Mesityl oxide, addition

It la of Interest to note that the preparation of dimethyldihydroresorcinol (also named dlmedone and methone Section VII, 15) involves an initial Dchael addition to mesityl oxide, followed by an internal Claiaen condensation. 

Primary amines form Schiff bases, (CH3 )2C=NR. Ammonia induces an aldol condensation followed by 1,4-addition of ammonia to produce diacetone amine (from mesityl oxide), 4-amino-4-methyl-2-pentanone [625-04-7] (CH2)2C(NH2)CH2COCH2, and triacetone amine (from phorone),... 

In addition to generating malodorous sulfur dioxide [7446-09-5], the acetone formed can undergo further condensation in the acidic medium to generate mesityl oxide [141-79-7], (CH2)2C=CHCOCH2, and higher products. 

V,7V-dimethylaminopyridme provides l-(2-methoxycarbonyl)ethoxy- (40,69%) and l-(2-methoxycarbonyl-l-methyl)ethoxytryptamine (41, 72%), respectively (Scheme 4). The conjugate addition to mesityl oxide proceeds successfully as well, giving iVb-acetyl-1-(1, l-dimethyl-3-oxo)butoxytryptamine (42,49%), while the reaction with methyl 3-methylcrotonate affords 43 in a miserable yield (1.6%). Addition to acrolein results in failure, and 44 is not yet obtained. 

Compound 68 can also be obtained by an acid-catalyzed cyclization of 42, which was prepared by the Michael addition reaction of 39 to mesityl oxide as shown in Section IV.A. As for the product 69, the presence of the tosyloxy group at the 5 position instead of the 6 position is determined, utilizing the anisotropy effect of the 1-acetyl group to the C-7 proton, by comparing its H NMR spectrum with that of 70, obtained in 69% yield by the treatment of 69 with NaH and AcCl. 

Photolysis of complex (189), R = mesityl, causes geometric isomerization to (190), with the structure (190) established by single-crystal diffraction studies.354 Reaction of Ph2P(CH2)2Si(Me)2-Si(Me)2(CH2)2PPh2 with t/Y// ,v-[Ir(PPh3)2(CO)Cl] yields complex (191) via an oxidative addition reaction to the Si-Si linkage.355... 

The first method has been used with haloaryl,1639-1643 urt/m-nitrophenyl,1644 mesityl,255 or ylidegold(I)1645-1648 complexes, which are sufficiently stable to undergo the oxidative addition without cleavage of the gold-carbon bond, an example can be seen in Equation (11) ... 

The reaction mechanism is shown in Figure 4 and is adapted from work by Fiego et al. [9] on the acid catalysed condensation of acetone by basic molecular sieves. The scheme has been modified to include the hydrogenation of mesityl oxide to MIBK. The scheme begins with the self-condensation of acetone to form diacetone alcohol as the primary product. The dehydration of DAA forms mesityl oxide, which undergoes addition of an addition acetone to form phorone that then can cyclise, via a 1,6-Michael addition to produce isophorone. Alternatively, the mesityl oxide can hydrogenate to form MIBK. 

Use of the same benzyl(methyl)phenylphosphine and DIOP rhodium(I) catalysts with ,/3-unsaturated carbonyls has led to some interesting selectivity patterns (297, 298). Dihydrosilanes undergo 1,2-addition at the carbonyl of substrates such as 2-methylcyclohexenone, mesityl oxide,... 

In a 2-1. four-necked flask (or a three-necked flask with a Y-tube connector) equipped with a stirrer, a reflux condenser, a dropping funnel, and a thermometer extending nearly, to the bottom of the flask is placed 550 ml. (595 g., 5.83 moles) of acetic anhydride which is cooled to 0° with an ice-salt bath. Then 180 ml. (300 g., 2.09 moles) of a 70% solution of perchloric acid is added with stirring at a rate such that the temperature does not rise above 8° (Note 1). This step takes about 3 hours. The mixture is continually cooled and stirred, and 240 ml. (204 g., 2.09 moles) of mesityl oxide is then added slowly. The slow addition of 370 ml. (400 g., 3.92 moles) of acetic anhydride follows. The ice bath is then replaced by a water bath the temperature of the reaction mixture will usually rise to 50-70° because of the heat liberated by the exothermic reaction, and the reaction mixture will turn dark. The reaction mixture is heated on a steam bath for 15 minutes to complete the reaction, and the mixture is then allowed to cool and stand at room temperature for 2 hours. The crystals,... 

Fig. 7 Mobility-shift assay for the determination of dissociation constant of the complex between anti-DNP rat monoclonal IgG21) antibody and charged ligands that contained the A-dinitrophenyl group. Mesityl oxide (MO) served as EOF marker, bovine carbonic anhydrase (CAB) and bovine a-lactalbumin (LA) as internal references. The DNP ligands with a charge of —1 (A) und —9 (B), respectively, were used as additives to the running buffer. (Reprinted with permission from Ref. 30. Copyright 1995 American Chemical Society.)...

In respect of cycloreversion, cyclobutane-fused fullerenes derived from acyclic enones [342] are less stable than their bycycKc equivalents (e.g. 293, Scheme 4.55). For the addition of mesityl oxide the equilibrium constant is so small that a 1000-fold excess of the enone is necessary to complete the reaction. The product of 302 is more stable and requires only a 100-fold excess of the enone. Reaction of 302... 

To 0.2 mole of an olefin dissolved in 30 ml of glacial acetic acid is added 19.5 gm (0.3 mole) of sodium azide in 75 ml of water. The addition to acrolein and jf -nitrostyrene underwent rapid addition, requiring cooling with an ice-salt bath and slow addition of the sodium azide. Addition to methyl acrylate, acrylic acid, and acrylonitrile required 1-3 days at room temperature, a-vinyl pyridine and mesityl oxide required heating for 24 hr on a steam bath. Other olefins underwent no reaction even after 7 days of heating and were recovered unchanged. 

The preparation of iV-nitroso-/5-alkylaminoisobutyl ketones is of particular interest as a method for preparing the intermediates for the diazoalkane synthesis. The preparation of these compounds is based on the addition of a primary amine to mesityl oxide to give a secondary amino ketone which is then nitrosated (see Volume I, Chapter 15, Section 2A,g). This preparation uses an... 

The electrochemical analysis allowed the determination of kinetic constants for this reaction46. Thus, in the presence of bromobenzene, the rate constant for the oxidative addition was found to be equal to about 70 M 1 s 1. The a-arylnickel complexes are unstable, except those obtained from o-tolyl or mesityl bromide as starting substrates. In these particular cases, the arylnickel complexes can be prepared by electrolysis from an ArBr/NiBr2(bpy) equimolar ratio. However, the exhaustive electrolysis of an aromatic iodide in the presence of ZnBr2, in DMF and at —1.4 V/SCE, leads to the corresponding arylzinc compound but the yield remains low (<20%). Indeed, the aryl iodide is mainly converted to ArH according to, very likely, a radical process (Scheme 11). 

Exercise 17-23 Aldol additions also occur in the presence of acidic catalysts. For example, 2-propanone with dry hydrogen chloride slowly yields (CH3)2C=CHCOCH3 (mesityl oxide) and (CH3)2C=CHCOCH=C(CH3)2 (phorone). Write mechanisms for the formation of these products, giving particular attention to the way in which the new carbon-carbon bonds are formed. 

In addition to conjugated dienes, cyanocobalt catalysts also hydrogenate the C=C bond of activated alkenes.52 Carvene, mesityl oxide, 2-cyclohexenone, benzalacetone and an androstenone derivative were reduced in this way.53... 

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