Bifuran diones

In both cases dicarbonylation of the alkyne triple bond occurs with reduction of one of the resulting carbonyl groups (2-propanol as hydrogen source). General surveys of carbocarbony-lation reactions of this type (also leading to bifuran diones) are available -2. Similar reaction types are observed in multicomponent carbonylative cyclizations (see Section 1.5.8.3.7.). 

An intramolecular double Friedel—Crafts acylation strategy in approaching different types of novel fused 2,2 -bifuran diones was explored (140CF391). 

Diketone anions of 1-aryl-4,4,4-trifluorobutane-l,3-dione (85) undergo nucleophilic addition of sodium acetylide to give tertiary 1,4-alkynediols (86). Double cyclization gives a 2,2 -bifuran. While the mechanism of acetylide addition has not been proved, a likely first step is the formal reaction of two carbanions to give a C-C bond. °... 

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