From lactate ester

The levels of selectivity achieved in these reactions are amongst the highest reported for non-enzymatic acylative KR, and the scope of the method has been reviewed by Vedejs [40], as has its application in PKR [43]. The PBO catalysts 2a-c are prepared by a multi-step enantioselective synthesis from lactate esters [42, 44] and are air-sensitive hence, the reactions are generally run in de-oxygenated solvents. However, the air-stable tetrafluoroboric acid salts of these catalysts can also be employed with in-situ deprotonation by EtsN these conditions give results comparable with those obtained using the original protocol [45]. (For experimental details see Chapter 14.17.1). 

Alternatively, 689 is available from lactate esters 401 or 402 by partial reduction with diisobutylaluminum hydride at —78 °C [117,129,148]. Yields for this process typically range from 76-100%. 

Reaction of a metal lactate (such as silver lactate) with an alkyl haUde is a classic method of preparation of the ester, but it is too expensive to be of commercial relevance. Lactamide [2043-43-8] is another high yielding condensation product from lactic acid. It can be produced by aminolysis of dilactide or lactate ester such as methyl or ethyl lactate. 

Methylsuccinic acid has been prepared by the pyrolysis of tartaric acid from 1,2-dibromopropane or allyl halides by the action of potassium cyanide followed by hydrolysis by reduction of itaconic, citraconic, and mesaconic acids by hydrolysis of ketovalerolactonecarboxylic acid by decarboxylation of 1,1,2-propane tricarboxylic acid by oxidation of /3-methylcyclo-hexanone by fusion of gamboge with alkali by hydrog. nation and condensation of sodium lactate over nickel oxide from acetoacetic ester by successive alkylation with a methyl halide and a monohaloacetic ester by hydrolysis of oi-methyl-o -oxalosuccinic ester or a-methyl-a -acetosuccinic ester by action of hot, concentrated potassium hydroxide upon methyl-succinaldehyde dioxime from the ammonium salt of a-methyl-butyric acid by oxidation with. hydrogen peroxide from /9-methyllevulinic acid by oxidation with dilute nitric acid or hypobromite from /J-methyladipic acid and from the decomposition products of glyceric acid and pyruvic acid. The method described above is a modification of that of Higginbotham and Lapworth. ... 

Lactic acid is an important chemical that has wide applications in food, pharmaceutical, cosmetic, and chemical industries. There are increasing interests in production of lactate esters and biodegradable polylactic acid (PLA) from lactic acid. Lactate esters are a relatively new family of solvents with specific properties. They are considered safe and are biodegradable (1). In many situations they can replace toxic solvents. Their functions vary from that of intermediates in chemical reactions to solvents in ink formulations and cleaning applications (2). PLA has been widely used in medical implants, sutures, and drug-delivery systems because of its capacity to dissolve over time (3-5). PLA also can be used in products such as plant pots, disposable diapers, and textile fabrics. 

Fermentation-derived organic acids and their esters are potentially important chemical feedstocks for polymers and specialty polymers, but most significantly as alternative solvents for industrial and consumer applications. For example, lactate esters are derived from renewable carbohydrate raw materials such as cornstarch. They exhibit much lower toxicity compared with halogenated hydrocarbons and ethylene glycol ethers and are environmentally benign. Some studies suggested that lactate ester solvents have the potential of replacing petroleum-based solvents... 

Marshall, M.O., Knudsen, J. 1977. The specificity of 1-acyl-jn-glycerol 3-phosphate acyltrans-ferase in microsomal fractions from lactating cow mammary gland towards short, medium and long chain acyl-CoA esters. Biochim. Biophys. Acta 489, 236-241. 

In close relation to the work on acrylates derived from lactate, pantolactone and 2,5-disubstituted pyrrolidines (vide infra), A -acryloylproline benzyl ester (391) has t n studied as a chiral dienophile... 

Following the key finding of Helmchen [23], the bis-(S)-ethyl lactate ester of fumaric acid was prepared from fumaryl chloride, as illustrated in Scheme 2. Cycloaddition of this dienophile with cyclopentadiene to give (3) required some experimental modification in order to eliminate halogenated solvents. A survey of solvents and reaction conditions revealed that triethylamine as solvent allows both a reasonable reaction rate and high diastereomeric excess (d.e. = 93%) when the reaction is conveniently conducted at room temperature. 

BOM-protected lactaldehyde is available from lactate 282 via a two-step sequence involving reduction of the ester to alcohol 283 followed by Collins oxidation [100,186], or directly by partial reduction of the ester with diisobutylaluminum hydride in hexane at — 90 °C (80% yield) [100]. 

EE-protected lactaldehyde 606 is readily available from lactate 310 in two steps by reduction of the ester with lithium aluminum hydride to give (5)-2-ethoxyethyl-1,2-propanediol (311) followed by Swem oxidation to the aldehyde [189]. 

Racemic 1 and 2a were not resolved into their two enantiomers on a Cylodex B chiral stationary phase GC column (J W Scientific), and so the absolute configurations of insect-produced 1 and 2a were determined by derivatization with a chiral derivatizing reagent followed by GC analysis of the resulting diastereomers on an achiral column. Thus, racemic lavandulol, a sanq)le of (R)-(-)-lavandulol, and a hydrolyzed sample of the insect-produced conq)ound were derivatized with acetyl (5)-lactic acid chloride and pyridine in ether to form the acetyl lactate ester(s) (75). The diastereomeric derivatives from racemic lavandulol were resolved almost to baseline, with the derivative from (7 )-lavandulol (isolated from lavender oil) being the later eluting peak. 

