Methyl tert-butyl ketone preparation

Tetrahydrobenzo[6]thiophen-4-one (103) may be prepared from y-(2-thienyl)butyric acid by cyclization with phosphoric acid854 or by Friedel-Crafts cyclization of the corresponding acid chloride.194, 355.358 j s 5-methyl,357 2-ethyl,194 2-isopropyl,358 2- and 3-tert-butyl,359 2,3-dimethyl,360 2-ethyl-3-methyl,360 and 2-bromo 354 derivatives and diethyl 4,5,6,7-tetrahydrobenzo[6]thiophene-4,5-di-carboxylate861 may be prepared similarly. 4,5,6,7-Tetrahydrobenzo-[6]thiophen-7-one (104)357 362,863 and its 5- and 6-methyl 357 and 2-chloro 362 derivatives are obtained from the appropriately substituted y-(3-thienyl)butyric acid, A recent patent 364 describes the vapor phase cyclization of y-(2-thienyl)butyric acid to 103. Ketones (103 and 104) are useful intermediates for the synthesis of 4- and 7-substituted benzo[6]thiophenes, respectively their reactions are discussed in Section VI, B, 4. 

The situation is similar with cyclic boronates, which are prepared by the following procedure. Steroid (10 pmol) and the respective substituted boric acid (10 jumol) are dissolved in ethyl acetate (1 ml) and the mixture is allowed to stand for 5 min at room temperature. Under these conditions, 17,20-diols, 20,21-diols and 17,20,21-triols are converted completely into boronates. Cyclic boronate was mainly produced from 17,21-dihydroxy-20-ketone, but side-products also appeared, the formation of which could be suppressed by adding a 10% excess of the reagent [387—389]. Different substituents on the boron atom, such as methyl, n-butyl, tert.-butyl, cyclohexyl and phenyl, are interesting from the viewpoint of GC—MS application. They are further suitable for converting isolated hydroxyl groups into TMS or acetyl derivatives. 

Oxidative cleavage of open-chain ketones or alcohols is seldom a useful preparative procedure, not because these compounds do not undergo oxidation (they do, except for diaryl ketones), but because the result is generally a hopeless mixture. Aryl methyl ketones, such as acetophenone, however, are readily oxidized to aryl carboxylic acids with Re207 and 70% aqueous tert-butyl hydroperoxide. Oxygen with a mixture of manganese and cobalt catalysts give similar oxidative... 

Although not of much real preparative interest, radical decarbonylation has been observed with a large number of aldehydes and ketones at high temperatures and/or under ultraviolet irradiation or in the presence of peroxides. For example, carbon monoxide is eliminated in 90% yield when 3-methyl-3-phenylbutanal is heated for five hours at 130° in the presence of di-tert-butyl peroxide fractionation of the residue then affords 70% of a 1 1 mixture of terr-butyl- and isobutyl-benzene, so that the / ,/ -dimethyl-phenethyl radical formed on elimination of carbon monoxide from the C6H5C(CH3)2CH2CO— radical must be assumed to have partially rearranged.66... 

Graft/Blend Polymers. These polymers were prepared by dissolving PVC in either methyl ethyl ketone or tetrahydrofuran, followed by the appropriate 2-ethylhexyl acrylate/acrylonitrile monomer charge and the free radial initiator, e.g., Lupersol 11 (tert-butyl peroxypivalate). This solution was then heated to 50°-70°C in 4-oz bottles, 2-1. glass reactors, or larger glass-lined autoclaves. Polymerization times were normally 12-16 hrs a conversion check was then made, and, if conversion was complete, films were cast from the polymer solution. 

The starting material, methoxytetralin (293), was converted into the a,(3-unsaturated ketone (294) by Birch reduction. The allene adduct (295) was prepared from ketone 294 and was then rearranged to the hydroxyl ketone (298) via intermediates 296 and 297. Compound 298 was methylated with sodium hydride and methyliodide to give the methoxyketone (299) in quanitative yield. Compound 299 was rearranged to 300 by refluxing with tert-butyl perbenzoate and cuprous bromide in absolute... 

With a high-temperature initiator such as di-tert-butyl peroxide, copolymers of 1-octene with allyl propionate or allyl butyrate have been prepared in sealed tubes. The reaction conditions included methyl ethyl ketone as a solvent, 0.05% di-tert-butyl peroxide heated in sealed ampoules at 200°C for 4 hr. The molecular weights of the product were in the range of 600 200 [62]. 

The Grignard reagent prepared from (-f-)-l-chloro-2-methyl-butane reduces a tert-butyl, phenyl, or cyclohexyl ketone to unequal amounts of the corresponding enantiomeric secondary alcohols (Fig. 13). The per cent asymmetric reduction obtained with several of the above types of ketones is shown in Table I. 

In many cases, azobis(isobutyronitrile) (AIBN) is employed as radical initiator. The polymerization conditions, in particular solvent, depend mainly on both, solubility of the starting sf monomers and choice of comonomer. To give just a few examples, copolymers of dodecafluoroheptyl methacrylate with methacrylic acid could be synthesized in dioxane due to the solubilizing effect of methacrylic acid [66], copolymers of sfMA-H2F8 and sfMA-H2F4 with styrene could be prepared in toluene [35], and copolymerizations of i/methacrylates with butyl acrylate, hydroxy-butyl acrylate, and styrene were performed using tert-butyl peroxyacetate as initiator in methyl amyl ketone [31]. 

Preparation by selective methylation of 5-tert-butyl-2,4-di-hydroxybenzophenone with dimethyl sulfate in refluxing methyl ethyl ketone for 7 h in the presence of potassium carbonate (81%) [835]. 

Preparation by demethylation of 3,3, 5,5 -tetra-tert-butyl-4,4 -dimethoxy-benzophenone (SM) by means of sodium thioethoxide, under nitrogen, in refluxing N,N-dimethylformamide for 15 h (95%). SM was obtained by a two-step synthesis at first, total methylation of 3,3, 5,5 -tetra-tert-butyl-4,4 -dihydroxydiphenyl-methane with methyl iodide in the presence of sodium hydride, under nitrogen, in refluxing tetrahydrofuran for 2 h. Then, by adding a solution of chromium trioxide in dilute sulfuric acid to an acetonic solution of the dimethyl ether previously formed (82%) and stirring at r.t. for 70 h, one obtains the expected ketone SM (86%) [334]. 

Yamamoto has recently described a novel catalytic, asymmetric aldol addition reaction of enol stannanes 19 and 21 with aldehydes (Eqs. 8B2.6 and 8B2.7) [14]. The stannyl ketones are prepared solvent-free by treatment of the corresponding enol acetates with tributyltin methoxide. Although, in general, these enolates are known to exist as mixtures of C- and 0-bound tautomers, it is reported that the mixture may be utilized in the catalytic process. The complexes Yamamoto utilized in this unprecedented process are noteworthy in their novelty as catalysts for catalytic C-C bond-forming reactions. The active complex is generated upon treatment of Ag(OTf) with (U)-BINAP in THE Under optimal conditions, 10 mol % catalyst 20 effects the addition of enol stannanes with benzaldehyde, hydrocinnamaldehyde, or cinnamaldehyde to give the adducts of acetone, tert-butyl methyl ketone (pinacolone), and acetophenone in good yields and 41-95% ee (Table 8B2.3). 

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