Formyl acetate, alkyl

Depending on the respective reaction partner, acetic acid esters can react either as C-H acidic compounds or as acylating agents. Both are illustrated by the self-condensation of ethyl [ 1 acetate in the presence of 0.5 equivalent of sodium ethoxide or triphenymethyl sodium to give ethyl [1,3- C2]acetoacetate (Claisen condensation). In the first case, however, because of the relatively low radiochemical yields (40-45%) obtained by this procedure, it is of minor importance for the preparation of labeled ethyl acetoacetate. The deprotonation of alkyl acetates with LiHMDS followed by acylation with unlabeled or labeled acyl halides to labeled give /3-keto esters is discussed in Section 6.4. Claisen condensation of alkyl [ CJacetates with esters lacking a-hydrogens (i.e. ethyl formate, diethyl oxalate, aromatic/heteroaromatic carboxylic acid esters) proceed unidirectionally and are valuable pathways in the synthesis of ethyl [ C]formyl acetate (521. diethyl [ C]-oxaloacetate (53) and ethyl 3-oxo-3-pyrid-3-yl[2- C]acetate (54). The last example... 

Hydrazinopyridazines are easily formylated with formic acid or ethyl formate and acety-lated with acetic anhydride. A-Pyridazinylthiosemicarbazides are obtained from thiocyanates or alkyl- and aryl-isothiocyanates. Hydrazinopyridazines condense with aliphatic and aromatic aldehydes and ketones to give hydrazones. 

Phenylthio-l-trimethylsilylalkanes are easily prepared by the alkylation of (phenylthioXtrimethylsilyl)mcthane as shown in Scheme 10 [40], The treatment of (phenylthio)(trimethylsilyl)methane with butyllithium/tetramethylethylene-diamine (TMEDA) in hexane followed by the addition of alkyl halides or epoxides produces alkylation products which can be oxidized electrochemically to yield the acetals. Since acetals are readily hydrolyzed to aldehydes, (phenylthioXtrimethylsilyl)methane provides a synthon of the formyl anion. This is an alternative to the oxidative transformation of a-thiosilanes to aldehydes via Sila-Pummerer rearrangement under application of MCPBA as oxidant [40, 41]. 

The authors of this review have developed a straightforward procedure for the synthesis of unsubstituted and alkyl-substituted thieno-thiophenes 1, 2, and 3 the method involves intramolecular condensation of ortho-bifunctional thiophene derivatives. Vilsmeier formylation of an alkyl (5-ethyl-2-thienylthio)acetate (53) furnishes the (5-ethyl-3-formyl-. 2-thienylthio)acetate (54) which when heated with alcoholic sodium... 

The behaviour of the ruthenium catalysts is quite different from that previously reported for cobalt carbonyl catalysts, which give a mixture of aldehydes and their acetals by formylation of the alkyl group of the orthoformate (19). The activity of rhodium catalysts, with and without iodide promoters,is limited to the first step of the hydrogenation to diethoxymethane and to a simple carbonylation or formylation of the ethyl groups to propionates and propionaldehyde derivatives (20). 

Diethylamino)sulfur trifluoride, 110 Formylation (see also Carbonylation) Vilsmeier reagent, 341 Fragmentation reactions Cerium(IV) ammonium nitrate, 67 Copper(II) acetate-Iron(II) sulfate, 85 Lead tetraacetate, 155 Friedel-Crafts alkylation Aluminum chloride, 15... 

Alkyl-substituted oxazoles have been found to react with maleic acid or its anhydride in a diene synthesis to yield substituted pyridine readily converted to pyridoxine (39). In this route, ethyl d, 1-alaninate hydrochloride is treated with formic-acetic anhydride to yield ethyl N-formyl d,1-alaninate (78%). This compound is refluxed in chloroform with phosphorous pentoxide (40), quenched with aqueous potassium hydroxide, and the organic layer distilled to give 4-methyl-5-ethoxyoxazole (I) (60%). The resulting oxazole (I) is condensed readily with a number of appropriate dienophiles to form 2-methyl-3-hydroxy-4,5-disubstituted-pyridines containing substituents (III, a, b, c) which could be converted to pyridoxine as follows ... 

Methoxy-a-tetralone (137), which on formylation at room temperature followed by treatment with n-butanethiol in presence of p-toluenesulfonic acid gave the compound (138), which was converted with lithium dimethylcopper and acetic anhydride to (139). Subjection of (139) to dehydrogenation, hydrolysis and methylation, respectively, yielded (140) which was converted to tetralone (141) by reduction, hydrolysis and methylation of pyralidine enamine. Alkylation of (141) with 2-... 

Reaction of electron-rich olefins such as vinyl ethers have not enabled us to observe spectroscopically a complex with cobalt(III) cobaloximes. Nevertheless, the reaction between a cobal(III)oxime, ethyl-vinyl ether, and ethanol gives complete alkylation of the cobalt (33). When the ethanol is not vigorously anhydrous, some formyl-methylcobaloxime (25) (Scheme 7) is formed also and these observations are consistent (34) with the reactions outlined in Scheme 7. When the water concentration was increased, the amount of formylmethyl-cobaloxime also increased at the expense of the acetal. Thus, we anticipated that the analogous reaction with vitamin Bi2, which is impossible to obtain in an anhydrous condition and is best manipulated in... 

Under appropriate conditions activated thiazoles are alkylated at the 5-position 2-amino 4-methylthiazole is alkylated in the 5-position by heating with /-butyl alcohol in sulfuric acid (24). Under similar conditions 4-methyl-2-phenylthiazole is alkylated by cyclohexanol. 2-Acetylamino-4-methylthiazole reacts with dimethylamine and formaldehyde to afford the corresponding Mannich base (25). 2-Hydroxy-4-methyIthiazole fails to react when submitted to Friedel-Crafts benzoylation conditions whereas it reacts normally in Gatter-mann and in Reimer-Tiemann formylation reactions yielding the 5-formyl derivative (26). 2,4-Dimethylthiazole undergoes perfluoroalkylation when heated at 200 °C for 8 h in a sealed tube with perfluoropropyl iodide and sodium acetate (27). 

Bean and Wilkinson have reported deuteriation rates for several alkyl-pyrroles in buffered aqueous dioxan-acetic acid at 25°C [78JCS(P2)72] under these conditions, neither 2-formyl- nor 2-nitropyrrole underwent exchange. Partial rate factors are given in Table 6.2. These show a number of interesting features. 

Ferrocene reacts with acetyl chloride and aluminum chloride to afford the acylated product (287) (Scheme 84). The Friedel-Crafts acylation of (284) is about 3.3 x 10 times faster than that of benzene. Use of these conditions it is difficult to avoid the formation of a disubstituted product unless only a stoichiometric amount of AlCft is used. Thus, while the acyl substituent present in (287) is somewhat deactivating, the relative rate of acylation of (287) is still rapid (1.9 x 10 faster than benzene). Formation of the diacylated product may be avoided by use of acetic anhydride and BF3-Et20. Electrophilic substitution of (284) under Vilsmeyer formylation, Maimich aminomethylation, or acetoxymercuration conditions gives (288), (289), and (290/291), respectively, in good yields. Racemic amine (289) (also available in two steps from (287)) is readily resolved, providing the classic entry to enantiomerically pure ferrocene derivatives that possess central chirality and/or planar chirality. Friedel Crafts alkylation of (284) proceeds with the formation of a mixture of mono- and polyalkyl-substituted ferrocenes. The reaction of (284) with other... 

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