Synthesis of optically active chloro alkanoic esters
作者:Ugo Azzena、Giovanna Delogu、Giovanni Melloni、Oreste Piccolo
DOI:10.1016/s0040-4039(01)80743-7
日期:1989.1
The stereospecific synthesis (optical yield up to 94%) of opticallyactive (R)-alkyl-2-chloropropionate and (S)-alkyl-3-chlorobutanoate by the action of AlCl3 on the corresponding (S)-2-mesyloxy- and (R)-3-mesyloxy-derivatives is described.
Herein we report a new method for the catalytic Appel reaction by P(III)/P(V) redox cycling at very low catalyst loadings of 1–2 mol % using low amounts of hexachloroacetone as the halogen source and phenylsilane as the terminal reductant. Twenty-six alcohols and nine epoxides containing a wide variety of functional groups were converted to the respective chlorides and dichlorides in yields of up to
The alkylation of aromatic compounds, such as benzene, toluene, chlorobenzene, and naphthalene, with optically active (S)-alkyl 2-(sulfonyloxy)propionates and (R)-alkyl 3-(sulfonyloxy)butanoates in the presence of AlCl3 afforded optically active (S)-alkyl 2-arylpropionates and (S)-alkyl 3-arylbutanoates in fair to good chemical yields (40-84%) and in good to excellent optical yields (61-97%). As usually occurs in Friedel-Crafts alkylation reactions, poor regioselectivity was observed.