Butylmagnesium bromide, reaction with

The even more sterically hindered Grignard reagent, fcrr-butylmagnesium bromide, reacts with benzophenone (Scheme 5) to give a ring-substituted product in high yields [2b,9] in a very fast reaction. 

Furthermore the CuCN catalyst is more regiospecific with the use of n-butylmagnesium bromide than with t-butylmagnesium bromide. The reaction with phenylmagnesium bromide also showed an excellent regioselectivity in favor of the 5 2 product. 

SoUadid has introduced a-sulfinyl acetates as reagents for asymmetric aldol reactions.Compound (211) is prepared in good optical purity from the menthyl ester of p-tolylsulfinic acid. The magnesium enolate of (211), prepared by reaction of the sulfrnyl ester with r-butylmagnesium bromide, reacts with aldehydes and ketones to give diastereomeric mixtures of a-sulfinyl-3-hydroxy esters (Scheme 13). No... 

The rate of the reaction decreases with increasing number of substituents in the acetylenic halide, and it is higher with acetylenic bromides than with the corresponding chlorides. Methyl magnesium iodide gives equal amounts of 1,1- and 1,3--substitution products, whereas tert.-butylmagnesium bromide does not react. However, for some tert.-butyl substituted allenes there exists an attractive com-... 

The actual mechanism by which a particular reaction proceeds strongly depends on the nature of the organomagnesium reagent. For instance benzophenone reacts with methylmagnesium bromide by a polar mechanism, while the reaction with t-butylmagnesium chloride proceeds for steric reasons by a SET-mechanism. 

Metalation ofa-sulfinyl dimethylhydrazones with terf-butylmagnesium bromide, butyllithium or lithium diisopropylamide, and reaction of the generated azaenolates with aldehydes, provides aldol adducts (e.g., 6) as mixtures of diastereomers. Reductive desulfurization leads to fi-hydroxy dimethylhydrazones (e.g., 7) which are cleaved to the desired /(-hydroxy ketones in 25% overall yield10 u. The enantiomeric excesses are about 50%, except for (- )-3-hydroxy-4-methyl-1-phenyl-1-pentanone (8) which was obtained in 88% ee. 

In this series, too, replacement of the N-methyl by a group such as cyclopropylmethyl leads to a compound with reduced abuse potential by virtue of mixed agonist-antagonist action. To accomplish this, reduction of 24 followed by reaction with tertiary butylmagnesium chloride gives the tertiary carbinol 27. The N-methyl group is then removed by the classic von Braun procedure. Thus, reaction with cyanogen bromide leads to the N-cyano derivative (28) hydrolysis affords the secondary amine 29. (One of the more efficient demethylation procedures, such as reaction with ethyl chloroformate would presumably be used today.) Acylation with cyclopropylcarbonyl chloride then leads to the amide 30. Reduction with lithium aluminum hydride (31) followed by demethylation of the phenolic ether affords buprenorphine (32).9... 

The finely divided hydride produced by pyrolysis is pyrophoric in air, while synthesis from the elements produces a substantially air-stable product [1]. That prepared by reduction of butylmagnesium bromide with lithium tetrahydroalumi-nate is pyrophoric and reacts violently with water and other protic compounds [2], The hydride produced from magnesium anthracene has a very large specific surface area and is pyrophoric [3], In the context of use of the hydride for energy storage purposes, ignition and combustion behaviour of 100-400 g portions were studied, as well as the reaction with water [4],... 

Precursors for this task were obtained by addition of /-butylmagnesium bromide to the central bond of [1.1.1 ]propellane 40a followed by conversion of the 3-f-butylbicyclo[ 1.1.1 Jpentyl-1 -y 1-magnesium bromide (88) into the ketones 89 by standard methods.27 Reaction of ketones 89 with tosyl hydrazide afforded the hydrazones 90, which gave the corresponding lithium salts 91 by reaction with MeLi in ether. These salts were dried under high vacuum and then pyrolized at 4 x 10 5 torr in the temperature range of 100-130°C and the volatile products condensed in a liquid nitrogen-cooled trap. 

Butyl hypochlorite, warning, 44, 26 N-chlorination of amines with, 41, 82 n-Butyl isocyanide, 41,14 /er/-Butyl isocyanide, 41,14 -Butylmagnesium bromide, 41, 61 reaction with rec-butyl crotonate, 41, 61... 

To a stirred solution of 29 mg (0.2 mmol) of copper(I) bromide in 10 mL of diethyl ether under nitrogen are added 504 mg (4 mmol) of 3-[( R,R)- l,2-dimethyTl,2-ethanediylbis(oxy)]-l-propyne in 20 mL of diethyl ether. After cooling to — 50 °C lOmL (8 mmol) of a 0.8 M solution tert-butylmagnesium bromide in diethyl ether are added and the reaction is followed by TLC using cyclohexane. diethyl ether 90 10 as eluant. After completion, hydrolysis is achieved by the addition of 50 mL of aq NH3/NH4C1 and the product is extracted with diethyl ether. The solvent is evaporated and the pure product is stored over K2C03 yield 663 mg (90%) d.r. >98 <2. 

Intermediates 162 may be generated electrochemically,224,225 with zinc,219,221,223 sodium, potassium, magnesium,221 or organometallics.2,8,220 An electron-transfer mechanism for a reaction of perchlorate 158 with tert-butylmagnesium bromide was considered220 as follows (Eq. 7). 

The first detailed study of the stereochemistry of a mercury exchange reaction that was known to be bimolecular was carried out as follows.83 Di-j-butyl-mercury was prepared by reacting optically active j-butylmercuric bromide with racemic i-butylmagnesium bromide as shown in Equation 4.48. 

Apart from the oxidation of trihexylborane,16 1-hexanol has been prepared by a previous Organic Syntheses17 procedure involving the reaction of ethylene oxide with n-butylmagnesium bromide and alternate methods of synthesis are reviewed therein. 

One of the first detailed studies on these systems was that of Beaman (26), who showed that methacrylonitrile polymerizes by an anionic chain mechanism when treated with various bases, including Na in liquid ammonia at —75° C. He noted also that low molecular weight polymers are obtained from reaction of acrylonitrile with butylmagnesium bromide. Foster (56) extended the liquid ammonia method to copolymerization studies in which acrylonitrile was combined with styrene, with methyl methacrylate and with vinyl butyl sulfone. Satisfactory data were obtained only with the sulfone, in which case there was some tendency for alternation. 

Directed coupling reactions, where no cross-coupling may occur, requires the reagents derived from the appropriate synthons to be ionically different at the reactive site. The carbon-carbon coupling reaction to form hept-l-ene (Expt 5.8), illustrates the importance of selecting the reactive, and readily available, allyl bromide (cationic site) with butylmagnesium bromide (anionic site) (A), rather than the other alternative (B). 

The addition of lithium bromide significantly increases the thermal stability of alkylsilver compounds.14 Westmijze and coworkers found that the reaction of n-butylmagnesium bromide, for example, with AgBr2LiBr gave a solution of butylsilver that was stable up to — 10°C, which is in stark contrast to the species obtained from the reaction with silver bromide alone, which decomposes at — 60°C. This marked stabilization of the alkylsilver compounds allowed for the first meaningful use of these reagents in intermolecular reactions. 

---