L-Methoxy-2-butanone

The comparison between the cycloaddition behavior of simple diazoketones and of ethyl diazopyruvate 56 towards the same olefin underlines the crucial influence of the ethoxycarbonyl group attached to the carbonyl function. This becomes once again evident when COOEt is replaced by an acetal function, such as in l-diazo-3,3-di-methoxy-2-butanone 86 with enol ethers and acetates, cyclopropanes rather than dihydrofurans are now obtained 113). ... 

Material accountability (the sum of recovered chloropinacolone, methyl pivaloyl acetate, and pinacolone) with the active Pd monophosphine and carbene complexes was in the range of 92-99% without accounting for impurities present in the starting chloropinacolone. A GC-MS examination of several product mixtures was undertaken to see if there were any additional, unanticipated by-products. The only additional material identified was a-methoxy pinacolone (l-methoxy-3,3-dimethyl-2-butanone). This compound was formed by methanolysis of the starting a-chloropinacolone and appears to be formed by a mixture of catalyzed and uncatalyzed processes Since this product was not anticipated, it was not quantified but represents the majority of, if not the only, remaining volatile product. No attempt was made to determine the presence of any quaternary ammonium salt formed by similar alkylation of the amine base by a-chloropinacolone. 

The synthesis of lupeol starts with the cyclization of 6-methoxy-p-methyl-a-tetralone 28 with 4-7V 7V -dimethylamino-2-butanone methiodide in the presence of potassium /-butanolate to l,9,10,10a-tetrahydro-7-methoxy-3(2//)-phenanthrone 27. Reduction with sodium borohydride and subsequent hydrogenation of the enone CC double bond in the presence of palladium and strontium carbonate as slightly deactivated catalyst gives the oetahydrophenanthrol 26. Partial reduction of the benzenoid ring to the enone is aceomplished by lithium in liquid ammonia. The enone is derivatized to the benzoate 25 in order to protect the hydroxy group prior to the subsequent synthetic steps. 

Methoxy-3(5)-methylpyrazine 4-p-Methoxyphenyl-2-butanone 1-(4-Methoxyphenyl)-4-methyl-1-penten-3-one 1-(p-Methoxyphenyl)-l -penten-3-one 1 -(p-Methoxyphenyl)-2-propanone... 

CjoHaNiO) 2-AthyI-2- iieny 1-1 -[4-methoxy-ghen -butanon-(l -8emicarbazon... 

Mallotojaponol. l-[3-[(3-Acetyl-2,4-dihydroxy-6-methoxy-5-methylphenyl) methylJ-5-(2,3-dihydroxy-3-methylbutyl)-2,4,6-trihydroxyphenyl]ethanone, 1643 Mallotolerin. l-[3-[(3-Acetyl-2,4-dihydroxy-6-methoxy-5-methylphenyl)methyl]-2,4,6-trihydroxy-5-(2-hydroxy-3-methyl-3-butenyl)phenyl]-l-butanone, 1606,1644 Mallotophenone. l,l -[Methylenebis(2,6-dihydroxy-4-methoxy-5-methyl-3,l-phenylene)]bis-ethanone, 1604... 

Margaspidin BP. l-[3-[[2,4-Dihydroxy-6-methoxy-5-methyl-3-( 1-oxopropyl) phenyl]methyl]-2,4,6-trihydroxy-5-methylphenyl]-l-butanone, 2144 Margaspidin PB. l-[2,6-Dihydroxy-4-methoxy-3-methyl-5-[12,4,6-trihydroxy-3-methyl-5-( 1 -oxopropyljphenylJmethylJphenylJ-l-butanone, 2144 Margaspidin PP. l-[3-[[2,4-Dihydroxy-6-methoxy-5-methyl-3-( 1-oxopropyl) phenyl]methyl]-2,4,6-trihydroxy-5-methylphenyl]-l-propanone, 2124 Mesuol. 5,7-Dihydroxy-8-(3-methyl-2-butenyl)-6-(2-methyl-l-oxopropyl)-4-phenyl-2H-l-benzopyran-2-one, 2081... 

