Carboxylic acid esters with

M. Krull, S. P. von Halasz, W. Reimann, J. Balzer, and H. Geiss. Copolymers of ethylenically unsaturated carboxylic acid esters with polyoxyalkylene ethers of lower, unsaturated alcohols as flow-improving agents for paraffin containing oils. Patent US 5718821, 1998. 

Trihydroxybenzene carboxylic acid esters with a sugar are characteristic of hydrolyzable tannins .37 These, too, may be present in coffee... 

The first synthetically useful reaction of titanium complexes of type 4, leading to the formation of two new carbon—carbon bonds, was developed by Kulinkovich et al. [55]. They found that treatment of a carboxylic acid ester with a mixture of one equivalent of titanium tetraisopropoxide and an excess of ethylmagnesium bromide at —78 to —40 °C affords 1-alkylcyclopropanols 9 in good to excellent yields (Scheme 11.2) [55,56], This efficient transformation can also be carried out with sub-stoichiometric amounts of Ti(OiPr)4 (5—10 mol%) [57,58]. In this case, an ethereal solution of two equivalents of EtMgBr is added at room temperature to a solution containing the ester and Ti(OiPr)4. Selected examples of this transformation are presented in Table 11.1 (for more examples, see ref. [26a]). 

First of all a 2-substituted oxazoline (1) is formed by cyclocondensation of a carboxylic acid ester with 2-aminoethanol and a small amount of (1) is converted with an alkylating agent (e.g., methyl tosylate) to the activated, ionic form (2). 

The principal method for preparation of pyrazino[2,3- [l,3]oxazines, as reported in CHEC-II(1996) <1996CHEC-II(7)737> involves cyclization of a 2-aminopyrazine-3-carboxylic acid ester with an aromatic acid chloride. Further applications of this three-step approach have been reported <19948405, 2000BMC2803>, but a one-pot approach has also been developed (Equation 157). This cyclization has also been carried out using acetic anhydride in place of an acid chloride <2005JMT(741)67>. 

From Carboxylic Acid Esters with 1-Lithiocyclopropyl Sulfoxides and from Cyclopropanecarbaldehydes with 2-Lithio-l,3-oxathianes... 

Michael additions of nitromethane. Italian chemists were able to effect Michael addition of nitromethane to z,/ -unsaturated carboxylic acid esters with catalysis by lelramethylguanidine. Yields of 1 1 adducts (1) are in the range 50-85 % when R or R are alkyl or aryl groups. If R and R are H, I 2 adducts (2) are also formed in substantial amounts. 

Kuhlmann has reviewed the reactions of carboxylic acid esters with sodium in the presenee of trimethylchlorosilane. 

Ethyl 3-ethoxy-a-nitroacrylate with 1,1-diphenylhydrazine in ethanol followed by heating has been shown to give l,4-bis(diphenylamino)-2,5-diethoxycarbonyl-l,4-dihydropyrazine (1586). A small amount of 2,5-dicyano-l,4-bis(dimethylamino)-1,4-dihydropyrazine was obtained from the reaction of 2-chloro-3-(2, 2-dimethyl-hydrazino)propionitrile [(Me)2NNHCH2CH(Cl)CN] with sodium hydride (1587). Hexaalkyl-l,4-dihydropyrazines and other 1,4-dialkyl-1,4-dihydropyrazines can be obtained by thermolysis of the products of reaction of a-(alkylamino)carboxylic acid esters with alkylmagnesium bromide. Thus the reaction of ethyl a-s-butyl-aminopropionate with ethylmapesium bromide, followed by heating in vacuo to 250-300°, gave 2,5-dimethyl-3,6-diethyl-l,4-di-s-butyl-l,4-dihydropyrazine (1588). 

In order to obtain cyclization of an N-a-carboxy dithiocarbamic acid (CLXXXI) to the thiazolidin-5-one-2-thione (CLXIII), dehydrating agents are necessary. These same products may, however, be obtained by simply warming the a-amino carboxylic acid esters with carbon disulfide, especially when there is an aromatic ring attached to the -carbon atom (method D). In this way a-(methylamino) phenylacetic acid and carbon disulfide yield 3-methyl-4-phenylthiazolidin-5-one-2-thione [121) (Table 24). 

