Structure of β-Acylacrylic Acids
IN previous publications1–5 the β-formyl-, β-acetyl- and β-pivaloyl-acrylic acids were investigated by means of their spectra in the ultra-violet and infra-red. This work has been extended to comprise the α-methyl-β-acrylic acid6,7. In regard to cis–trans isomerism and open or cyclic structure for the preparations used, the infra-red spectra (in the case of acid (5) also by means of the nuclear magnetic resonance) have confirmed the following structures : (1) β-Formylacrylic acid, m.p. 53–56° C.: cyclic, cis (2) β-Acetylacrylic acid, m.p. 122–125° C.: trans (probably with a smaller amount cis-open acid) (3) β-Pivaloylacrylic acid, m.p. 84–85° C.: cyclic, cis (4) β-Pivaloylacrylic acid, m.p. 94–95° C.: trans (5) α-Methyl-β-acetylacrylic acid, m.p. 98–101° C.: cyclic, cis
Photochemistry of β-Acylacrylic Acids and Their Esters
The irradiation of methyl trans-β-acetylacrylate (I-A) in methanol or acetone or without any solvent gave the cis-isomer (I-B). On the contrary, the irradiation of the free acid of I-A, trans-β-acetylacrylic acid (II-A), in methanol or without any solvent gave the angelica lactone, 5-methyl-5-hydroxy-2-oxo-2,5-dihydrofuran (II-C). The irradiation of trans-β-pivaloylacrylic acid (III-A) in methanol also afforded the angelica lactone, 5-t-butyl-5-hydroxy-2-oxo-2,5-dihydrofuran (III-C). The reaction route from a cis-isomer to an angelica lactone was explained in terms of the inductive effect.
Versuche zur Synthese von Steroiden, III. Mitteil.: Diensynthesen mit β‐Acetyl‐acrylsäure und α‐Methyl‐β‐äthyl‐acrolein
Als philodiene Komponente fur Synthesen nach Diels-Alder wird erstmals β-Acetyl-acrylsaure benutzt. Mit 2.3-Dimethyl- bzw. 1.4-Diphenyl-butadien entstehen in sehr guter Ausbeute 5.6-Dimethyl-3-acetyl-2-carboxy-bzw. 1.4-Diphenyl-3-acetyl-2-carboxy-1.2.3.4-tetrahydro-benzol. Auserdem wird die Addition von α-Methyl-β-athyl-acrolein an 2.3-Dimethyl-butadien beschrieben.