Unexpected formation of benzaldehydes by the reactions of dithioacetals derived from cinnamaldehydes with 2,3-dichloro-5,6-dicyano-<i>p</i>-benzoquinone in aqueous solvents
1,3-Dithianes 1, 1,3-dithiolanes 2, and diphenyldithioacetals 3 derivedfrom cinnamaldehydes reacted with 2,3-dichloro-5,6-dicyano-p-benzoquinone in aqueous solvents to give benzaldehydes 4. Hydride transfer from 1–3 to 2,3-dichloro-5,6-dicyano-p-benzoquinone followed by hydrolysis and oxidative carbon-carbon bond cleavage would produce benzaldehydes 4.
An effective method to synthesize α‐functionalized furan and pyrrole derivatives was developed using 2‐alkoxy‐2,3‐dihydrofurans as modular precursors. This protocol featured a previously unreported tandem nucleophilic substitution/heteroaromatization reaction. Nucleophiles such as indole, α‐oxoketene dithioacetal, trimethoxybenzene, and dimethoxynaphthalene can react readily with 2‐alkoxy‐2,3‐dihydrofurans
Infrared spectra and theoretical study of the conformations of substituted benzoylketene-S,S-acetals
作者:A. Perjéssy、W. -D. Rudorf、D. Loos、Z. Šusteková
DOI:10.1007/bf00811088
日期:1994.12
The C=O stretching frequencies of substituted benzoylketene-S,S-dimethylacetals (1a-1o) and benzoylketene-S,S-ethyleneacetals (2a-2m) were measured in CHCl3 and CCl4 and correlated with the Hammett substituent constants. The correlations were split into two different and well separated lines for compounds containing electron donor and electron acceptor substituents, which were assigned to s-trans and s-cis quasiplanar conformations. The correlations of carbonyl stretching frequencies with C=O bond orders and oxygen atom charge densities calculated using the semiempirical AM1 method reveal similar results consistent with assignments of structures 1 and 2 to two quasiplanar conformations. The preparation of some new benzoylketene-S,S-acetals is reported as well.