Lactic acid is commercially used in food, beverages and industrial applications, as well as in pharmaceuticals and personal care products. It is also the monomeric precursor for polylactic acid (PLA). Market growth in the industrial applications segment is expected to result primarily from lactic acid-based biodegradable polymers for food and nonfood packaging, bottles and fibre applications, and lactate esters [16]. 

As shown in the step 3, the ethanol is used to react with fermented lactic acid via an esterification reaction to form ethyl lactate (generally known as lactate ester). The reason lactate ester is preferable over lactic acid for conversion into lactic acid prepolymer is because lactic acid has a corrosive nature. Therefore, synthesizing PLA from lactic ester can help to reduce costs by avoiding the need to invest in corrosive-resistant reactors and equipment. This represents significant cost reduction in the long term. 

Another very important ch ical that has been made from biological feedstocks by fermentation for many years is lactic acid. Lactic acid is the most important hydrocarboxylic acid and is nsed to make a number of chemicals including pyruvic acid, acrylic acid, 1,2-propauediol, lactate esters, and polylactic add polymer. Fermentation of glucose with the intermediate prodnction of pyruvic acid is the leading process for making lactic acid, as shown in Reaction 16.10 ... 

Although LA production by LAB is very efficient, further improvements in the process can help make it more cost competitive with petroleum-based polymers for PL A production. Environmentally friendly, green solvents are another potential area for lactic acid derivatives, particularly lactate esters of low-molecular-weight alcohols such as ethyl, propyl and butyl lactate (John et al. 2007 Delgado et al. 2010). From that perspective the lactate esters have also further applications in order to run alternative downstream technology (Kamble et al. 2012) and PLA polymerization process (Marques et al. 2012). 

DPPA has been used for the direct C-acylation of methyl isocyanoacetate with carboxylic acids to give 4-methoxycarbonyloxazoles. t-Daunosamine, the glycone component of anticancer anthracycline antibiotics, has been synthesized from L-lactic acid in 9 steps with a 24% overall yield, where a key step in the sequence is the direct C-acylation of methyl isocyanoacetate with the lithium salt of the lactate ester using diphenyl phosphorazidate (eq 7). 

Lactate esters of the 5 -carbon phenylpyrazoles 2 and JV485 were prepared from common intermediate 23 (Figure 5). Conversion of the S -methyl group of phenylpyrazole 23 to carboxylic acid 24 was achieved by Mid-Century oxidation with molecular oxygen in the presence of cobalt and manganese catalysts (77). Halogenation of 24 with chlorine gas or bromine in acetic acid gave 25 which can be esterified to provide either JV 485 or other derivatives such as chiral lactate ester 26. 

Furfuryl acetate. Reflux a mixture of 39 2 g. (34-8 ml.) of redistilled furfuryl alcohol, 48 g. of glacial acetic acid, 150 ml. of benzene and 20 g. of Zeo-Karb 225/H in a 500 ml. bolt-head flask, using the apparatus described under iaoPropyl Lactate. After 3 hours, when the rate of collection of water in the water separator is extremely slow, allow to cool, separate the resin by suction filtration, and wash it with three 15 ml. portions of benzene. Remove the benzene, etc., from the combined filtrate and washings under reduced pressure (water pump) and then collect the crude ester at 74-90°/10 mm. a small sohd residue remains in the flask. Redistil the crude ester from a Claisen flask with fractionating side arm pure furfuryl acetate passes over at 79-80°/17 mm. The yield is 14 -5 g. 

Ammonium lactate [34302-65-3] ia coaceatrated aqueous solutioas has beea coaverted to ammonia and the ester by alcoholysis at temperatures ranging from 100—200°C usiag a variety of alcohols and water entrainers, such as toluene. Ester yields ranging from 50—80% were obtained. This method has also been suggested as a recovery and purification method from impure solutions of lactate (29). However, a considerable amount of the lactate is not converted to the recoverable ester and is lost as lactamide (6). 

Medium Boiling Esters. Esterificatioa of ethyl and propyl alcohols, ethylene glycol, and glycerol with various acids, eg, chloro- or bromoacetic, or pymvic, by the use of a third component such as bensene, toluene, hexane, cyclohexane, or carbon tetrachloride to remove the water produced is quite common. Bensene has been used as a co-solvent ia the preparatioa of methyl pymvate from pymvic acid (101). The preparatioa of ethyl lactate is described as an example of the general procedure (102). A mixture of 1 mol 80% lactic acid and 2.3 mol 95% ethyl alcohol is added to a volume of benzene equal to half that of the alcohol (ca 43 mL), and the resulting mixture is refluxed for several hours. When distilled, the overhead condensate separates iato layers. The lower layer is extracted to recover the benzene and alcohol, and the water is discarded. The upper layer is returned to the column for reflux. After all the water is removed from the reaction mixture, the excess of alcohol and benzene is removed by distillation, and the ester is fractionated to isolate the pure ester. 

The crystal structure of the adduct of titanium tetrachloride and the ester formed from ethyl 2-hydroxypropanoate (ethyl lactate) and acrylic acid has been solved. It is a chelated structure with the oxygen donor atoms being incorporated into the titanium coordination sphere along with the four chloride anions. 

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