Formation from alkynes

E)-Alkenes. The scope was defined for the formation from alkynes by reduction with Li/NHj. 

Scheme 4.12 Ketene formation from alkyne oxidation with a ruthenium catalyst.

The few examples of catalytic cyclopentenone formation from alkyne, alkene, and CO are discussed below, as is the bifuryli-denedione synthesis from alkyne and CO. It should also be noted that Co4(CO)i2, obtained by heating the dinuclear carbonyl, can probably replace the latter in most of the above catalytic reactions, but without obvious advantage. 

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