Regioselective catalytic addition of proton-donor reagents to esters of 1-alkylcyclopropene-3-carboxylic acids

Autor: Shapiro, E. A., Protopopova, M. N., Nefedov, O. M.
Zdroj: Russian Chemical Bulletin; April 1988, Vol. 37 Issue: 4 p683-688, 6p
Abstrakt: Conclusions 1.It has been observed for the first time that methyl 1-alkylcyclopropene-3-carboxy-lates in the presence of 5–10 mole % of CuCl or the complex CuCl·2MeC=CSiMe3 add hydrogen halides (HCl and HBr) and carboxylic acids with pKa values of 3–7 (monochloracetic, formic, acrylic, acetic, and permethrinic) at the C2-C3 bond with opening of the three-carbon ring to give 60–95% of the corresponding methyl E, Z-4-substituted-3-alkylbuten-3-oates in which the E-isomer predominates.2.Hydrofluoric and carboxylic acids with pKa values < 3 (trifluoro-, trichloro-, and dichloroacetic acids), in the presence of 5–10 mole % of CuCl·2MeC·CSiMe3 and atmospheric moisture convert methyl l-alkylcyclopropene-3-carboxylates into the corresponding 4-alkyl-5H-furan-2-ones (yields 80–90%), no products of the additive cleavage of the three-carbon ring being present.
Databáze: Supplemental Index
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