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Synthesis 1995; 1995(4): 392-396
DOI: 10.1055/s-1995-3914
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Free Radical Reaction of α-Haloalkylphosphonates with Alkenes and Alkynes: A New Approach to Modified Phosphonates

Piotr Bałczewski, Marian Mikołajczyk*
  • *Center of Molecular and Macromolecular Studies, Polish Academy of Sciences, Department of Organic Sulfur Compounds, 90-363 Łodź, Sienkiewicza PL-112, Poland, Fax +48(42)847126
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Publication Date:
31 December 2000 (online)

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A new approach to the synthesis of phosphonates 3 functionalized in the α- and γ-phosphonate positions by alkyl, ethoxy, butoxy, acetoxy, acetyl and cyanide groups and allylphosphonate 6 is described. It is based on the radical reaction of α-halosubstituted phosphonates 1 (X=Cl, Br, I) with the terminally unsubstituted alkenes 2 (1-heptene, ethoxyethene, butoxyethene, acetoxyethene, acrylonitrile, methyl vinyl ketone) and alkyne 5 (hept-1-yne). The reaction involving the tin hydride method (Bu3SnH(AlBN) was more effective with alkenes than with alkynes (40-72% versus 20-30%). With electron-rich alkenes, chloro- and bromomethylphosphonates 1 (X=Cl, Br) gave higher yields than iodomethylphosphonate 1 (X=I). Diethyl methylphosphonate 4, as a reduction product of 1, accompanied 3 and 6 in the above reactions. The yield of 4 could be reduced by optimizing the reaction conditions.

diethyl α-haloalkylphosphonates - alkene - alkyne - free radical reaction - tributyltin hydride - α,α’-azaisobutyronitrile

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