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 phenolic diazoketones (7; n
= 3-7) were treated with boron trifluoride etherate in nitromethane. For n = 4, 5 and 6 spirodienones
(8) were isolated as well as the respective benzocycloalkanones
from a concomitant dienone-phenol rearrangement. The formation of (8; n = 4) constitutes the first
demonstrated example of Ar1-4 participation.
The tricyclic dienones
(14), (16), and (16) have been prepared by the Ar1-6
cyclization of a diastereomeric mixture of 7-[(2?-bromo-1?- tetrahydropyranyloxy)-ethyl]-5,6,7,8-tetrahydro-2-naphthols
(11) and of 7-diazoacetyl-5,6,7,8-tetrahydro-2-naphthol (17). Intermediates
(11) and (17) were prepared by standard procedures from 1,2,3,4-tetrahydro- 7-hydroxy-2-naphthoic
acid.
A new method is described
for the preparation of tricyclic compounds containing the 3,2,1- and
2,2,2-bicyclooctane ring systems. The copper-catalysed decomposition of the
diazomethyl ketones derived from the olefinic acids (7), (9), (18), and (19)
afforded, respectively, the cyclopropyl ketones (12), (13), (21), and (20).
These compounds were transformed into the cyolopropyl diketones (15) and (22)
which by treatment with dilute acid or base gave, in turn, the bridged
octalones (1) and (2).
Methanolyse der Säure (II) liefert das Acetal (Ia) (95% Ausbeute), das durch Behandlung mit Oxalylchlorid/Pyridin und nachfolgend mit Diazomethan das Diazoketon (Ib) gibt.
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).
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