2-Pentylmagnesium bromide

Out first example is 2-hydroxy-2-methyl-3-octanone. 3-Octanone can be purchased, but it would be difficult to differentiate the two activated methylene groups in alkylation and oxidation reactions. Usual syntheses of acyloins are based upon addition of terminal alkynes to ketones (disconnection 1 see p. 52). For syntheses of unsymmetrical 1,2-difunctional compounds it is often advisable to look also for reactive starting materials, which do already contain the right substitution pattern. In the present case it turns out that 3-hydroxy-3-methyl-2-butanone is an inexpensive commercial product. This molecule dictates disconnection 3. Another practical synthesis starts with acetone cyanohydrin and pentylmagnesium bromide (disconnection 2). Many 1,2-difunctional compounds are accessible via oxidation of C—C multiple bonds. In this case the target molecule may be obtained by simple permanganate oxidation of 2-methyl-2-octene, which may be synthesized by Wittig reaction (disconnection 1). 

The well-known Robinson-Schbpf reaction has been applied to the synthesis of JZ-adaline (107) from ketoglutaric acid (457), ammonium chloride, and keto-aldehyde (458) (Scheme 58) 338). The second synthesis of starts with nitrone 459 462). Reaction of 459 with pentylmagnesium bromide gave a hydroxylamine (460) which was oxidized to yield a mixture of nitrones 461 and 462. Without separation of the nitrones (461 and 462), successive treatments with allylmagnesium bromide and then mercuric oxide gave a mixture of desired nitrones 466 and 467 and by-product 468. Nitrones 466 and 467 are capable of 1,3-dipolar cycloaddition and, on heating in chloroform, 466 and 467... 

Enthalpies of formation of the magnesium bromide salts of the Bronsted acids are calculated from the measured enthalpies of the reaction of the Bronsted acid, HB, with pentylmagnesium bromide and the known enthalpies of formation of pentyhnagnesium bromide and pentane according to equation 11. Because some of the HB enthalpies of formation have been revised and others newly measured since the original publication, the BMgBr enthalpies of formation have been recalculated and appear in Table 4. ... 

Addition of DDTC extraction with pentane clean-up with 100% active alumina followed by elution with hexane/diethylether Derivatisation with pentylmagnesium bromide Separation by CGC detection by MS (Lab. 06)... 

Methyl-3-decen-5-ol is prepared by Grignard reaction of pentylmagnesium bromide and 2-methyl-2-pentenal [14]. 

Silylated glutaconaldehyde (36) has been used as a five carbon homologating agent for the synthesis of pellitorine (1) and sarmentine (3) by reaction with w-pentylmagnesium bromide followed by oxidation to the corresponding acid and final amidation [58] (Scheme 14). 

CO2 + 5% MeOH, 0.92 g/ml, 365 atm, 45°C, 20 min static, 30 min dynamic, 2 ml/min Direction of fluid flow up extraction vessel orientation vertical SFE extracts collected in (i) Isco 15 ml methylene chloride, (ii) HP octadecyl-bonded silica trap and rinsed off the trap with 3 X 1.8 ml portions of methylene chloride extracts transferred to a 60 ml reparatory funnel and concentrated by nitrogen to a final volume of approximately 0.5 ml derivatization step extract treated with pentylmagnesium bromide (PMB) to convert the ionic organotin compounds into their neutral derivatives Extraction parameters studied... 

Second method ca. 0.5 g sediment was extracted with methanol/tropolone after addition of HCI. Tripropyltin was added as internal standard. Derivatiza-tion was performed by addition of pentylmagnesium bromide (2 mol L ) followed by clean-up with silica gel. Separation was by CGC (column of 25 m length, 0.2 mm internal diameter, methylphenyl silicon as stationary phase, 0.11 pm film thickness He as carrier gas at 130 mL min injector temperature at 260 °C column temperature ranging from 80 to 280 °C detector (transfer line) temperature at 280 °C). Detection was by mass spectrometry. Calibration was by calibration graph, using butyltin chloride compounds as calibrants. 

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