Multiple unsaturated compounds and process for the preparation thereof

摘要

The invention comprises ethers of formula where R1 is a C1- 6 alkyl group and the alkynyl acetals from which they are prepared of formula wherein R1 is as above and R2 is hydrogen, or an alkyl, aryl, or heterocyclic group or a group of formula where R3, R5 and R6 are hydrogen or C1- 6 alkyl groups and R4 is a C1- 6 alkyl group. Compounds (1) are prepared by reacting compounds (II) with a strong base, suitably an alkali metal amide in liquid ammonia. The alkynyl acetals of Formula (II) are prepared by coupling propyne with 1,1-dialkoxy-3 ketobutane using a Grignard or Nef reaction and converting the resulting metal compound of 1,1-dialkoxy-3hydroxy - 3 - methyl - hex - 4 - yne, into an ether. The alkynyl acetals containing the group (III) are prepared by reacting 1,1-dialkoxy-3hydroxy - 3 - methyl - hex - 4 - yne with a vinyl ether of formula where R3, R4, R5, R6 have the same meaning as above. This reaction may take place in the presence of an acid, for example, or in the presence of an indifferent solvent. Among the compounds prepared are 1,1-dimethoxy-3-tetrahydropyranyloxy - 3 - methyl - hex - 4 - yne, 1,1 - diethoxy - 3 - tetrahydropyranyloxy - 3 methyl - hex - 4 - yne, 1 - methoxy - 3 - methylhexa - 1,3 - diene - 5 - yne, 1 - ethoxy - 3-methylhexa - 1,3 - diene - 5 - yne, 1 - n - butoxy - 3 methyl - hexa - 1,3 - diene - 5 - yne.