Diazoalkanes. Part I. Reaction of Diazomethane with Methyl Ether of Cyclic Hydroxy methyleneketones

Methyl ethers of cyclic α-hydroxymethyleneketones ( $\beta$-oxoaldehydes) have been found to react with diazomethane leading to $△$¹-pyrazolines which readily undergo elimination of nitrogen to afford $\beta$-methylated products. The latter on hydrolysis furnish α-acetylketones and it thus constitutes a simple method for the preparation of α-acetylketones from the readily accessible $\beta$-oxo-aldehydes. A convenient preparation of methyl ether of hydroxymethyIeneketones and their probable configuration have also been described. A preliminary account has already been published.