Amides, acidity alkylation

The formation of the above anions ("enolate type) depend on equilibria between the carbon compounds, the base, and the solvent. To ensure a substantial concentration of the anionic synthons in solution the pA" of both the conjugated acid of the base and of the solvent must be higher than the pAT -value of the carbon compound. Alkali hydroxides in water (p/T, 16), alkoxides in the corresponding alcohols (pAT, 20), sodium amide in liquid ammonia (pATj 35), dimsyl sodium in dimethyl sulfoxide (pAT, = 35), sodium hydride, lithium amides, or lithium alkyls in ether or hydrocarbon solvents (pAT, > 40) are common combinations used in synthesis. Sometimes the bases (e.g. methoxides, amides, lithium alkyls) react as nucleophiles, in other words they do not abstract a proton, but their anion undergoes addition and substitution reactions with the carbon compound. If such is the case, sterically hindered bases are employed. A few examples are given below (H.O. House, 1972 I. Kuwajima, 1976). 

Silver fluoborate, reaction with ethyl bromide in ether, 46, 114 Silver nitrate, complexing with phenyl-acetylene, 46, 40 Silver oxide, 46, 83 Silver thiocyanate, 45, 71 Sodium amide, in alkylation of ethyl phenylacetate w ith (2-bromo-ethyl)benzene, 47, 72 in condensation of 2,4-pentanedione and 1 bromobutane to give 2,4-nonanedione, 47, 92 Sodium 2 ammobenzenesulfinate, from reduction of 2 mtrobenzenesul-finic acid, 47, 5... 

A very significant mortality in Western countries is associated with cardiac arrhythmias Consequently an intensive search is underway for agents to combat this condition - particularly for compounds with an unusual mode of action A class Ic (local anesthetic-like) agent of interest in ihis context is Indecainide (50) One of several routes to this compound covered by patents begins with sodium amide mediated alkylation of 9 cyanofluorene (48) with 3 isopropylamino-1 chloropropane to give amine 49 The synthesis concludes by partial hydrolysis of the nitnle func tion to a carboxamide linkage with sulfunc acid to produce indecainide (50) [15]... 

Doxapram Doxapram, l-ethyl-4-(2-morpholinoethyl)-3,3-diphenyl-2-pyrrolidinone (8.2.4), is synthesized in the following manner. Diphenylacetonitrile in the presence of sodium amide is alkylated with l-ethyl-3-chlorpyrrolidine, giving (l-ethyl-3-pyrrolidinyl) diphenylacetonitrile (8.2.1). Acidic hydrolysis of the nitrile group gives (l-ethyl-3 pyrrolidinyl)diphenylacetic acid (8.2.2). Reacting this with phosphorous tribromide... 

Beside amidation, N-alkylation serves to couple aminolactam 81b to a side chain, as by Sn2 displacement of 2-hydroxy-4-phenylbutyric ester triflate, to yield amino acid ester 82a (87M11). 

Amidation of alkyl aryl ethers.2 Either anisole or phenetole undergoes para-amidation exclusively on reaction with acetohydroxamic acid in polyphosphoric acid (yields 50-60%). Thus phenetole is converted into the drug phenacetin in -50% yield (equation I). 

A less common approach to 2,5-diketopiperazine was reported by Marcaccini et al. [79] who used a Ugi-4CR between amines, aldehydes, isocyanides, and chloroacetic acid to get adducts 140. Treatment of 140 with ethanolic potassium hydroxide led to an intramolecular amide N-alkylation reaction, giving 2,5-diketopiperazines 141... 

An amide name is based on the name of the carboxylic acid of the same number of carbon atoms, but the -oic ending is changed to amide. Amides with alkyl groups on the nitrogen are substituted amides and are named the same as N-substituted amides, except the parent name is preceded by the name of the alkyl substituent and a capital N precedes the substituent name. 

Acidic reaction conditions can also lead to protonation of some leaving groups, thereby increasing their reactivity in nucleophilic substitutions. Such groups include, for instance, alcohols, ethers, amines, amides, or alkyl fluorides. 

Selective fluorination of a wide variety of carbanions has been carried out very effectively with iV-fluoro-Y-alkyl sulfonamides by Barnette63. Treatment of carbanions of malonates, enolates of ketones, acids and amides, and alkyl and aryl organometallics results in the transfer of fluorine from nitrogen to carbon (equation 43). Yields are fair to... 

Aldol Reactions. Pseudoephedrine amide enolates have been shown to undergo highly diastereoselective aldol addition reactions, providing enantiomerically enriched p-hydroxy acids, esters, ketones, and their derivatives (Table 11). The optimized procedure for the reaction requires enolization of the pseudoephedrine amide substrate with LDA followed by transmeta-lation with 2 equiv of ZrCp2Cl2 at —78°C and addition of the aldehyde electrophile at — 105°C. It is noteworthy that the reaction did not require the addition of lithium chloride to favor product formation as is necessary in many other pseudoephedrine amide enolate alkylation reactions. The stereochemistry of the alkylation is the same as that observed with alkyl halides and the formation of the 2, i-syn aldol adduct is favored. The tendency of zirconium enolates to form syn aldol products has been previously reported. The p-hydroxy amide products obtained can be readily transformed into the corresponding acids, esters, and ketones as reported with other alkylated pseudoephedrine amides. An asymmetric aldol reaction between an (S,S)-(+)-pseudoephe-drine-based arylacetamide and paraformaldehyde has been used to prepare enantiomerically pure isoflavanones. ... 

Under these conditions esters, carboxylic acids, lactones, amides, nitriles, alkyl halides, and nilro compounds arc not reduced. Some of the groups are reduced, however, in refluxing 2-cthyHiexanol (I30 ). 

Substituting the amide or alkyl amides of chloracetic add for the acid itself, the following type of compound is produced ... 

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