Abstract A synthetic route for obtaining 1‐butoxy‐1,3,3‐triethoxy[1,3‐ 2 H 2 ]propane a stable diacetal of the malondialdehyde, is described. The synthesis involves the condensation of deuterated butylvinyl ether with deuterated triethyl orthoformate in the presence of montmorillonite clay K‐10. The deuteration of butyl vinyl ether was accomplished via the intermediary formation of a stannane derivative which was quantitatively metallated by n ‐butyllithium and then treated with 2 H 2 O. From the diacetal the 1,3‐dideuterated malondialdehyde was obtained by a short treatment with acid ion exchange resin.
Beckmann rearrangement of Δ4-6-hydroxyimino steroids gave solely the products of vinyl migration. Compounds having a 3-hydroxy or 3-acetoxy group suffer elimination of the substituent during the reaction.
The so-called “sialo-chemical-biology” has become an attractive research area, as an increasing number of natural products containing a sialic acid moiety have been shown to play important roles in biological, pathological, and immunological processes. The intramolecular lactones of sialic acids are a subclass from this crucial family that could have central functions in the discrimination of physiological and pathological conditions. In this review, we report an in-depth analysis of the synthetic achievements in the preparation of the intramolecular lactones of sialic acids (1,4-, 1,7- and γ-lactones), in their free and/or protected form. In particular, recent advances in the synthesis of the 1,7-lactones have allowed the preparation of key sialic acid derivatives. These compounds could be used as authentic reference standards for their correct determination in biological samples, thus overcoming some of the limitations of the previous analytical procedures.
