Isopropylmagnesium bromide

The procedure described is essentially that of Lawesson and Frisell.4 2-Hydroxythiophene has been prepared in low yields by Hurd and Kreuz 5 from 2-thienylmagnesium bromide and oxygen in the presence of excess isopropylmagnesium bromide. 

The magnesium enolates are prepared by treatment of malonic acid half ester either with magnesium ethylate[24],[32] or with isopropylmagnesium bromide[24] or chloride.t26] Ref. [23] describes the synthesis of a 13C-labelled ethyl acetoacetate. Concerning the synthesis of porphyrin / -ketoesters,[3 1 it was noticed that the method via imidazolides is more efficient than the other approach via acid chlorides and sodiomalonic esters. 

A trapping experiment of the optically active triorganotin chloride (5) with isopropylmagnesium bromide did give the expected methylneophylphenylisopropyltin (9) in a 20% yield but unfortunately, this tetraorganotin compound, which is optically stable (see Table 1), was obtained as a racemic mixture. 

In situ magnesiation of an allenyl iodide with isopropylmagnesium bromide gives rise to a transient allenyl Grignard reagent, which adds to aldehydes and ketones to afford mainly homopropargylic alcohol adducts (Table 9.8) [18]. The anti diastereo-mers are favored, especially with sterically demanding aldehydes. Additions to ketones are less selective. 

Cyclopentolate Cyclopentolate, 2-(dimethylamino)ethylic ester of 1-hydroxycyclopentane-a-phenylacetic acid (14.1.39), is synthesized by the esterification of a-(l- droxycylopentyl) phenylacetic acid (14.1.38) using 2-dimethylaminoethylchloride, a-(l- Hydroxycyclopentyl) phenylacetic acid (14.1.38) is synthesized by reacting the sodium salt of phenylacetic acid with cyclopentanone in the presence of isopropylmagnesium bromide [30]. 

In a related organometallic approach, treatment of the diiodoarylformamidine 878 with isopropylmagnesium bromide gave an organomagnesium intermediate which reacted with a variety of alkyl, allyl, and aryl isocyanates to give 3-substituted-8-iodo-4(37/)-quinazolinones 879 <20020L1819>. 

Alternatively, metalation of cyclohexanone imines can be performed with isopropylmagnesium bromide by refluxing in THF for 2 hours1,24. Alkylation of the magnesium azaenolate of the (E)-2-amino butyl ether derivative at —78 °C provides (E)-2-methylcyclohexanone in an overall yield of 52% and 81% enantiomeric excess24. 

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). 

The same strategy used by Barrero et al. for synthesis of the fungic metabolite LL-Z1271a (63) was used to synthesize nagilactone F (55). Thus, starting from the mixture of communic acids, lactol 99 is achieved, an immediate precursor of both 55 and epimer 165, which are obtained by treatment with isopropylmagnesium bromide. Thus, the synthesis of nagilactone F (55) is completed, with an overall yield of 10%. (Scheme 15). 

The reductive coupling of phenacyl bromides using nickel carbonyl (68CC33) or an electrolytic procedure (81S625) provides excellent yields of 2,4-diarylfurans. Coupling of a-bromoaldimines with sodium or lithium provides mainly 3,4-disubstituted pyrroles, whereas isopropylmagnesium bromide yields mainly 2,4-disubstituted pyrroles (Scheme 77)... 

Desulfuration.2 Vinyl sulfides arc reduced to the corresponding alkene by isopropylmagnesium bromide in the presence ol [(C6H5)3P]2NiCl2. No overreduction in observed, as frequently noted in reductions with Raney nickel. 

Evidence in support of this mechanism is provided by using the deuteride DCo(CO)4 as catalyst, when CH2DCH2CHO is the only deuterium-containing organic product of the reaction. In the isomerisation of isopropylmagnesium bromide the mechanism appears to be... 

The first arene osmium(O) complex 229 has been obtained by treating OsCl3 and 1,3-cyclohexadiene with isopropylmagnesium bromide followed by UV irradiation (119). 

Isopropylmagnesium bromide (2.5 m in ether, 0.36 ml) is added to a solution of (lS,2R,4R)-2-(2-methoxyethoxy)methoxy)-6-methylene-bicyclo[2.2.2]octane (68 mg, 0.3 mmol) in toluene (2.0 ml). The mixture is heated under reflux for 15 min (during which time a white precipitate forms). The mixture is cooled to room temperature, and water (10 ml) is added. The product is isolated via ether extraction (X3), chromatography and Kugelrohr distillation (150-160°/30 torr) as a colourless oil (47.2 mg, 81%). 

Dibutyl ether as the solvent. The use of isopropylmagnesium bromide leads to some halogen exchange. It is noteworthy that this old work has scarcely been bettered [6], Together with tetramesityldiphosphine (6%). 

The dark blue crystalline l,3-bis(dimethylamino)pentalene (157) was the second derivative to yield to synthesis (Scheme 26).233-1 Upon condensation of sodium cyclopentadienide with the salt 153, there is obtained the fulvene 154 which can be cyclized with loss of dimethylamine when heated in xylene. Treatment of the resulting ketone (155) with dimethylammonium perchlorate afforded the salt 156 which was successfully deprotonated with isopropylmagnesium bromide. Interestingly, 155 could be reversibly converted to its blue-colored enolate without polymerization or decomposition. 

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. 

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