Metal-ammonia ring reductions have been carried out with 9-acetyl-10-alkylanthracenes, 10-alkylanthroate esters, l-acetyl-4-alkylnaphthalenes, 4-alkylnaphthoate esters, and p-tert-butylbenzoic acid. The stereochemistry of these reactions is determined by the protonation of the final monoanion. A model is suggested which involves considerable enolate character, as well as a variation in the extent of ring folding. In general, dihydroanthracene anions are the most highly folded and provide cis products, dihydronaphthalenes have intermediate folding and produce cis/trans mixtures, and p-tert-butyldihydrobenzoate dianion is planar and produces trans products. NMR methods for isomer assignment and conformational analyses are also provided.The protonation (and alkylation) of monoanions derived from dihydroanthracenes, -naphthalenes, and -benzenes has received considerable attention.1 These anions may be generated by deprotonation of the dihydro aromatics (1) or by electron addition to the fully aromatic compounds (2) . In the latter case, these monoanions represent the final intermediate in dissolving metal reduction (or reductive alkylation). In either case, it is the protonation (alkylation) of this intermediate that determines stereochemical (cis/trans) outcome.The most heavily studied case has been the dihydroanthracene system, and early observations1®-0 of trans products from the protonation of 9-metallo-9,10-dialkyl-9,10-dihydroanthracenes (DHA's) led to thé model shown as anion 3. This seemed reasonable, since (1) the DHA (1) (a)

Während die Reduktion der Anthracene (I) mit Natrium in flüssigem Ammoniak fast ausschließlich zu den cis‐Dihydro‐Derivaten (II) führt, entstehen aus den Naphthalinen (III) Gemische aus den trans‐ und cis‐Verbindungen (IV) und (V).