The Smallest Vicinal Tricarbonyl Compound as a Monohydrate and Tetracarbonyl Compound as a Thiane Derivative – First Effective Synthesis, Characterization and Chemistry

An effective synthesis of 2‐oxo‐1,3‐propanedial monohydrate or mesoxaldehyde ( 6a ) and the first synthesis of 2,3‐dioxo‐1,4‐butanedial ( 18 ) as a thiane derivative are reported. These first members of the smallest vicinal tri‐ and tetracarbonyl compounds are stabilized by conversion to thiane derivatives 8 , 9 , 10 , 11 , 12 , 15 and 19 , which can be isolated as long‐lived compounds at room temperature. The structures of these novel thianes 8 , 10 , 12 and 15 were confirmed by their X‐ray crystal structures. The synthesis of a series of protected as well as free heterocyclic aldehydes (pterins and quinoxalines) by the use of the appropriate tricarbonyl compounds is also reported. Additionally, a one‐step synthetic strategy to prepare a series of different biheterocycles with the smallest vicinal tetracarbonyl compound is demonstrated.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)