Ketone, cyclopropylmethyl preparation

The biradical benzo-l,2 4,5-bis(l,3,2-dithiazolyl) (BBDTA) is known in the literature but characterization is incomplete. A new study reports the electronic, molecular, and solid-state structure of BBDTA.224 The lifetime of an alkyl phenylglyoxalate-derived 1,4-biradical has been estimated, using the cyclopropylmethyl radical clock , to be in the range 35—40 ns.225 The indanols (88) and their C(3) methyl and trideuteromethyl analogues have been prepared from phenyl benzyl ketone via photo-cyclization of an intermediate 1,5-biradical species.226,227 Selectivity for these products over their C(l) epimers is high but is profoundly effected by substitution in the benzyl ring or the alkyl side-chain. The findings are rationalized in terms of the conformational preference of the intermediate 1,5-biradicals. 

Cyclopropyl ketone 222 (Scheme 55) was prepared to probe the mechanism of the cleavage reaction [39,40]. Isolation of 224 where the cyclopropyl ring is intact (Scheme 56) suggests cleavage proceeds via formation of radical 227 rather than ketyl radical anion 226, formed by single-electron transfer to the ketone carbonyl, as cyclopropylmethyl radical anions are known to undergo facile fragmentation. 

Several cyclopropylmethyl cations have been prepared by treating cyclopropyl ketones with super acids at low temperature. The hydrogen fluoride/antimony(V) fluoride mixture has been most frequently employed, but hydrogen chloride in antimony(V) chloride and antimony(V) fluoride/fluorosulfuric acid/fluorosulfuric chloride have also been used. The counterion is, therefore, hexahaloantimonate. Yields were generally not reported an exception was the isolation of tricyclopropylmethylium hexafluoroantimonate in 86% yield on reaction of tricyclopropylmethanol with antimony(V) fluoride. " ... 

Manganese oxides are well-established oxidizing agents, which have been used for the conversion of cyclopropylmethyl alcohols to the corresponding carbonyl compounds. Activated manganese dioxide in an inert solvent has been employed to prepare aldehydes - as well as ketones,e.g. oxida-... 

An effort was made to prepare a butyl analogue containing a ring, but it was never completed. This was the cyclopropylmethyl isomer, 2,5-dimethoxy-4-cyclo-propylmethylamphetamine hydrochloride, DOCPM. Only the first step of its synthesis was complete (the reaction of cyclopropylcarboxylic acid chloride with p-dimethoxybenzene) and even it went badly. The desired ketone (2,5-dimethoxyphenyl cyclopropyl ketone) was most difficult to separate from the recovered starting ether. A promising approach would be the isolation of the phenol (2-hydroxy-5-methoxyphenyl cyclopropyl ketone) which is a beautiful yellow solid with a melting point of 99-100 °C from methanol. Anal. (Cl 1 HI203) C,H. It then could be methylated to the wanted intermediate. It is the major product when the reaction is conducted with anhydrous aluminum chloride in methylene chloride. 

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