Methylenation ketones

J361 to over 5700, mw — 38000—600000, colorl, amorph or cryst, mp 240—250°, d (amorph) 1.04—1.065g/cc RI 1.59—1.60. Sol in CCI4, et benz, tol, et acet, benz, methyl et ketone, chlf, tetrahydrofuran, methyl isobutyl ketone, methylene chloride, o-dichlorobenz, py and cyclohexane. Styrene polymer can be prepd in many ways. The simplest procedure is that of heating the pure monomer. The general reaction can be represented as ... 

CINNOLINES AND QUINOXALINES Replacement of a methine in oxolinic acid (46) by nitrogen is apparently consistent with retention of antibacterial activity. One approach begins with reduction of nitroacetophenone 144 to afford the corresponding aminoketone (145). Treatment of this intermediate with nitrous acid leads to the diazonium salt the diazonium group condenses with the ketone methylene group (as its enol form) to lead to the cyclized product, cinnoline 147. Bromination proceeds at the position adjacent the enol grouping (148) ... 

Aliphatic ketone, methylene function reduction, 6-phenylhex-l-ene, 131-132 Alkane reduction alcohols, 12-27 allyl alcohols, 24 benzyl alcohols, 18-24 cyclopropylcarbinols, 17-18 metal-complexed alcohols,... 

Solvents used as nonreactive diluents include acetone, cellosolve, methyl ethyl ketone, methyl isobutyl ketone, methylene chloride, 1,1,1-trichloroethane, toluene, and xylene. Skin and eye irritation and, in higher concentrations, CNS depression and respiratory irritation may result ftom exposure to these solvents as diluents for epoxy resin... 

Ketone methylenation is usually effected with Ph,P=CH2, scarcely an atom-efficient process. Tu-Hsin Yan of National Chung-Hsing University reports (Organic Lett. 2004,6,4961) that reduction of CHjClj with Mg powder in the presence of TIC14 leads to a reagent that efficiently homologates even easily-enolizable ketones such as 1. The reagent also converts esters such as 3 to alkenes, albeit more slowly. 

Anhydroenneaheptitol pentanitrate has found no practical application, since the yield of alcohol is low owing to the fact that in the main acetone and formaldehyde react with one another to form polymers of vinyl methyl ketone (methylene acetone) CH2=CHCOCH3 (Muller [70]). 

Ketone methylenation with optical resolution. The key step in a synthesis of p-pnnnsinscnc (5), an important component of Ginseng, involves methylenation of the... 

Isobutyl methyl ketone Isopropyl alcohol Isopropyl nitrate Methanol Methoxyflurane Methyl ethyl ketone Methylene chloride Methylpentynol Paraldehyde... 

The combination of the chromatographic separation of enan-tiopure p-hydroxysulfoximine diastereomers and reductive elimination results in a method of ketone methylenation with optical resolution. The technique is illustrated in the synthesis of the ginseng sesquiterpene (—)-p-panasinsene and its enantiomer (eq 5). The addition of the enantiopure lithiosulfoximine to prochiral enones or the diastereoface selective addition to racemic enones results in the formation of two diastereomeric adducts. The hydroxy group in these adducts can be used to direct the Simmons-Smith cyclopropanation (eq 6 and eq 7). Catalytic osmylation of such adducts is directed by the anti effect of the hydroxy augmented by chelation by the methylimino group (eq 7). ... 

The above ketone methylenation is applicable to highly hindered ketones, which are usually inert to the Wittig method. For example, a highly hindered tricyclic ketone (norzizanone, 4a) undergoes the methylenylation to give zizaene (4b equation 4). A -Cholesten-3-one (5a) was also converted to the nonconjugated diene 3-methylene-A -cholestene (5b equation 5). ... 

In addition to the sulfoximines, Johnson has studied phosphinothioic amides as alkene precursors. This reagent has not achieved the popularity of the sulfoximines. It can be utilized for ketone methylen-ation with resolution, as well as for Ae synthesis of more highly substituted alkenes. Rigby has found that in the synthesis of guaianolides this reagent was effective where Peterson and Wittig reactions gave only p-elimination. ... 

Phenylthiomethyllithium was also used for ketone methylenation, - mainly in the case of hindered ketones which do not react with the usual Wittig reagent. This is a three-step sequence the reagent (2a) is added, then the resulting alcohol is acylated, and finally the exocyclic methylene is formed by reduction with lithium in ammonia (Scheme 17). 

Commonly used solvents include crude oil, light oil, benzene, and toluene. Less common but more selective solvents include chloroform, ethylacetate, isopropyl ether, tricresyl phosphate, methyl isobutyl ketone, methylene chloride, and butyl acetate. The selection of a solvent type for a specific extraction will be discussed under the section dealing with Equilibrium Considerations. ... 

The initial drum inventory conducted in 1979 found 17 051 drums on the surface, including 11 628 empty ones. The EPA analyzed the property and creek and found 140 chemical substances. The chemicals found most often and in the highest concentrations were xylene, methyl ethyl ketone, methylene chloride, acetone, phthalates, anthracene, toluene, fluoranthene, alkyl benzene, vinyl chloride, dichloroethylene, and aliphatic acids. Polychlorobi-phenyls were detected in low concentrations and several metals including barium, zinc, copper, strontium, magnesium, and chromium were detected in concentrations exceeding background levels. 

Esters -> vinyl ethers. The original publication (8, 83-84) mentioned that ethyl acetate reacts with 1 to give ethyl isopropenyl ether. More recent work1 has shown that this conversion of esters to vinyl ethers is general and proceeds in high yields. The reaclion rate is dramatically increased by the presence of donor ligands (THF, C,11SN). The solvent is benzene or toluene. Ketone methylenation is possible, and actually Ihc rate is lour times that of ester methylenation. Isolated yields are cited in the examples. 

Methyl ethyl ketone Methyl isobutyl ketone Methylene dianiline Mirex... 

In summary, the Coll(bpy)2 /HOOH/(4 1 MeCN/py) system forms a reactive intermediate (20) that selectively ketonizes methylenic carbon, and as such is closely similar to the intermediate of the Fe KPA)2/HOOH/(2 1 py/HOAc) system.36 The ability of FeP(DPAH)2 to activate O2 to an intermediate that has the same unique selectivity for hydrocarbon ketonization is further support for a common stabilized-dioxygen reactive complex (see Chapter 6), Several cobalt-dioxygen complexes exhibit oxygenase reactivity with organic substrates, 0,4l which is consistent with the dioxygen formulation for species 20. 

Most proprietary cleaning solvents do not attack it unless the components are heavily stressed known exceptions are esters, ketones, methylene chloride and polar aromatic solvents. 

Tiffeneau-Demjanov ring-expansion of 6jff-acetoxy-5a-cholestan-3-one has been used to prepare the corresponding A-homo-4-ketone methylene insertion with diazomethane led to A-bis- and -tris-homocholestanones as the only isolated products. 

Cyclopropyl ketones. Methylene groups attached to a cyclopropane ring are nidized. 

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