Acetic cyano-,esters

The formation of ethyl cyano(pentafluorophenyl)acetate illustrates the intermolecular nucleophilic displacement of fluoride ion from an aromatic ring by a stabilized carbanion. The reaction proceeds readily as a result of the activation imparted by the electron-withdrawing fluorine atoms. The selective hydrolysis of a cyano ester to a nitrile has been described. (Pentafluorophenyl)acetonitrile has also been prepared by cyanide displacement on (pentafluorophenyl)methyl halides. However, this direct displacement is always aecompanied by an undesirable side reaetion to yield 15-20% of 2,3-bis(pentafluoro-phenyl)propionitrile. 

This cyano-ester is hydrolysed by boiling with concentrated hydrochloric acid with the formationof pentane-ay -tricarboxylic acid, CO H. CH (CHj. CHj. COjH) andiwhen the sodium salt of this acid is heat with acetic anhydride and distilled, decomposition takes place with the formation of 8-ketohexahydrobenzoic acid or cyclohexanone-4-carboxylic acid—... 

Hydrolysis of this cyano-ester gives pentane-ays-tricarboxylic acid, which on digestion with acetic anhydride and subsequent distillation yields S-keto-h e xahy dr o -b en zoic acid ... 

A convenient procedure has been developed for the synthesis of cyano ester is prepared and treated with hydrogen cyanide in a single operation. For this purpose, a hot mixture of the carbonyl compound, cyanoacetic ester, and pyridyl acetate s treated with ethanol and potassium cyanide. 

Alkylations of boron-stabilized carbanions have been carried out with primary alkyl halides containing acetal, alkene, alkyne, chloride, cyano, ester and tosylate groups, though a ketone group was not tolerated. ... 

Steroidal ketones have been used extensively in the Knoevenagel reaction. Thus, die transformation of 17-oxoandrostane derivatives (309), which are readily available by microbiological degradation of sitosterin, are employed for the synthesis of enantiomerically pure cardiotonic steroids such as bufa-dienolide and cardenolide (311). In toth syntheses the substitutent at C-17 is introduced by a Knoevenagel reaction of the 17-oxoandrostane derivative (309) with ethyl cyanoacetate in the presence of ammonium acetate to give the cyano ester (310), presumably as a mixture of the ( )- and (Z)-isomers, in 89% yield.5 5... 

C2-homologizati on of sugars with, 264-265 Acetamide, JV-bromo- (AcNHBr, NBA) bromohydrination with, 275-276, 287 Acetaminophen (= paracetamol), 301 Acetate, piperidinium cat. for aldol add., 82 —, sodium a-epimerization of ketones, 277 opening of oxiranes, 282 Acetic acid, anhydride (AcfO) protection with. See Protection Pummerer rearr. with, 51, 265 —, esters (See also Protection of hydroxy groups) C-H acidity, 10 1-methylethenyi ester pr., 174 transenolization, 58 —, bromo-, esters pr., 179 a2-synthon, 19, 65, 309 d2-synthon, 19, 301 —, chloro-, esters pr., 179 hydantoins from, 308 —, cyano-, esters pr., 177 pyrrolines from, 298 —, (dialkoxyphosphinyl)-, esters pr 188 Wittig-Horner olefinations, 267, 282 —, diazo-, ethyl ester pr, 176, 178 cyclopropanes from, 74—75 —, dichloro- deblocking of pixyl ethers, 342 —, hydroxy-, esters pr., 176 —, hydroxyphenyl-, (S)- (l-mandelic acid) ... 

Recent methods for the cleavage of allyl ethers that have that have yet to be tested on the anvil of complex target synthesis include (a) diborane generated in sUu by reaction of sodium borohydride with iodine in THF at 0 (cyano, ester, nitro, acetonide and tetrahydropyranyl groups survive) (b) cerium(ni) chloride and sodium iodide in refluxing acetonitrile (benzyl. THP and Boc groups survive) (c) iodotrimethylsilane in acetonitrile at room temperature/ and (d) DDO in wet dichloromethane (secondary allyl ethers, benzyl, acetate and TBS groups survive). ... 

Cyclobutanone alkyl silyl acetals, obtained from [2-f2] cycloadditions, can be deprotected with 1 equiv of TBAF in THF to give the open-chain cyano esters in excellent yields (eq 5). When 4-chloro-2-cyanocyclobutane alkyl silyl acetals are used as substrates for this reaction, ( 7Z) mixtures of 2-cyanocycloprop-anecarboxylates are obtained by an intramolecular cyclization (eq 6). 

This reaction has been extended to the condensation between amidine and )0-cyano ester, amidine and )(3-hydroxyacetylene, amidine and malonate, A -vinyl amidine and acetal, and a three-component reaction of amidine with aldehyde and acetylene A ... 

Cyano-esters can also be condensed with other nitriles, as in the reaction of methyl a-cyano acetate and a-amino acetonitrile to give 4.6. Initial condensation of the cyano-ester enolate with the "other" nitrile moiety gave an iminium salt. Subsequent reaction with aqueous acid led to an imine, which isometizes to the... 

Aminomethylation Reaction. The Hf(OTf)4-dopedMe3SiCl system was used as Lewis acid to catalyze the aminomethylation of electron-rich aromatic compounds. Suitable arenes include indoles, furans, pyrroles, thiophenes, and anilines, with new t)q)es of iV,0-acetals having a variety of functional groups, such as cyano, ester, bis(trimethylsilyl)amino, diallylamino, and cyclic amino moieties. This method allowed for the facile synthesis of nonnatural aromatic amino acid derivatives (eq 1). 4 Aminomethylation using a A, 0-acetal with a bis(trimethylsilyl)amino group was particularly successful in the direct preparation of a N-unsubstituted a-indolylglycine derivative, which required only a standard aqueous workup as the deprotective step. ... 

Unlike the chiral, neutral N-F reagents, the [N-F] ammonium salts of cinchona alkaloids are employed for the fluorination of a number of substrates ketone and ester enolates, (3-keto esters, a-cyano esters, a-nitro esters, a-amino esters, silyl enol ethers, enol acetates, nitrile anions, and... 

Pyrethroid Esters of Benzene Acetate. These insecticides have more extensive stmctural optimization in both acid and alcohol moieties. Fenvalerate [51630-58-17, a-cyano-(3-phenoxyphenyl)methyl (+)-(2R,5)"Ct"isoprop5i-4-chlorophenylacetate (24) d 1.17, vp 1.4 p.Pa at 25°C), a mixture of four isomers, is soluble in water to 0.3 mg/L The rat oral LD q is 450 mg/kg. Esfenvalerate [66230-04-4] is the (+)-2-(i, 5)-isomer (mp 59°C). The rat LD qS are 75, 458 (oral), and the rabbit dermal LD q is 2000 mg/kg. These pyrethroids are widely used general-purpose insecticides for field, vegetable, and fmit crops. 

---