Alkylation of Cyclopropyl Ketones

Section 1.1.1.3.1.1.2.1.). Similarly, the reductive ring opening of cyclopropyl ketones, e.g., 8, with lithium in ammonia affords specific enolates20,21. These enolates can, of course, be used for selective alkylation. Furthermore, enol acetates, e.g., 10, are regiospecifically obtained by nucleophilic ring opening of cyclopropyl ketones21. 

Alkylation of nonenoRzable ketones. Potassium hydride in THF reduces cyclopropyl phenyl ketone however, in the presence of cryptate [2.2.21 (1 equivalent) the ketone can be alkylated in high yield (equation I). 

Acceptor ability of a group can be enhanced by interaction with a suitable electrophile (proton, Lewis acid). This is very likely in the Ni(acac)2-catalysed reaction of cyclopropyl ketones with trimethylaluminium and in the synthetically more significant addition of several cuprates to alkyl cyclopropyl ketones. The BFs-activated organometallic reagent attacks the less substituted cyclopropane carbon regioselectively. Yet steric hindrance can be a problem in this reaction (equation 40) . 

Reaction of diorganocuprates with a,a -dibromo ketones provides a new method for the a-alkylation of a ketone a nucleophilic attack of the cuprate on the intermediary cyclopropanones could explain the reaction (Posner and Sterling, 1973 Posner et al., 1973). The cyclopropyl group can be introduced at the alpha position of ketones as well (Carlson and Mardis, 1975). 

Cyclopropyl-2-hydroxyalkyl sulphoxides 416 can be obtained either by addition of an a-sulphinyl carbanion to a cyclopropyl ketone, or from alkyl 3-chloropropyl ketones and two moles of an a-sulphinyl carbanion493 (equation 247). 

Triple-bond participation has been mainly studied (by Hanack and his school) in reactions of homopropargyl derivatives 31 under solvolytic conditions. In all cases of Table 3, except 1 and 2, compounds 31 yield, besides (and very often instead of) the expected solvolysis products, cyclobutanone derivatives (32) and alkyl cyclopropyl ketones (33). 

The successive treatments of 3-butynyl sulfonates with alkyllithium and trialkylborane afford 4-alkyl-4-borylmethylenecyclopropanes, which provide cyclopropyl ketones upon oxidation (equation 32) . The 3-butynyl sulfonates react also with PhMc2 SiMgMe/CuI... 

Another successful alkylation of a cyclopropyl ketone was reported by Handel and CO workers when they reacted cyclopropyl phenyl ketone (211) with excess potassium hydride (5 M equivalents) in the presence of [2.2.2]cryptand methylation with methyl iodide gave 212 in 90% yield. The conditions are crucial without the cryptand, 211 is reduced to the corresponding secondary alcohol in 82 % yield. 

Cyclopropylamines were also obtained from cyclopropanecarboxylic acids (73, R = OH), hydrazoic acid and sulfuric acid in a Schmidt reaction Cyclopropyl ketones (73, R = alkyl, aryl) as starting materials in the Schmidt reaction gave rise to a mixture of two isomeric amides (74 and 75) (equation 12). From ketones with an... 

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