Diesters, reaction with

Esters. Neopentyl glycol diesters are usually Hquids or low melting soflds. Polyesters of neopentyl glycol, and in particular unsaturated polyesters, are prepared by reaction with polybasic acids at atmospheric pressure. High molecular weight linear polyesters (qv) are prepared by the reaction of neopentyl glycol and the ester (usually the methyl ester) of a dibasic acid through transesterification (37—38). The reaction is usually performed at elevated temperatures, in vacuo, in the presence of a metallic catalyst. 

Natural Products. Many natural products, eg, sugars, starches, and cellulose, contain hydroxyl groups that react with propylene oxide. Base-cataly2ed reactions yield propylene glycol monoethers and poly(propylene glycol) ethers (61—64). Reaction with fatty acids results ia a mixture of mono- and diesters (65). Cellulose fibers, eg, cotton (qv), have been treated with propylene oxide (66—68). 

Fig. 2. Synthesis of uma2enil (18). The isonitrosoacetanihde is synthesized from 4-f1iioroani1ine. Cyclization using sulfuric acid is followed by oxidization using peracetic acid to the isatoic anhydride. Reaction of sarcosine in DMF and acetic acid leads to the benzodiazepine-2,5-dione. Deprotonation, phosphorylation, and subsequent reaction with diethyl malonate leads to the diester. After selective hydrolysis and decarboxylation the resulting monoester is nitrosated and catalyticaHy hydrogenated to the aminoester. Introduction of the final carbon atom is accompHshed by reaction of triethyl orthoformate to...

The disadvantage of this method is that the dichloridites and monochloridites are sensitive to water and thus could not be used readily in automated oligonucleotide synthesis. This problem was overcome by Beaucage and Caruthers, who developed the phosphoramidite approach. In this method, derivatives of the form R 0P(NR2)2 react with one equivalent of an alcohol (catalyzed by species such as l//-tetrazole) to form diesters, R OP(OR")NR2, which usually are stable, easily handled solids. These phosphoroamidites are easily converted to phosphite triesters by reaction with a second alcohol (catalyzed by l//-tetrazole). Here, again, oxidation of the phosphite triester with aqueous iodine affords the phosphate triester. Over the years, numerous protective groups and amines have been examined for use in this approach. Much of the work has been reviewed. ... 

The intramolecular condensation reaction of diesters, the Dieckmann condensation, works best for the formation of 5- to 7-membered rings larger rings are formed with low yields, and the acyloin condensation may then be a faster competitive reaction. With non-symmetric diesters two different products can be formed. The desired product may be obtained regioselectively by a modified procedure using a solid support—e.g with a polystyrene 10 ... 

A functional group is introduced to the polystyrene 10 by chloromethylation Blanc reaction) in order to allow for reaction with the substrate 11. The polymer-bound diester is then treated with base to initiate the Dieckmann condensation. 

The ring-contracted analog of alphaprodine is prepared by a variation of the scheme above. Alkylation of 109 with ethyl bromoacetate affords the lower homolog diester (115). Dieckmann cyclization followed by saponification-decarboxylation yields the pyrrolidine (116). Reaction with phenylmagnesium bromide leads to the condensation product (117) acylation with propionic anhydride gives the analgesic agent prolidine (118)... 

For example. 2-ethoxyindole (1 a) with the alkyne diester in refluxing dioxane yields dimethyl 2-ethoxy-3//-l-benzazepine-3,4-dicarboxylate (2) as a minor product along with a 50 % yield of a mixture of the cis- and tran.v-indol-3-ylacrylates 3.20 However, with 2-ethoxy-l-methylindole (1 b) the l//-l-benzazepine 4 becomes the major product. An analogous reaction with l,2-bis(trifluoromethyl)acetylene to yield 2-ethoxy-l -methyl-3,4-bis(trifluoroiriethyl)-1 //-1-benzazepine has been performed however, the yield was not reported.142... 

Reaction of Unsaturated Compounds with Dialkyl Phosphites The diesters of phosphorous acid are somewhat resistant to oxidation and used as intermediates for the reaction with olefins forming phosphonic acids. The reaction takes place in the presence of free radical initiators, such as di-/-bu-tyl peroxide [104,105]. 

Phosphonous acid diesters undergo the Arbusov reaction with a wide variety of organic halides, giving esters of secondary phosphinic acids, as is demonstrated in Eq. (88) ... 

In this section primarily reductions of aldehydes, ketones, and esters with sodium, lithium, and potassium in the presence of TCS 14 are discussed closely related reductions with metals such as Zn, Mg, Mn, Sm, Ti, etc., in the presence of TCS 14 are described in Section 13.2. Treatment of ethyl isobutyrate with sodium in the presence of TCS 14 in toluene affords the O-silylated Riihlmann-acyloin-condensation product 1915, which can be readily desilylated to the free acyloin 1916 [119]. Further reactions of methyl or ethyl 1,2- or 1,4-dicarboxylates are discussed elsewhere [120-122]. The same reaction with trimethylsilyl isobutyrate affords the C,0-silylated alcohol 1917, in 72% yield, which is desilylated to 1918 [123] (Scheme 12.34). Likewise, reduction of the diesters 1919 affords the cyclized O-silylated acyloin products 1920 in high yields, which give on saponification the acyloins 1921 [119]. Whereas electroreduction on a Mg-electrode in the presence of MesSiCl 14 converts esters such as ethyl cyclohexane-carboxylate via 1922 and subsequent saponification into acyloins such as 1923 [124], electroreduction of esters such as ethyl cyclohexylcarboxylate using a Mg-electrode without Me3SiCl 14 yields 1,2-ketones such as 1924 [125] (Scheme 12.34). 