The first stage of the synthesis, the preparation of the unsaturated cyclic ketone (140) is illustrated in Scheme 94. Here the starting material is 5-methoxy-2-tetralone (51), which was obtained in two stages from 2, 5-dihydroxynaphthalene with an over-all yield of 73% (Chapter HI, Scheme 56). Condensation of the tetralone (51) with l-diethylamino-3-pentanone methio-dide led to a mixture of the A - and A -tricyclic ketones (138). The next stage, the formation of ring A, can be carried out both with methyl vinyl ketone (yield 75%) and with l-diethylamino-3-butanone methiodide (yield 64%). The isolation of the tricyclic ketones (138) was not necessary, and by successively condensing the tetralone (51) with the diethylaminopen-tanone methiodide and methyl vinyl ketone it was possible to obtain the tetracyclic product (140) with an over-all yield of 34% [915, 916]. 

Dipyridyl-a-glyoxime, in D-01063 3,3 -(l,2-Ethanediyldinitrilo)bis-2-butanone Dioxime, in E-00035 A, A -Ethylenebis(4-methoxy-1,2-benzoquinone 2-imine) Dioxime, in E-00076... 

A soln. of p-nitrosodimethylaniline in ethanol mixed with aq. NaCN, warmed to 40 , poured on the pyridinium salt prepared from l-chloro-4-(2,3,4,4 -tetra-methoxy"5-bromo-6-diphenylyl) -2-butanone whereupon the product precipitates a- (p-dimethylaminophenylimino) -y -keto-(5-(2,3,4,4 -tetramethoxy-5-... 

The most recent, and probably most elegant, process for the asymmetric synthesis of (+)-estrone appHes a tandem Claisen rearrangement and intramolecular ene-reaction (Eig. 23). StereochemicaHy pure (185) is synthesized from (2R)-l,2-0-isopropyhdene-3-butanone in an overall yield of 86% in four chemical steps. Heating a toluene solution of (185), enol ether (187), and 2,6-dimethylphenol to 180°C in a sealed tube for 60 h produces (190) in 76% yield after purification. Ozonolysis of (190) followed by base-catalyzed epimerization of the C8a-hydrogen to a C8P-hydrogen (again similar to conversion of (175) to (176)) produces (184) in 46% yield from (190). Aldehyde (184) was converted to 9,11-dehydroestrone methyl ether (177) as discussed above. The overall yield of 9,11-dehydroestrone methyl ether (177) was 17% in five steps from 6-methoxy-l-tetralone (186) and (185) (201). 

Cyclic acetals of ketoses are prepared most commonly from acetone or benzaldehyde formaldehyde, acetaldehyde, butanone, and cyclohexanone have been used occasionally. These carbonyl reagents are frequently used directly, although such derivatives as 2,2-di-methoxy- or 2,2-diethoxy -propane (acetone dialkyl acetals), or l,l-dimethoxyethane (acetaldehyde diethyl acetal), are often employed in experiments in which intermediate acetals are of interest,or in which the presence of water in the reaction mixture adversely affects the yield of products. A polymeric form of an aldehyde is the reagent to be preferred whenever the monomer is volatile for example, acetaldehyde is often used in the form of a trimer, paraldehyde, and formaldehyde is employed as formalin solution, as paraformaldehyde, or as polyoxymethylene. An excess of the carbonyl reagent is generally used as the solvent, and the condensation is usually effected at room temperature. 

I-Me ether [159686-24-5]. I- 3-Ethyl-2,4-dihydroxy-6-methoxyphenyl)-1-butanone. 2-Ethyl-5-methoxy-4- l-oxobutyl)- , 3-benzene diol C13H18O4 M 238.283 Metab. of Phoma etheridgei. Solid. 

Acetyl-2,6-dihydroxy-4-methoxy-5-methylphenyl)methyl] -5- [ [2,6-dihydroxy-4-methoxy-3-methyl-5-(2-methyl-l-oxopropyl)phenyl]methyl]-2,4,6-trihydroxyphenyl]-2-methyl-1 -butanone, 2166... 

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