Ueber die Lactone der Desylessigsäure

Abstract

T h i e l e u. S t r a u s , Ueber die Lactolze der Desybessigsazcre. 155 Die oben besprochenen und in den folgenden Abhandlungen naher angefiihrten experimentelleiz Daten durften wohl genugen, um die Strzccturisornerie der beiden Reihen von Crotonlactonen gegenuber den durch keinerlei Experimente gestutzten Annahmen E r l e n m e y e r ' s ebenso sicher zu stellen, wie die Structurisomerie der d i -und d2-ungesattigten Siiuren von anderer Seite sicher gestellt worden ist.Thiele u. S t r a u s , Ueber die Lactone der Desylessigsaure. 157

A total synthesis of racemic avenaciolide

“…The 1H NMR spectra of compounds 17-20 suggested that exclusive trans addition of 16 to 3 had occurred. Conjugate addition of 16 to 3 followed by quenching with iodine gave a mixture of the adducts 21 and 22. The juxtaposition of the «-octyl, 2-thiomethylpropionate, and iodine substituents in these compounds clearly was all-trans as revealed by their NMR spectra as well as by their ultimate conversion into avenaciolide.…”

“…The juxtaposition of the «-octyl, 2-thiomethylpropionate, and iodine substituents in these compounds clearly was all-trans as revealed by their NMR spectra as well as by their ultimate conversion into avenaciolide. Lactonization of a mixture of 21 and 22 was achieved in the following manner. The iodolactone esters were heated in benzene containing a small amount of p-toluenesulfonic acid to give the iodolactone acids 23 and 24.…”

Ring-Chain Tautomerism of the cis--Benzoylphenylacrylic Acids

“…This acid has been prepared by the decarboxylation of the aldol condensation product of benzil and malonic ester (8), the hydrolysis of y-bromo-P, y-diphenylcrotolactone (9), and more recently by the Friedel-Crafts reaction between phenylmaleic anhydride and benzene (10,11). It is known to react in the cyclic (VIA) and acyclic (WB) senses giving derivatives of both types.…”

“…The acid IV had been obtained as an intermediate in the synthesis of I (2, 3) and X was made by a zinc-acetic acid reduction of VI (9). of dry benzene was added over a period of 1 0 1 5 minutes a solution of 5 g. of phenylsuccinic anhydride in 25 ml.…”

Notes- Ultraviolet Absorption Spectra of Some Ortho-Anisyl Esters and Thiolesters

“…from p-chlorobcnzonitrilc (A,,,,* = 237.5 mp )i to p-chloronitrobenzene (Am!1I = 280 mp) 4 the shift (42.5 mp) is almost identical to that (44.5 nig) resulting on passing from benzonitrile (A™,* = 224 mg)4 to nitrobenzene (A,ray = 268.5 mp).4-6 Spectroscopic indication of the enlargement of the iff-shell of a sulfur atom flanked by a carbonyl group has now also been presented by Knott.0a However, Knott,6b in commenting on the ultraviolet absorption spectra of aryl thiolesters, points out that since such molecules are not planar, contributions involving a sulfur decet are hindered or excluded. This objection is answered in a simplified way, schematically represented in Fig.…”