Figure 17-22. Polyadduct from triethyl phosphate and phosphorous pentox-ide and reaction with hexanol to produce a diester.

This is an equilibrium process and two techniques are used to drive the reaction to completion. One is to use a large excess of the alcohol, which is feasible for simple and inexpensive alcohols. The second method is to drive the reaction forward by irreversible removal of water, and azeotropic distillation is one way to accomplish this. Entries 1 to 4 in Scheme 3.5 are examples of acid-catalyzed esterifications. Entry 5 is the preparation of a diester starting with an anhydride. The initial opening of the anhydride ring is followed by an acid-catalyzed esterification. 

Alcohols can be phosphorylated to phosphoric diesters by ionic phosphoric monoimidazolides in acetone at temperatures of about 50-60 °C over the course of several hours. These imidazolides are generally prepared by reaction of the appropriate phosphate with CDI (see Section 2.2). Reactions with ethyl, -butyl, w-pentyl, -octyl benzyl alcohol and various other alcohols have also been described.[1]... 

The photochemical fragmentation of vinyl-substituted 1,2k5-oxaphosphetanes, representing a step of a photochemical variant of the Wittig reaction with methyl-eneoxophosphoranes, has been examined as a model in the case of 22b20). Photolysis of this compound in methanol affords the 1,3-diene 24b as well as the highly reactive dioxophosphorane 23 which is trapped by the solvent subsequent esterification of the half-ester 62, formed as a primary product, with diazomethane to give the diester 63 was undertaken solely for preparative reasons 20). 

Reaction with epoxides gives the dangerously unstable and explosive mixed nitrate-perchlorate diesters, such as 1,2-ethanediyl nitrate perchlorate from ethylene oxide. 

The reaction of cycloheptaamylose with diaryl carbonates and with diaryl methylphosphonates provides a system in which a carboxylic acid derivative can be directly compared with a structurally analogous organo-phosphorus compound (Brass and Bender, 1972). The alkaline hydrolysis of these materials proceeds in twro steps, each of which is associated with the appearance of one mole of phenol (Scheme Y). The relative rates of the two steps, however, are reversed. Whereas the alkaline hydrolysis of carbonate diesters proceeds with the release of two moles of phenol in a first-order process (kh > fca), the hydrolysis of methylphosphonate diesters proceeds with the release of only one mole of phenol to produce a relatively stable aryl methylphosphonate intermediate (fca > kb), In contrast, kinetically identical pathways are observed for the reaction of cycloheptaamylose with these different substrates—in both cases, two moles of phenol are released in a first-order process.3 Maximal catalytic rate constants for the appearance of phenol are presented in Table XI. Unlike the reaction of cycloheptaamylose with m- and with p-nitrophenyl methylphosphonate discussed earlier, the reaction of cycloheptaamylose with diaryl methylphosphonates... 

In contrast to ethyl diazoacetate, diethyl diazomalonate reacts with allyl bromide in the presence of Rh2(OAc)4 to give the ylide-derived diester favored by far over the cyclopropane (at 60 °C 93 7 ratio). This finding bespeaks the greater electrophilic selectivity of the carbenoid derived from ethyl diazomalonate. For reasons unknown, this property is not expressed, however, in the reaction with allyl chloride, as the carbenoids from both ethyl diazoacetate and diethyl diazomalonate exhibit a similarly high preference for cyclopropanation. 

Lack of selectivity in the reaction of the /3-D-glucoside derivative with one molar equivalent of benzylthiocarbonyl chloride has also been noted 40% of the 2,3-diester and 40% of the starting material were isolated.40 Similarly, unimolar benzoylation of phenyl 4,6-0-benzylidene-/3-D-glucopyranoside gave only 9% of the 3-ester, together with 47% of the 2,3-diester.41 Acylation of benzyl 4,6-0-benzylidene-/8-D-glucopyranoside with acetic anhydride-pyridine-pyridine hydrochloride yielded,42 in contrast to the reaction with the... 

Differentiation between the secondary hydroxyl groups in methyl 4,6-O-benzylidene-a-D-glucopyranoside was observed on reaction with methyl benzoate-sodium methoxide at 200° for 45 minutes the 2- and 3-esters and the 2,3-diester were formed176 in the molar ratios of 55 23 10. 

Succinylosuccinic diester is cyclized according to the common route by using chlorinated or methylated aniline. Starting from anilines which are substituted in 2- or 4-position, the reaction affords the symmetrical 4,11- or 2,9-disubstitution products. Reaction with 3-substituted anilines, on the other hand, produces a mixture of both of the symmetrical 1,8- and 3,10-disubstitution products, as well as un-symmetrical 1,10-disubstituted compound. The following chart illustrates this point. 

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