As well as the above-described intermolecular alcoholysis of esters, the intramolecular version has been successfully utilized for the synthesis of lactones from racemic hydroxy carboxylic acid esters (25-41, 64—66) (Table 11.1-22). High selectivity in the pig pancreas lipase-catalyzed enantiomer-differentiating lactonization of y-hydroxy carboxylic acid esters with formation of butyrolactones substituted in... 

Propantel Prop-antelina bromuro Propantheline bromide PiDpanthelini bromidum SC-3171 Xanthene- carboxylic acid, ester with (2-hydroxyethyi)diisoprapylmethylammonium brom-ide. Anticholinergic agent, mp - 159-161 very soluble in H2O, EtOH, CHQ3, insoluble in Et20, CeHe. Ellis Everard. 

Pro-azaphosphatrane lb catalyzes the transesterification of carboxylic acid esters with high selectivity and in excellent yields at 25 °C. The success with simple esters prompted us to turn our attention to amino acid esters, since esters are very useful protecting groups in peptide synthesis. When Boc-Val-Phe-OMe was the substrate and allyl alcohol was chosen as the solvent, the use of lb gave a 55 45 mixture of epimers at the phenylalanine residue. By using the more bulky Id as a catalyst, however, the product was isolated in 96% yield with very high diastereomeric purity (98 2). In all cases,yields and selectivities are comparable to those realized with DBU/LiBr in the presence of similar substrates. Catalysts lb and Id are more efficient, however, because only 10-15 mol % is needed whereas the DBU/LiBr system utilizes 50 mol % of DBU and 500 mol % of LiBr [139]. Moreover, our reactions are carried out at room temperature, while other catalysts frequently require refluxing solvent temperatures. 

A new way to prepare peroxy acids was discovered by Novo Nordisk, DK (9-11). They showed that some lipases catalyze the conversion of fatty acids with hydrogen peroxide (preferably 60%) to peroxy fatty acids Novozym 435, an immobilized lipase from Candida antarctica on polyacrylic Lewatit, is the most active and stable biocatalyst for this purpose (Scheme 1). Recently we found that Novozym 435 is also capable of catalyzing perhydrolysis (12), i.e., the reaction of carboxylic acid esters with hydrogen peroxide to percarboxylic acids (Scheme 2). 

Chem. Descrip. Hydroxyfunctional carboxylic acid ester with pigment affinic groups... 

A soln. of startg. ester in dichloromethane treated with 2 eqs. SnC at —70° for 15 min, and the mixture allowed to warm slowly to room temp, over 2 h - product. Y 58%. Reaction is thought to proceed via a cationic oxa-Cope rearrangement. F.e, inch oxepin analogs, also satd. O-heterocyclics from ethylenic derivs., and 3-vinyl-tetrahydrofuran-2-carboxylic acid esters with an allylsilane group as internal nucleophile, s. L.D.M. Lolkema et al.. Tetrahedron Letters 29, 6365-8 (1988). 

Acylamino- from amino-carboxylic acid esters with long-chain fatty acid chlorides s. 16, 492... 

When the base is hydroxide and the reaction is done in water, as in the preparation of 189, this reaction is known as the Schotten-Baumann reaction, after Carl Schotten (Germany 1853-1910) and Eugen Baumann (Germany 1846-1896). Just as amides are prepared from the reaction of carboxylic acid esters with amines or ammonia, so sulfonamides are prepared from sulfonate esters. An example is the reaction of ethyl butanesulfonate (190) with ammonia to give butanesulfonamide, 191. 

Michael additions. In this sense, the preferred formation of the (S)-diastereomers of the Michael adducts 17 generated from the enolate 15 of the diacetone-glucose dithiane-2-carboxylic acid ester with arylidene malonic acid esters 16 can be explained by assuming that the electrophile attacks from the lithium site in a way, which minimizes the steric repulsion between the dithiane ring and the aryl group ( formula A) ... 

Carboxylic acid hydrazides from carboxylic acid esters with ci5-fran5-rearrrangement... 

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