Esters ethoxy formates

Formation of quinuclidine-3-carboxylic acid derivatives (68) from these reactions was conclusive proof of saponification of the ethoxy-carbonyl group at position 2 of the diester (61). A similar reaction takes place with diethyl quinuclidine-2,3-dicarboxylate.100 This is in agreement with the known principle of easier saponification of a- than j8-amino acid esters. Some 3-(j8-acyloxyethyl)-2-diethylaminomethyl-quinuclidines (69, 70)123 on distillation at atmospheric pressure cyclize with loss of ester and formation of a new tricyclic system, quinuclidino[2,3-c]piperidine (72). The same reaction takes place by heating the corresponding amino alcohol (71) with phthalic anhydride in the presence of benzenesulfonic acid.123... 

Note also that if another ester, of general formula R-COOCjHj, were used in place of benzaldehyde in the above reaction, a similar complex would be formed, and on acidification would give an unstable p-hydroxy-P-ethoxy ester, which would very readily lose ethanol with the formation of a 3-keto-ester. 

The reason for this relative lack of reactivity of 2-methylthiazoIium is probably due to the too-weak nucleophilic character of its carbon-2. For example, any /S-alkoxyalcene (29) derivatives resulting from the condensation of o-ester could never have been isolated, whereas they constitute the essential intermediate step in trimethine syntheses for rings of acidic character (64). However, even if a negative 5-substituent such as ethoxy-carbonyl increases the yield (61) by promoting independently the possible formation of the methylene base, it may be stressed that the presence of this base is not the essential condition of the reaction, since the isolated anhydrobase itself is not reactive toward the o-ester (Scheme 41). 

The reaction of oxazoles with alkynes is entirely different, leading to furans. The adducts (157) eliminate a cyanide in a retro-Diels-Alder process (equation 15). A typical example is the formation of the ester (164) from 5-ethoxy-4-methyloxazole and dimethyl acety-lenedicarboxylate (equation 16) equation (17) illustrates the production of two regioisomers in this reaction (79MI41802) a more elaborate case is the twofold addition of benzyne to 4-methyl-2,5-diphenyloxazole to give the bridged dihydroanthracene shown in equation (18) (80TL3627). 

An overall comparison of the results of tests using brine indicates that ethoxylated alcohols and ethoxylated alcohol sulfates were superior for mobility control in enhanced oil recovery. It was found that the optimum hydrophobe for ethoxylated alcohol is a mixture with an average chain length of about 13 carbon atoms. The degree of ethoxylation is also important. It was found that 6 ethoxy late groups is close to the optimum. The formation of the sulfate ester tended to lessen the effect of chain length and reduce the optimum number of ethoxylate groups to 5. 

Ethyl Chlor Formate.—The compound formed is an ethyl ester of chlor formic acid, and indicates that carbonyl chloride is the acid chloride of chlor formic acid. By further action of sodium alcoholate, however, the second chlorine atom is replaced by the ethoxy group. 

Displacement of an ethoxy attached to a vinylic side-chain occurs in mineral acid at ambient temperature with concurrent formation of a C—C bond [2042]. Ethereal hydrogen chloride annulates nitro and side-chain epoxide groups intramolecular reduction-oxidation leads to the 4-quinolinone in high yields [2314]. A C—N bond is formed when a methylthiovinylpyrrole is treated with a strong base and a malonic ester. Lactim ethers such as 5-methoxy-2 -pyrrole condense with acetonedicarboxylate in a base-induced cyclization at room temperature [3258]. 

Additional evidence for a concerted reaction of two metalloformyl radical units Rh—CO comes from studies of reactions with ethanol, resulting in predominant formation of the formyl-ethoxy ester. Reaction of ethanol with Rh—CO units from two separate molecules would yield the nonobserved symmetrical products [(H(0)C)Rh (por)-tether-(por)Rh (C(0)H)] and [(OEt(0)C)Rh (por)-tether-(por)Rh -(C(0)OEt)]. In addition, nonconcerted reaction of ethanol with a monocarbonyl complex [Rh (por)-tether-(por)Rh (CO)] would yield nonobserved species containing Rh—H units. Taken together, it seems most likely that the formation of Rh C(0)H and Rh —C(0)Y units proceeds a concerted cleavage of the H Y bonds via a trimolecular transition state, as shown in Fig. 44. 

Attempts have also been made338 346 to find a theoretical explanation of the stereo or positional selectivity in the first stage of the heterodiene synthesis, especially in the interaction between 5-ethoxy-4-methyloxazole and asymmetric dienophiles, e.g., /9-acetylacrylic acid and its ethyl ester. ir-Electron density calculations for the diene and dienophile molecules by the HMO method indicate the formation of the 4-acetylpyridine derivative (187) from ethyl /3-acetylacrylate, while the opposite orientation would be expected in the reaction with the free acid, giving a substituted 5-acetylpyridine as the main product. Indeed, 5-ethoxy-4-methyloxazole on condensation with ethyl /3-acetylacrylate affords only 187, while in the condensation with /3-acetylacrylic acid, only 2-methyl-3-hydroxy-5-acetylpyridine (188) is isolated.338 348... 

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