Grignard reagents acetic anhydride

Other Rea.ctlons, The anhydride of neopentanoic acid, neopentanoyl anhydride [1538-75-6] can be made by the reaction of neopentanoic acid with acetic anhydride (25). The reaction of neopentanoic acid with acetone using various catalysts, such as titanium dioxide (26) or 2irconium oxide (27), gives 3,3-dimethyl-2-butanone [75-97-8] commonly referred to as pinacolone. Other routes to pinacolone include the reaction of pivaloyl chloride [3282-30-2] with Grignard reagents (28) and the condensation of neopentanoic acid with acetic acid using a rare-earth oxide catalyst (29). Amides of neopentanoic acid can be prepared direcdy from the acid, from the acid chloride, or from esters, using primary or secondary amines. 

Use of the imonium group for protection of enones was explored. Stability to peracids, lead tetraacetate, bromine, and acetic anhydride was claimed (727). The usual resistance of enamines (but not their salts) to additions of Grignard reagents was used for selective addition to a 3,17-diketosteroid by formation of the usual 3-monoenamine 728). 

By reaction of 3-thienyllithium with magnesium bromide, the Grignard reagent, free from entrainment Grignard reagent, was obtained,- which is useful for the preparation of 3-acetothiophene by reaction with acetic anhydride at —70 0 and for the preparation of 3-t-butoxythiophene through reaction with t-butyl perbenzoate. It is the opinion of the present author that most 3-substituted thiophenes are prepared more conveniently from 3-thienyllithium than from 3-thenyl bromide. The latter method, however, is superior if the introduction of the 3-thenyl group is desired. 

Ullmann condensation of the sodium salt of p-chlorothiophe-nol (31) with 2-iodobenzoic (32) acid gives 33. Cyclization by means of sulfuric acid affords the thioxanthone, 34. Reaction with the Grignard reagent from 3-dimethylaminopropyl chloride affords the tertiary carbinol (35). Dehydration by means of acetic anhydride affords chlorprothixene as a mixture of geometric isomers, 36. (Subsequent work showed the Z isomer-chlorine and amine on the same side—to be the more potent compound.) Chlorprothixene is said to cause less sedation than the phenothiazines. ... 

The N-oxide 267 reacts with acetic anhydride to yield allopurinol 248. Grignard reagents reacted with 267 to yield 268 (76CPB3120). 

Aromatization of a tetrahydroquinolizone (5) by means of acetic anhydride and sulfuric acid or acetic anhydride alone leads to the formation of a variety of mono- or di-substituted quinolizinium compounds. Glover and Jones 8 achieved the synthesis of a number of these derivatives starting from 2-cyanopyridine and condensing it with appropriate Grignard reagents followed by cyclization and aromatization as outlined in Eq. (2). An identical method was simultaneously worked out by Nesmeyanov and Rybinskaya9 for the specific synthesis of 2-substituted quinolizinium compounds. This... 

Benzofuran-3(2/f)-ones (396) exist in the keto form but undergo ready enolization. Acetylation with acetic anhydride and sodium acetate affords 3-acetoxybenzo[6]furans, but reaction under acidic conditions usually supplies these products admixed with 3-acetoxy-2-acetylbenzo[6]furans. Alkylation usually furnishes a mixture of O- and C-alkylated products. 3-Acetoxy-6-methoxy-4-methylbenzo[6]furan, on Vilsmeier reaction, supplies the 3-chlorobenzo[6]furan-2-carbaldehyde, the product expected from an enolizable ketone (72AJC545). Benzofuran-3(2//)-ones react normally with carbonyl reagents. Grignard reagents react in the expected way and dehydration of the intermediate affords a 3-substituted benzo[6]furan. The methylene group is reactive so that self condensation, condensation with aldehydes and ketones and reaction with Michael acceptors all occur readily. 

Trichlorotrifluoroethane and zinc in diethyl ether or dimethylfor-mamide (DMF) form an organometallic complex with diethyl ether [773] or dimethylformamide [114. This complex reacts with aldehydes similarly as the Grignard reagents to form primarily the expected alcohols. In the presence of acetic anhydride, the alcohol is converted to the corresponding olefin, predominantly with Z configuration. In the case of benzaldehyde, Z- and E- 2-chloro-l-phenyl-3,3,3-trifluoropropene are the products H and I [114]. 

Acetic formic anhydride has been prepared by the reaction of formic acid with acetic anhydride2 3 and ketene,4,5 and of acetyl chloride with sodium formate.6 The present procedure is essentially that of Muramatsu.6 It is simpler than others previously described and gives better yields. It is easily adapted to the preparation of large quantities, usually with an increase in yield. Acetic formic anhydride is a useful intermediate for the formyl-ation of amines,3,7 amino acids,8,9 and alcohols,2,10 for the synthesis of aldehydes from Grignard reagents,11 and for the preparation of formyl fluoride.12... 

By reaction of 3-thienyllithium with magnesium bromide, the Grignard reagent, free from entrainment Grignard reagent, was obtained,- which is useful for the preparation of 3-acetothiophene by reaction with acetic anhydride at — and for the preparation... 

Dimethylaniline (bp 193°) is occasionally used as a solvent for the preparation of Grignard reagents. The main impurity is monomethyl-aniline, which may be removed by treatment with a small amount of acetic anhydride. The presence of secondary amine is indicated by a temperature rise on addition of acetic anhydride, and in the absence of this impurity, the solution process is endothermic. 

Acetylenic ketones can be prepared in moderate yield by the reaction of acetylenic Grignard reagents with acid chlorides or anhydrides [Eq. (41) 75-78]. Alkynyl magnesium chloride reacts with acetic anhydride to give acetylenic ketones in good yield (see Table 4, entry 17). 

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