylsulfanyl)vinyl phosphonates 8a-d. The analogous reactions with 2-diazoacenaphthen-1-one (7f) or 2-diazocamphor (7g) in refluxing THF yield selectively the corresponding (Z)- and (E)-vinyl phosphonates 8f and 8g, respectively. These products can be easily oxidized to the vinylsulfoxides 13 and vinylsulfones 14. On the other hand, methyl (diethylphosphoryl)dithioformate (6) and 2-diazo-1,2-diphenylethanone (7e) in boiling THF react to give the 1,3-oxathiole 12. All these reactions occur via an intermediate thiocarbonyl ylide 11 followed by 1,3-dipolar electrocyclization and sulfur extrusion or 1,5-dipolar electrocyclization. |
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