Fragmentierungsreaktionen an Carbonylverbindungen mit β‐ständigen elektronegativen Substituenten, XXVII. Bicyclo[3.1.1]‐ und ‐[3.2.0]hept‐2‐enone aus 2‐Tosyloxymethyl‐3‐cyclohexen‐1‐onen

Abstract

p K p t -a from 2 -T~y l o X~e t h y l -3 -c~C l~X~l~Tosyloxymethyl-cyclohexenones 8n, 9 and 10 are prepared from 2-hydroxy-I-naphthoic acid in several steps. 8n reacts with aequous rnethanolic sodium hydroxide to give the bicyclo-[3.l.l]heptenone 11, the bicyclo[3.2.0]heptenones 12 and 13 as well as the acid 14. In this reaction 13 arises from 11 by thermal or acid catalysed rearrangement. Similarly from 9 or 10 the ketones 15,16, and 17 or 18,19, and 20 are formed. Fragmentation products could not be obtained. The mechanism is discussed.Bei der Solvolyse von 2-Tosyloxymethyl-1 cyclohexanonen 1 wurden als Hauptprodukte die Bicycloheptanone 2 und 3 und nur als Nebenprodukt die 6-Alkyl-6-heptensiiuren isoliert 3).

Stereocontrolled Synthesis of Kelsoene by the Homo-Favorskii Rearrangement

“…While the former ketone represents the product of the homo-Favorskii rearrangement, the latter corresponds to that of the direct displacement of the tosylate group by the ketone enolate. However, it is of considerable interest to note that, in general, the bicyclo[3.1.1]heptanone products readily rearrange to bicyclo[3.2.0]heptanones upon treatment with mild acid (vide infra), presumably a manifestation of their relative strain energies . Despite detailed mechanistic understanding and the potential access to synthetically versatile ring structures, this reaction has been scarecely exploited by practicing synthetic chemists.…”