Pentanone 4-bromo-4-methyl

In a similar way, dl-2-(q-hydroxyalkyl)- and 2-(a-alkoxycarbonyl)-4-methyl-5-(/3-hydroxyethyl)thiazoles were synthetized from the corresponding thioamides and 4-hydroxy-3-bromo-2-pentanone (615). 

A mixture of 22 parts of 1 -ethyl-1,4-dihydro-5H-tetrazol-5-one,45 parts of 1 -bromo-2-chloro-ethane,26 parts of sodium carbonate,0.3 part of potassium iodide and 240 partsof 4-methyl-2 pentanone is stirred and refluxed overnight with water-separator. The reaction mixture is cooled, water is added and the layers are separated. The aqueous phase is extracted three times with dichloromethane. The combined organic phases are dried, filtered and evaporated. The residue is purified by column-chromatography over silica gel using trichloromethane as eluent. The pure fractions are collected and the eluent is evaporated, yielding 28.4 parts (80%) of 1-(2-chloroethyi)-4-ethyl-1,4-dihydro-5H-tetrazol-5-one as a residue. 

In some cases, the Grignard reaction can be performed intramolecularly. For example, treatment of 5-bromo-2-pentanone with magnesium and a small amount of mercuric chloride in THE produced 1-methyl-1-cyclobutanol in 60% yield. Other four- and five-membered ring compounds were also prepared by this procedure. Similar closing of five- and six-membered rings was achieved by treatment of a 6- or s-halocarbonyl compound, not with a metal, but with a dianion derived from nickel... 

The reaction of ethyl A-arylcarbamates 3 with l-bromo-3,3-dimethyl-2-buta-none or l-bromo-3-ethyl-3-methyl-2-pentanone 4 in the presence of lithium bis(trimethylsilyl)amide (LiHMDS) results in the one-step synthesis of 3-aryl-5-ferf-butyl-2(3/T)-oxazolones 7 in fair to good yields (Fig. 5.2 Table 5.1, Fig. 5.3). This method is efficient for the preparation of bulky 5-substimted-2(37f)-oxazo-lones. 

Methyl-2-nitrosopropane dimer, 413 1 -Methyl-A8-octahydroquinoline, 111-112 yV-Methyl-A -octahydroquinoline, 111-112 Methyl orthoformate, 47, 54 Methyl orthovalerate, 48 2-Methyl-4-oximino-3-pentanone, 396 1 -(N-Methyl-7V-phenylamino)-2-bromo-propane, 105... 

Synthesis The cyclization of ethyl isocyanate with sodium azide by means of AICI3 in refluxing THF gives 1 -ethyl-1,4-dihydro-5H-tetrazol-5-one, which is alkylated with 1-chloro-2-bromo-ethane in the presence of Na2CC>3 and Kl in refluxing 4-methyl-2-pentanone to afford 1-ethyl-4-(2-chloroethyl)1,4-dihydro-5H-tetrazol-5-one i (Janssen (Janssen), 1978 Janssens et al., 1986 Hopkins, 1981 Kleemann et al., 1999). 

Synthesis (Kleemann et al. 1999, Janssen (Janssen), 1973 Janssen et al. (Janssen), 1973, Stokbroekx et al., 1973, Niemegeers et al., 1974) ) Treatment of 2-oxo-3,3-diphenyl-tetrahydrofuran, synthesized by treatment of diphenyl-acetic acid ethyl ester with ethylene oxide, with HBr(gas) yields bromo derivative i, which is then converted into butyryl chloride derivative ii by means of thionyl chloride in refluxing chloroform. Reaction of derivative ii with dimethylamine in toluene affords dimethyl (tetrahydro-3,3-diphenyl-2-furylidene)ammonium bromide, which is then condensed with 4-(4-chlorophenyl)-4-piperidinol by means of Na2C03 and Kl in refluxing 4-methyl-2-pentanone to provide loperamide. 

A mixture of 6.9 parts 4-bromo-2,2-diphenylbutyronitrile, 5 parts 4-(2-oxo-l-benzimidazolinyl)piperidine, 7.3 parts sodium carbonate, a few crystals of potassium iodide in 160 parts 4-methyl-2-pentanone is stirred and refluxed for 12 hours. After cooling the reaction mixture, 100 parts water is added. 

As mentioned earlier, stereochemistry is not of great concern in this book. However, certain mechanistic types will show specific stereochemical consequences when acting on chiral molecules. With this in mind, predict the product resulting from the E2 elimination of HBr when the shown isomer of 4-bromo-3-methyl-2-pentanone is treated with sodamide. Show all stereochemistry and explain your answer. 

Methyl cyclopropyl ketone has been prepared from ethyl aceto-acetate and ethylene bromide,6 and by the action of methyl-magnesium bromide on cyclopropyl cyanide.6-7 The procedure described for its preparation from 5-chloro-2-pentanone is similar to that of Zelinsky and Dengin.8 5-Chloro-2-pentanone has been prepared by a number of methods.9 The procedure given is essentially that of Boon 10 and of Forman.11 A similar procedure has been used for the preparation of the corresponding bromo-and iodoketones.10... 

C5H9Br 3-bromo-2-methyl-1 -butene 51872-48-1 376.08" 32.774 2 5067 C5H9CIO 1 -chloro-3-pentanone 32830-97-0 396.53 34.038 2... 

The total synthesis of (-)-denticulatin A, a polypropionate metabolite, was accomplished in the laboratory of F.E. Ziegler. To establish the absolute stereochemistry at C12, they utilized the Enders SAMP/RAMP hydrazone alkylation. To this end, the RAMP hydrazone of 3-pentanone was successfully alkylated with 1-bromo-2-methyl-2( )-pentene. Hydrolysis of the hydrazone under standard acidic conditions led to loss of the enantiomeric purity. This problem was avoided by using cupric acetate for the cleavage. 

HBr is led, with cooling in C02-acetone, into an a,/ -unsaturated aldehyde or ketone (which may be diluted with benzene or CS2) until HBr passes through. 4-Bromo-4-methyl-2-pentanone is thus obtained from mesityl oxide.205... 

Acetic acid Acetone Methyl acetate 2-Butanone Acetone 2-Butanone 4-Methyl-2-pentanone Isopropyl ether Toluene 2-Bromo-propane 2-Bromo-propane Isopropyl formate 2-Butanone... 

Ethanolic Na-ethoxide added slowly at 5-10 to a mixture of ethyl 2-bromo-3-methylpentanoate and thiophene-2-carboxaldehyde with stirring, whidi is continued 0.5 hr. at the same temp, and 3 hrs. while the mixture is allowed to warm to room temp., water added, stirred 3 hrs. in a steam bath, cooled to room temp., and dil. phosphoric acid added to bring the pH to 3, whereby COg-evolution occurs l-(2-thienyl)-3-methyl-2-pentanone. Y 82%. F. e. s. J.D. Belcher, Jr., et al., J. Chem. Eng. Data 20, 206 (1975). 

Methyl-l-butene 3 Methyl-2-butanone 2-Pentanone 3 Pentanone Isobutyl formate l-Bromo-3-methylbutane l-Chloro-3-methylbutane... 

Isobutyl alcohol Ethyl sulfide Cyclopentane 2-Methyl-2-butene 3>Pentanone Isobutyl formate Methyl isobutyrate Propyl acetate l-Bromo-3-methylbutane... 

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