Unsymmetric pyranopyrandiones

In the presence of acetylenes, the latter are incorporated into the products to give unsymmetric pyranopyrandiones (Eq. 11.46). 

Cyclopropenones and carbon monoxide react in the presence of Ru3(CO)12 to form tetrasubstituted pyranopyr-andiones 655 in high yield (Equation 266) <2002JA6824>. Unsymmetrical tetrasubstituted pyranopyrandiones 656 can be accessed by the cross-carbonylation of cyclopropenones and internal alkynes in the presence of a ruthenium catalyst (Equation 267) <2002JA6824>. 

The reaction was extended to the cross-carbonylation of cyclopropenones and internal alkynes, leading to unsymmetrically substituted pyranopyrandiones (Eq. 18) [33]. 

Treatment of dialkylcyclopropenones with catalytic amounts of Ru3(CO) 2 and EtgN under CO resulted in carbonylative dimerization of cyclopropenones to give pyranopyrandiones in good yields (Scheme 2.111) [169]. Cross-carbonylation of dipropylcyclopropenone with dec-5-yne resulted in unsymmetrically substituted pyranopyrandione 148. 

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