2-Propionyl-1,3-dioxans - prepd. in high yield by condensing butyne-1,4-diol with 1,3-diols, are useful as inters. for ethyl glyoxals

摘要

Title cpds. of formula (I): (in which R1-4 are opt. different short-chain alkyl gps. or H) are prepd. by a single-stage condensn. from butyn-1,4-diol and a 1,3-diol of formula HO-CHR1-CR2R3-CHR4-OH, the reaction proceeding very smoothly. Condensn. pref. is carried out in the presence of a (gp. I) metal salt, gen. at 100-200 (120-150) degrees C in the liq. phase and takes 10-240 mins. (I) can be hydrolysed to enol-acetates, alpha-unsatd. alpha-acyloxyaldehyde Me.CH:C (OAc).CHO, carbinols, natural substances, alpha-aminobutyraldehyde and 2-aminobutan-1-ol.