Short Syntheses of some 'Decalin-1,8-diones' and their Derivatives: Breaking the Pretended Symmetry

Knorr, Rudolf; Nadolny, Annette; Hauer, Hermann und Boehrer, Petra (2019): Short Syntheses of some 'Decalin-1,8-diones' and their Derivatives: Breaking the Pretended Symmetry. In: Helvetica Chimica Acta, Bd. 102, Nr. 6, e1800231

Abstract

A cheap synthesis of the so-called 'decalin-1,8-diones' started with the conjugate (1,4-) addition of cyclohex-2-en-1-one derivatives to the gamma-position of the dilithium derivative (buta-1,3-diene-1,1-bis(olate)) of crotonic acid. Hydrogenation of these '1,4-gamma' adducts and final cyclization afforded the enol tautomers of decalin-1,8-diones. Nucleophilic substitutions at these 3-oxoenols by NH3 or primary amines created only monoamino products (namely, 3-oxoenamines) whose reactions with OPCl3 yielded dihydro(1,3,2)oxazaphosphinin-2-one derivatives. The two regioisomers of a trimethyl-3-oxoenamine served as models for the constitutional assignments of the two rapidly interconverting (hence, individually NMR-invisible), tautomeric trimethyl-3-oxoenols. Such methyl substitutions served to break the 'pretended' symmetry of 'decalin-1,8-dione'. Hydrazine and 3-oxoenols furnished oxygen-free indazole derivatives whose N-H bonds exchanged with t(1/2)=ca. 0.00035 s at ca. -58(9) degrees C.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Chemie und Pharmazie > Department Chemie
• Themengebiete: 500 Naturwissenschaften und Mathematik > 540 Chemie
• ISSN: 0018-019X
• Sprache: Englisch