2-Methylbenzaldehyddialkylacetale der allgemeinen Formel I
in der die Substituenten folgende Bedeutung haben.
R¹C₃- bis C₂₀-Alkyl oder C₁- bis C₁₂-Alkoxy und
R²C₁- bis C₈-Alkyl,
mit der Maßgabe, daß R¹ nicht für Methoxy steht, wenn R² für Methyl steht, sowie deren Herstellung und deren Verwendung zur Herstellung von 2-Methylbenzaldehyden.
An object of the present invention is to provide a method for producing 2,4-dialkylbenzaldehyde with excellent conversion rate and yield, and excellent regioselectivity for formylation, by allowing carbon monoxide to react on a starting material containing a specific m-dialkylbenzene in the presence of hydrogen fluoride and boron trifluoride. The method for producing 2,4-dialkylbenzaldehyde according to the present invention comprises a step of allowing carbon monoxide to react on a starting material containing m-dialkylbenzene represented by formula (1) in the presence of hydrogen fluoride and boron trifluoride for formylation at least at a position (a), wherein the starting material is a dialkylbenzene containing more than 90 mol % of m-dialkylbenzene represented by formula (1), and the number of moles of boron trifluoride relative to 1 mole of m-dialkylbenzene represented by formula (1) is 0.7 mol or more and 3.0 mol or less:
a wherein R
1
represents an alkyl group having 1 or more and 3 or less carbon atoms, and R
2
represents a chain or cyclic alkyl group having 2 or more and 7 or less carbon atoms, with a secondary or tertiary carbon at the benzylic position, provided that the number of carbons of R
2
is larger than the number of carbons of R
1
.
A Practical, efficient, and atom economic alternative to the Wittig and Horner–Wadsworth–Emmons reactions for the synthesis of (E)-α,β-unsaturated esters from aldehydes
作者:Benjamin List、Arno Doehring、Maria T. Hechavarria Fonseca、Andreas Job、Ramon Rios Torres
DOI:10.1016/j.tet.2005.09.081
日期:2006.1
efficient new methodology for the synthesis of (E)-α,β-unsaturatedestersfromaldehydes. In our DMAP-catalyzed reaction, both aromatic as well as aliphatic aldehydes furnish the desired products highly regio- and stereoselectively if treated with commercially available or synthetically easily accessible malonic acid half ester. A large scale application in the synthesis of p-methoxycinnamates, which are