Catalytic one-pot synthesis of [5.5.5.6]fenestrane systems via a dicobalt octacarbonyl-catalyzed tandem cycloaddition of dienediynes.
Catalytic one-pot synthesis of fenestrane derivatives from dienediynes was developed: fenestranes were synthesized in high yields by a dicobalt octacarbonyl-catalyzed tandem cycloaddition of dienediynes.
Synthesis of [4.4.5.5]fenestrane
Abstract Intramolecular photochemical [2 + 2] cyclization of 3b gives 4b regio- and stereospecifically, along with fragmentation product 12b. The Cl atom of 4b was removed by ketalization, Li-NH3 reduction, and reoxidation with RuO4 to furnish 17b. The derived diazoketone 17d on treatment with rhodium(II) acetate underwent cyclization to the [4.4.5.5] fenestrane keto ketal 15. Subsequent reductions gave monoketone 23 and ultimately the parent hydrocarbon 6.
Thermal promotion of the cobalt catalyzed intramolecular Pauson-Khand reaction — An alternative experimental protocol for cyclopentenone synthesis
Abstract Heat alone has been found sufficient to promote intramolecular Pauson-Khand cyclizations catalyzed by high purity Co 2 (CO) 8 . The existence of a very narrow thermal window (e.g., 60 °C – 70 °C) for the attainment of efficient catalysis is a noteworthy characteristic of this process.