Isopropylmagnesium bromide, reaction with

The protocol is used for the preparation of 25 kg of the aldehyde in Banyu, and applied to the synthesis of a muscarinic receptor agonist. It is noteworthy that halogen-metal exchange reactions with other metal reagents such as butyllithium or isopropylmagnesium bromide led to more complex mixtures. The Banyu protocol was applicable to similar monoformylation reactions of dibromoheteroarenes (Table 12). 

Greenwood91,92 demonstrated the formation of primary ozonides in the reaction of some reaction with liquid ozone gave products that formed glycols on mild reduction with isopropylmagnesium bromide. On the other hand, primary ozonides have not been detected with certainty in the case of cis-olefins.88 91 The reaction of cis-3-hexene,93 eis-2-butene, cis-2-pentene, and ethylene92 with ozone at —112° in pentane led to extremely explosive substances, which could be primary ozonides. In the... 

Bis(6,6-diphenylfulvene)cobalt(I) cation has been isolated as the PF( salt by reaction of the olefin with C0CI2 and isopropylmagnesium bromide followed by hydrolysis and air oxidation (216,227). On the basis of the infrared and NMR spectra structure (164), in which the two ligands are not identically bonded to the metal, has been assigned to the cation. 

A comparison of the results of reactions of n-propylmagnesium bromide and isopropylmagnesium bromide with (substituted) benzophenones [15b] led the authors to some conclusions that are presented in Table 4. 

The di-Grignard reagent 164, formed from l,2-diethynyl-l,l,2,2-tetraalkyldisilane, has been prepared by reaction with either ethyl- or isopropylmagnesium bromide [Eq. (73) 135,136]. Reactions of di-Grignard reagent 164 with 1,2-dichlorotetraalkyldisilanes and 1,3-dichlorohexamethyltrisilane produced cyclic polysilanes 165 and 166, respectively, in yields that were typically 37-73% [135-137]. 

Self-condensation reactions, as in the original Claisen reaction, are still synthetically valuable. The ester (106) was self-condensed with isopropylmagnesium bromide as the base and this product used in spherand formation (equation 30). ... 

Reaction with enol ethers. 2-Substituted dihydropyrans and dihydrofurans are reduced to the ( )-alkenols with isopropylmagnesium bromide in the presence of a nickel chloride complex. The reaction has been applied to a formal synthesis of recifeiolide. 

Cuprous [ Cu(I) ] salts are readily available and when mixed with Grignard reagents give excellent yields of cross-coupled products with very little disproportionation. This reaction will be discussed in greater detail in Section 8.7.A. However, a simple example is the reaction of isopropylmagnesium bromide with bromoethane in the presence of cuprous bromide (CuBr) to give 2-methylbutane. The origins of this reaction date... 

Tropolones. A new tropolone synthesis involves in the first step reaction of dimethyloxosulfonium methylide with the quinone monoketal 1 to form the cyclo-propyl ketone 2. Reaction of 2 with isopropylmagnesium bromide followed by dehydration and deketalization gives 3. On treatment with base, the enolate undergoes ring opening to form, after silylation, the dihydrotropolone derivative 4. This product is converted into 3-dolabrin (5) by oxidation followed by demethylation. 

A soln. of crude 2-(a-bromobenzyl)-2-norbornanol in anhydrous benzene treated at 0° with 1 equivalent isopropylmagnesium bromide, and refluxed 0.5 hr. 3-phenylbicyclo[3.2.1]octan-2-one. Y 64%. A. J. Sisti, Tetrah. Let. 1967, 5327 stereospecific introduction of angular methyl groups via this reaction s. Tetrah. Let. 1969, 2269. 

An additional important application of the Kharasch reaction is in the synthesis of polyaryls. For example, 2,5-dibromopyridine (140) was transmetallated upon treatment with isopropylmagnesium bromide to give the corresponding Grignard reagent 141, which subsequently underwent the Kharasch reaction affording the polypyridine (PPy) in 76% yield [43], respectively. Scheme 11. 

Scheme 5.4 Reaction of cyclohex-2-enone with isopropylmagnesium bromide.

Addition reactions of Grignard reagents to carbonyl compounds are also performed in microflow reactors. For example, the reaction of cyclohex-2-enone with isopropylmagnesium bromide leads to the formation of both 1,4-adduct A and 1,2-adduct B (Scheme 5.4). It is noteworthy that the microflow reactor serves a beneficial tool for optimization of the reactions conditions. By testing 14 different reaction conditions, the yield was increased from 49% to 78% and the ratio of the regioisomers was improved from 65 35 to 95 5 [12, 13]. 

Wang, Shi, and coworkers [70] reported the cobalt-catalyzed directed C-H alkylation of benzo[h]quinoHne with alkyl Grignard s reagents (Scheme 19.44). The reaction occurred at room temperature but proved less efficient and general than the corresponding C-H arylation. Interestingly, when isopropylmagnesium bromide was employed, a mixture of Hnear and branched products was obtained. The... 

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