Ester-mesityl

Unsymmetrically substituted unsaturated NHC catalysts (silyl ether-mesityl 34 [86,87], perfluoroalkyl-mesityl 35 [86], ester-mesityl 36 [88]) can catalyze the RCM of dienes, however, with lower yields than those obtained with the parent catalyst 2 (Fig. 7). Subsequently, Blechert et al. reported the synthesis of alkyl-mesityl saturated NHC complexes 37 and 38. These catalysts show a generally lower reactivity than the corresponding symmetric catalysts 3 and 15 in RCM and CM [89]. 

Functional groups tend to deactivate the catalysts but reduction can be achieved by working at 100 atm H2 and 20°C under these conditions, diolefins (e.g., vinylcyclohexene, 1,5-hexadiene) are reduced to paraffins (ethylcyclohexane, hexane), and unsaturated ketones or esters (mesityl oxide, vinyl acetate) are reduced (to methyl (isobutyl) ketone or ethyl acetate). 

Malonic acid, amino-, diethyl ester, HYDROCHLORIDE, 40, 24 Malonic acid, bts(hydroxymethyl)-, DIETHYL ETHER, 40, 27 Malonitrile, condensation with tetra-cyanoethylene, 41, 99 2-Mercaptopyrimidine, 43, 6S hydrochloride of, 43, 68 Mercuric oxide in preparation of bromo-cyclopropane, 43, 9 Mesityl isocyanide, 41,103 5-Methallyl-l,2,3,4,5-pentachlorocyclo-pentadiene, 43, 92 Methane, dimesityl-, 43, 57 Methanesiileinyl chloride, 40, 62 Methanesulfonic acid, solvent for making peroxybenzoic acid from benzoic acid, 43, 93... 

Although menthyl esters, especially 19, are most often used to prepare sulfoxides, esters derived from optically active alcohols other than menthol have been prepared . Ridley and Smal prepared arenesulfmic esters of 1,2 5,6-di-O-cyclohexylidene-a-D-glucofuranose. Unfortunately, these diastereomers were oils, except for the mesityl derivative, with the major epimer having configuration R at sulfur and so they offered no advantage over the menthyl esters. Separation of the epimers by chromatography failed. 

Anthryl, 1-naphthyl, mesityl, and 4-quinolyl groups in 37h-k promote C/C aryl shift (see Table 2) their proclivity to migrate is far greater than expected from the electronic influence of the x-systems. This is presumably due to the intermediacy of spiro-linked benzenium betaines 30 31 , occurring in place of the carbenes otherwise encountered. The formation of phosphinic esters 42h-k is partly or completely suppressed 30). 

Amines, thiols, eOH (p. 226), etc., will also add to the 0-carbon atom of 0-unsaturated carbonyl compounds and esters, but the most important reactions of C=C—C=0 systems are in Michael reactions with carbanions reactions in which carbon-carbon bonds are formed. A good example is the synthesis of l,l-dimethylcyclohexan-3,5-dione (dimedone, 100) starting from 2-methylpent-2-ene-4-one (mesityl oxide, 101) and the carbanion 0CH(CO2Et)2 ... 

The starting benzothiazole carboxylic ester 387 was subjected to a Anamination by using mesityl hydroxylamine to give an A -amino salt 388, which was treated with a tertiary amine to give the deprotonated intermediate 389. This species when reacted with phenylisocyanate yielded the final product 390 in moderate yield <2001JOC8528>. 

Synthetic methods. / / -Dimethylglutaric acid (prepared from mesityl oxide) was converted into the di-silver salt, which, by an improvement of the method of Windaus and Klanhardt, was converted into / / -dimethyl-y-butyrolactone. The latter on treatment with constant-boiling hydrobromic and sulphuric acid gave y bromo /i/ dimethylbutyric acid which readily gave its ethyl ester. The pure fluoro ester was obtained from this by heating with silver fluoride, although the yield was low. 

With the exception of the parent compounds, where the Michael adducts are isolated, acrylic esters [see, e.g. 6,7,31,105,111 ] and nitriles [6,7], and vinyl ketones [26, 113, 115] generally yield the cyclopropanes (Table 7.6) under the standard Makosza conditions with chloroform. Mesityl oxide produces a trichlorocyclopropy-lpropyne in low yield (10%) [7]. When there is no substituent, other than the electron-withdrawing group at the a-position of the alkene, further reaction occurs with the trichloromethyl anion to produce spiro systems (35-48%) (Scheme 7.12) [7, 31]. Under analogous conditions, similar spiro systems are formed with a,p-unsaturated steroidal ketones [39]. Generally, bromoform produces cyclo adducts with all alkenes. Vinyl sulphones are converted into the dichlorocyclopropane derivatives either directly or via the base-catalysed cyclization of intermediate trichloromethyl deriva-... 

