The acid-catalysed reactions in weakly nucleophilic environments of 2-diazoacetyl-l,2,3,4-tetrahydronaphthalene (ll), of 6-diazoacetyl-5,6,7,8-tetrahydro-2-naphthol (2), of 6-diazoacetyl-5,6,7,8- tetrahydro-2-naphthyl methyl ether (3) and its 2,8 and 2,5 isomers (14) and (17), and of 6-diazo- acetyl-5,6,7,8-tetrahydro-6-trifluoroacetoxy-2-naphthyl methyl ether (9) have been studied. Several of the spirocyclohexa-2,5-dienone derivatives prepared thus, (4), (8) and (16), provide potential intermediates or models for the synthesis of tetracyclic diterpenoids.

The 1,2,3,4,9,10-hexahydrophenanthrenecarboxylic acids (9), (10) and (12) have been prepared and converted via their diazomethylcarbonyl derivatives to the 1,2,3,9,10,10a-hexahydro-2,l0a-ethano- phenanthren-12-one derivatives (2), (3) and (4), respectively, by short and efficient routes.

No abstract

Methods for the conversion of 12-hydroxypodocarpa-8,11,13-trien-19-oic acid (1) into the α,β-unsaturated ketones (6) and (7) have been investigated. Lithium in liquid ammonia reduction of the ester (19) and the hydroxy acid (24) with concomitant decarboxylation gives moderate yields of the desired products. The ketone (7) has also been prepared in improved yield by a modification of Bible and Burtner's method involving the intermediates (9), (35), (12), (16), (17), and (18).

Die durch Trifluoressigsäure katalysierte Cyclisierung der Tetranaphthyl‐diazomethylketone (I), (III), (V), (VIII) bzw. (XI) liefert die tricyclischen Ketone (II), (IV), (VI) (IX) und (X) bzw. (X).