Vladimír Král

The first general synthetic approach to aikylidenemalonaldehydes

Abstract Alkylidenemalonaldehydes, hitherto assumed to be only unstable intermediates of some procedures, have now been made accessible by the reaction of dimethylaminomethylenemalonaldehyde with organometallic compounds.

Arylmethylenemalonaldehydes and their heterocyclic analogues: A novel group of organic lewis acids

Abstract The first general synthesis of arylmethylenemalonaldehydes and their heterocyclic analogues has been developed; some physico-chemical properties and reactions of these compounds are briefly mentioned.

An NMR and theoretical study on the conformational behaviour of benzylidenemalonaldehydes : A conformationally flexible unsaturated system

Abstract The conformational behaviour of the methylenemalonaldehyde fragment of the title compounds is characterized by solvent and temperture dependencies of 1J( CH O), 3J( C HO,C H O), 3J( C HO,C H ), 4J(C H O,C H O) and 4J(C H O,C H ) spin-spin couplings as well some ab initio (STO-3G) and semiempirical level Molecular orbital calculations. The conformational behaviour of the couplings is also discussed on the basis of some INDO/FPT calculations. The conformations of the two formyls are strongly correlated, the trans - cis arrangements being favored. The conformation of the Z-formyl is determined by the steric interaction with the aromatic nucleus. The conformations of the formyls are sensitive to solvent and substitution on the aryl. Approximate populations and couplings of the sites are derived. There is some evidence about the non-planarity of the methylenmalonaldehyde fragnent. Complex formation with Mg(C104)2 is reported.

A proof for negative vicinal proton-proton and proton-carbon spin-spin couplings in aliphatic aldehydes by using temperature and solvent dependence. Conformational studies on glycolaldehyde and di-tert-butyl ethanal

Abstract A negative 1 H, 1 H three-bond coupling 3 J ( CHO ), H ) was found for glycolaldehyde by varying solvent composition. A negative 3 J ( CHO ), C ) is demonstrated for di- tert -butyl ethanal by following the temperature dependence of the coupling. 3 J g B ( CHO ), H ) of −0.73 and 3 J g ( CHO ), C ) of −0.26 Hz (g = gauche ) for the compounds were estimated by fitting the temperature dependence of the couplings by using the two-site approach. The conformational behavior of the vicinal couplings in aliphatic aldehydes and the conformations of the title compounds are briefly discussed.