2-alkynoic acid carbon dioxide

Comparable to the dienes (see Figure 14) also alkynes may react with carbon dioxide yielding both chain or cyclic products. As shown in Figure 30 a 1 1 reaction should result alkynoic acids or substituted pyrones. As a further possibility Figure 30 shows the hypothetical combination of acetylene and two moles of carbon dioxide giving alky-nedioic acids or pyronic acids. Once again the reactions will be considered according to the transition metal applied. 

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