1 - bicyclo hexane cyclopentanone

It has been observed that the formation of the olefin and carbon monoxide, 45, is ten times more important than the formation of the bicyclic hydrocarbon and carbon monoxide, 46, at 80° and 80 mm. pressure even at 3130 A. The formation of the strained bicyclic hydrocarbon is evidently not a favorable reaction although this may not be the only consideration. In the case of camphor it should be interesting to find out if an optically active isomer of the ketone on photolysis will give rise to an optically active trimethyl bicyclo [2.1.1] hexane (XXVI). A concerted reaction, analogous to the formation of cyclobutane from cyclopentanone, may lead to only an optically active product. 

Ethyl 4-(/cr/-butyldimethylsiloxymethyl)-l-(trimethylsiloxy)bicyclo[3.1.0]hexane-6-carboxy-late (1) reacted with chlorotrimethylsilane to give the desilylated 2-(ethoxycarbonylme-thyl)cyclopentanone derivative 2 by cleavage of the original donor-acceptor-substituted bond. ... 

When bicyclo[3.1.0]hexan-2-one was refluxed with pyridinium chloride in acetonitrile a mixture of 4-chlorocyclohexanone (4) and 3-(chloromethyl)cyclopentanone (5) was obtained. ... 

A fruitful method for formation of 3-substituted cyclohexanones 26 utilizes a one-carbon ring-expansion process starting from 2-substituted cyclopentanones 23. A bromomethyl, iodo-methyl, or phenylselanylmethyl group is introduced at C2 in the jS-position by base-catalyzed alkylation. Treatment of the resulting 2,2-difunctionalized cyclopentanone 24 with tributyltin hydride generates a bicyclo[3.1.0]hexan-l-oxyl radical 25 as a transient intermediate which rearranges and abstracts hydrogen to construct the 3-substituted cyclohexanone 26. 

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