Ethynylation of polyunsaturated aldehydes and ketones

A catalytic ethynylation process which comprises conducting a catalytic ethinylation reaction of a compound of formula (I):

• wherein
• R1 signifies —H or —CH3,
• R2 signifies —H, and
• R3 signifies a moiety selected from the group consisting of:
• with ethyne in NH3 as a solvent and in the presence of a catalyst of formula ROH, wherein R signifies K or Cs at a catalytic ethinylation reaction temperature between −40° C. to 10° C.