Indenopyrene, see Indeno[l,2,3-crf pyrene l//-Indole, see Indole Indolene, see Indoline Inexit, see Lindane Inhibisol, see 1,1,1-Trichloroethane Insecticide 497, see Dieldrin Insecticide 4049, see Malathion Insectophene, see a-Endosulfan, p-Endosulfan Intox 8, see Chlordane Inverton 245, see 2,4,5-T lodomethane, see Methyl iodide IP, see Indeno[l,2,3-crf pyrene IP3, see Isoamyl alcohol Ipaner, see 2,4-D IPE, see Isopropyl ether IPH, see Phenol Ipersan, see Trifluralin Iphanon, see Camphor Isceon 11, see Trichlorofluoromethane Isceon 122, see Dichlorodifluoromethane Iscobrome, see Methyl bromide Iscobrome D, see Ethylene dibromide Isoacetophorone, see Isophorone a-Isoamylene, see 3-Methyl-l-butene Isoamyl ethanoate, see Isoamyl acetate Isoamylhydride, see 2-Methylbutane Isoamylol, see Isoamyl alcohol Isobac, see 2,4-Dichlorophenol Isobenzofuran-l,3-dione, see Phthalic anhydride 1,3-Isobenzofurandione, see Phthalic anhydride IsoBuAc, see Isobutyl acetate IsoBuBz, see Isobutylbenzene Isobutane, see 2-Methylpropane Isobutanol, see Isobutyl alcohol Isobutene, see 2-Methylpropene Isobutenyl methyl ketone, see Mesityl oxide Isobutyl carbinol, see Isoamyl alcohol Isobutylene, see 2-Methylpropene Isobutylethylene, see 4-Methyl-l-pentene Isobutyl ketone, see Diisobutyl ketone Isobutyl methyl ketone, see 4-Methyl-2-pentanone Isobutyltrimethylmethane, see 2,2,4-Trimethylpentane Isocumene, see Propylbenzene Isocyanatomethane, see Methyl isocyanate Isocyanic acid, methyl ester, see Methyl isocyanate Isocyanic acid, methylphenylene ester, see 2,4-Toluene-diisocyanate... 

In a similar manner, introduction of the ferrocenyl group drastically changes the reactivity of the mesityl enol ester cation-radicals. These cation-radicals undergo a bond scission in solution according to the following equation (Mes = mesityl) ... 

Bode and co-workers further extended redox esterification to include carbon-carbon bond breaking of formyl-cyclopropanes [113]. Both esters and thioesters are formed in high yield and good enantioselectivities (Scheme 31). The M-mesityl substituted triazolium salt 191 proved to be the most efficient pre-catalyst providing complete suppression of the benzoin reaction. Electron-deficient substituents, such as phenyl ketone, readily provide ester formation. 

The Schneider group independently reported an asymmetric vinylogous Mannich reaction (Scheme 27) [47]. Addition of silyl dienolates 73 to A-PMP-protected imines 74 was promoted by phosphoric acid (R)-3g (5 mol%, R = Mes) with mesityl substituents to afford tra i -a,p-nnsatnrated 8-amino esters 75 in high yields (66-94%) together with good enantioselectivities (80-92% ee). 

In the presence of the hydrogen donor tri-Af-butyltin hydride, only hydroxamic ester 195 is formed and the reaction is presumed to involve N—O bond homolysis to give the resonance-stabilized Af-alkoxyamidyl radicals (198), which in the presence of BusSnH are reduced to hydroxamic ester according to Scheme 30. In the absence of BusSnH hydride, formation of esters probably involves alkoxyamidyl dimerization to hydrazines (199) as intermediates (see Section Vl.C, Scheme 34), although HERON reactions of 194 with production of methoxynitrene cannot be discounted. Mesityl radicals, formed by the... 

AUtylmagnesium halides and dialkyhnagnesium compounds are efficient metallating agents toward alkyl mesityl ketones such as Kohler s ketone (2,2-diphenylethyl 2,4,6-trimethylphenyl ketone) and hindered carboxylic esters such as f-butyl acetate. 

Frequently the basic conditions used cause the initial Michael adduct to undergo intramolecular transformations, as for example in the synthesis of dimedone (Expt 7.11). This involves a Michael reaction between mesityl oxide and diethyl malonate followed by an internal Claisen ester condensation. 

By using mesityl oxide and oxalic ester the condensation product is mesityl-oxide-oxalic ester ... 

---