Methyl levulinate

In his cephalosporin synthesis methyl levulinate was condensed with cysteine in acidic medium to give a bicyclic thiazolidine. One may rationalize the regioselective formation of this bicycle with the assumption that in the acidic reaction mixture the tMoI group is the only nucleophile present, which can add to the ketone. Intramolecular amide formation from the methyl ester and acid-catalyzed dehydration would then lead to the thiazolidine and y-lactam rings. The stereochemistry at the carboxylic acid a-... 

Methyl levulinate 679 condenses with silylated y9-alanine 680 in the presence of catalytic amounts of TsOH-H20 to give hexamethyldisiloxane 7 and the Schiff-base 681, whose O-trimethylsilyl groups are saponified by water (derived from TsOH H2O) to give, via 682, the intermediate enamine 683. Subsequent condensation of 683 with the Schiff base 681 affords, via 684, and subsequent saponification, a 4 1 mixture of olefins 685 and 686 [201, 202] (Scheme 5.64). 

Most early publications on bacterial polysaccharides were concerned with impure products and poorly-described organisms. Many more recent papers are of limited value also, due to low yields, lack of characterization of products and arbitrary interpretations of data. Low yields of methylated polysaccharides may be due to degradation of the bacterial polysaccharide during methylation, or to degradation of the hydrolytic products of the methylated polysaccharide (to form methyl levulinate, etc.46). The great importance of (a) complete methylation of polysaccharide products prior to structural determination by hydrolysis and (6) quantitative identification of the hydrolytic products, has been emphasized previously. Other difficulties in end group analysis have been discussed recently.7... 

Kl=acetophenone,K2=n-propyl pyruvate (CPl3C0C02-n-Pr),K3=i-butyl levulinate (CH3COCH2CH2C02- -Bu),K4=f-BuCOCH3,K5=3-MeOPhCOCH3,K6=2-py-ridyl methyl ketone, K7=l-tetralone, K8=l-acetylnaphthalene,K9=2-acetylnaphthalene,K10=ethyl levulinate,Kll=2-octanone,K12=2-phenylcyclohexanone, K13=3-pyridyl methyl ketone, K14=Me2HSiOCH2COCH3,K15=Me2HSiOCH2COPh,K16=l-cyclohexenyl methyl ketone, K17=ethyl pyruvate, K18=2,2-dimethyl-acetylacetonate,K19=methyl levulinate, K20=3,3-dimethyl-pentane-2,4-dione, K21=2-nonanone,K22=PhCOCH2Cl. 

The method has been extended to a synthesis of the 1,4-diketone (2) from the ethylene ketal of methyl levulinate (1). The diketone was cyclized by base to dihydrojasmone (3). The overall yield of (3) from (1) was 49.5%. The process is shown in scheme II. ... 

This chapter provides an industrial perspective on several oxidation routes to new bio-based molecules. In particular, it focuses on the use of Co/Mn/Br catalyst systems in air oxidations, based on the Amoco Mid-Century catalyst system used for / r -xylene oxidation (also see Chapter 4), as an efficient methodology for the conversion of 5-(hydroxymethyl)furfural (HMF) and 5-(methoxymethyl)furfural (MMF) to 2,5-furandicarboxylic acid (FDCA) in Avantium s YXY process. In addition, other less-studied conversions, such as methyl levulinate (ML) to succinic acid (SA), lignin to a variety of aromatic and phenolic carboxylic acids, are discussed as well. 

Indometacin was discovered at the beginning of the 1960s by the Merck Sharp Dohme company, and was approved by the FDA in 1965 for the United States market. The industrial synthesis involves a Fischer indole synthesis of 4-meth-oxyphenylhydrazine with methyl levulinate. The charme of this route is that the indole synthesis is carried out stepwise, and that 4-chlorobenzoyl chloride is added at the hydrazone stage. In this way, the methyl ester of indometacin is produced, which requires only hydrolysis to generate the active material. 

Tfflninaga K-I, Mori A, Fuknshima Y, Shimada S, Sato K (2011) Mixed-acid systems for the catalytic synthesis of methyl levulinate from cellulose. Green Chem 13(4) 810-812... 

An attempt to convert methyl levulinate to vinyl levulinate was unsuccessful (Figure 2). Heating methyl ester with vinyl acetate in acidic mercuric acetate gave a-angelica lactone as the major product rather than the vinyl ester. Vinyl levulinate was previously prepared by the mercuric ion-catalyzed reaction of levulinic acid with vinyl acetate (id), so this older preparation will be used for future studies. a-Angelica lactone can also be prepared by dehydration of the acid without the use of vinyl acetate (/ 7). 

Ethyl levulinate Methyl levulinate Ethyl levulinate Ethyl levulinate... 

A mixture of palmitaldehyde 2,4-dinitrophenylhydrazone, levulinic acid, and BFg-methanol reagent (or methanolic 10%-HCl) refluxed 45 min. at 85°, cooled to 0°, 90%-methanolic 5 N NaOH added, and again refluxed 20 min. to saponify the methyl levulinate palmitaldehyde dimethyl acetal. Y 84%. Also with acetone (Y 77%) in place of levulinic acid s. V. Mahadevan, F. Phillips, and W. O. Lundberg, J. Lipid Research 6, 434 (1965). 

A synthesis of dihydrojasmone (493) and cis-jasmone (486) has been reported which centres on the formation of 1,4-diketones.Compound (492) was derived from acyloin condensation of methyl levulinate ethylene acetal in the presence of tri-methylchlorosilane the subsequent sequence is outlined in Scheme 27. By means of... 

Keywords Methyl levulinate, primary amines, isocyanides, azidotrimethylsilane, methanol, dichloromethane, room temperature, one-pot, two-step synthesis, Ugi reaction, 1,5-disubstituted tetrazoles, his-pyrrolidinone tetrazoles... 

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