Cyclopropylmagnesium

The electrophilic reaction of magnesium cyclopropylidene (113) with Ai-lithioaryl-amines was reported (equation 31) . Thus, electrophilic reaction of magnesium cyclopropylidene (113) derived from 112 with iV-lithio iV-methyl p-anisidine resulted in the formation of a-amino-substituted cyclopropylmagnesium (119) in good yield. Methanol-ysis of the reaction mixture with CH3OD gave a-deuteriated Af-cyclopropyl-Af-methyl-p-anisidine (120) in 82% yield with 98% D-content. 

The reactivity of the formed a-amino-substituted cyclopropylmagnesium (119) with some electrophiles was investigated . Cyclopropylmagnesium (119) was found to have a low nucleophilicity and, for example, reaction with benzaldehyde gave only 40% yield... 

The square pyramidal complexes of group 9 iridium cyclopropylbis(>/4-diene) complexes were recently synthesized in poor yields (3-5%) by metathesis reaction between (tf-diene)2 IrCl and cyclopropyllithium or cyclopropylmagnesium bromide (equation 16)45. 

Similarly, group 10 trigonal nickel complex Cp(PPh3)Ni(c-Pr) was prepared from Cp(PPh3)NiCl and cyclopropylmagnesium bromide46. This complex, in analogy with the... 

The reaction of metals with alkyl halide to form alkylmetal compounds is typical for lithium and magnesium. This so-called direct synthesis was applied to the preparation of both cyclopropyllithium" and derivatives and cyclopropylmagnesium halides under the standard preparative conditions of Grignard reagents without ring cleavage (equation 1). 

The reverse photoreaction, i.e. the photocyclization of cinnamylmagnesium bromide to the corresponding cyclopropylmagnesium bromide, has also been described ... 

In all experiments acid 17 was obtained with overall retention of configuration. An interesting effect of the halogen is revealed. Retention of optical activity or configuration decreases in the direction Cl>Br I, with cyclopropylmagnesium iodide being essentially racemic. The yield of acid varies in the same direction, Cl>Br I, and the product hydrocarbons are very nearly racemic. 

Cyclopropylmagnesium Bromide Product Balances, Calculated and Found... 

Table 17 Yields of Cyclopropane Formed Directly During Formation of Cyclopropylmagnesium Bromide in the Reaction of Cyclopropane with Magnesium...

Addition of other unsaturated Grignard reagents leads to rather poor product yields. In addition to the 1 1 adducts 3, the formation of higher molecular weight products, e.g. 4, by further addition of the derived cyclopropylmagnesium halide to the starting cyclopropene, was ob-served. ... 

Allylmagnesium halides 2 cyclized to cyclopropylmagnesium halides 3 on irradiation of an ethereal solution for one day at 0- 5 C with a high-pressure mercury lamp in a quartz apparatus. Treatment of the irradiated mixture with solid carbon dioxide and subsequent hydrolysis gave cyclopropanecarboxylic acids 4 as the major photo-products, representing 45-75% of the acidic products (absolute yields not given). 

The cyclopropylmercury derivatives which have been isolated, have been synthesized by treating the corresponding cyclopropyllithium or cyclopropylmagnesium halide with a mercury dihalide the yields vary considerably. treatment of A.A-dlisopropyl-l-methylcyclopro-... 

By converting cyclopropyllithium intermediates to cyclopropylmagnesium bromide species and subsequent addition of approximately 1% of a nickel catalyst, [l,2-bis(diphenylphosphino)-ethane]nickel dichloride [Ni(dppe)Cl2], the tricyclo[4.1.0.0 ]hept-l-yl and similar anions were... 

Cyclopropylmagnesium bromide is reactive enough to transform esters to the corresponding tertiary alcohols, albeit in moderate yields only. This has been utilized in a couple of cases. Thus, when ethyl diphenylacetate and methyl dicyclopropylacetate were used as electrophiles, l,l-dicyclopropyl-2,2-diphenylethanol (6) and 1,1,2,2-tetracyclopropylethanol (7), spectively, were both isolated in less than 50% yield. 

A limited number of bromocyclopropanes have been converted to a variety of functionalized alkenes with the ring attached to the C-C double bond. With the exception of an iron-mediated substitution of cyclopropylmagnesium bromide to bromomethylenecyclopropane, which leads... 

Many cyclopropyl halides, mainly bromides, but also some chlorides, have been converted to alkylcyclopropanes by replacement of the halide. The yields reported are usually well above 50%. Several types of reactions have been utilized to achieve such substitution. When simple halocyclopropanes are used, the halides are converted to the corresponding cyclopropyllithium compounds or cyclopropylmagnesium halides, which undergo alkylation when treated with electrophiles such as alkyl halides, dimethyl sulfate, and tropenylium tetrafluoroborate. Following this strategy 3-bromo-l,l,2,2-tetramethylcyclopropane, bromocyclopropane and (la,2/I,3a)-1-bromo-2,3-dimethyl-l-phenylcyclopropane were transformed to 1,1,2,2,3-penta-... 

The reaction of diarylcyclopropenones 1 with aryl- or cyclopropylmagnesium °° bromide and hydrolysis using aqueous potassium dihydrogen phosphate solution, followed by treatment with a strong Bronsted acid such as tetrafluoroboric - or hydrobromic acid, afforded the trisubstituted cyclopropenylium salts 26. 

The reaction of gem-dibromocyclopropanes with "TiUjMgJi provides the butylated cyclopropylmagnesium species, which react with a variety of electrophiles (Tab. 3.19 and 3.20). 

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