Regioselectivity in the C-alkylation of triethyl 3-methyl-4-phosphonobut-2-enoate |
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Authors: | G V Kryshtal' G M Zhdankina E P Serebryakov |
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Institution: | (1) N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 117913 Moscow, Russian Federation |
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Abstract: | The reaction of triethyl 3-methyl-4-phosphonobut-2-enoate (1) with three alkyl halides AlkX (Alk=Pri, Me2CHCH2CH2, andc-C5H9; X=Br, I) in the system KOH(solid)∩DMF∩Bun
4NBr at ≈20°C gives exclusively products of alkylation at C(2) with Δ2 and/or Δ3 position of the double bond. Under the same conditions, the reaction of 1 with MeI gives a mixture of products with different
substitution patterns. Only the use of an ion pair extraction technique affords 2-methyl-Δ2-products selectively, albeit in rather moderate yields. The Horner—Emmons olefination of PhCHO with the resulting phosphonates
gives ethyl 2-alkyl-3-methyl-5-phenylpenta-2,4-dienoates in high yields.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1839–1844, October, 1997. |
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Keywords: | triethyl 3-methyl-4-phosphonobut-2-enoate alkylation phase transfer catalysis Horner— Emmons reaction regioselectivity |
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