Acetic anhydride-Boron trifluoride etherate

ACETYLATION Acetic anhydride-Boron trifluoride etherate Alumina. 

C-19 methyl migration occurs in the presence of acetic anhydride-boron trifluoride etherate. Prolonged hydrolysis, followed by selective reacetylation of the C-3 hydroxyl and Jones oxidation, yielded the cucurbitone (48). 

Related Reagents. Boron Trifluoride-Acetic Acid Boron Trifluoride-Acetic Anhydride Boron Trifluoride Etherate Boron Trifluoride Dimethyl Sulfide Tetrafluoroboric Acid. 

Cleavage of aliphatic ethers occurs with the reaction of acetic anhydride, boron trifluoride etherate, and lithiumbromide (eq 46). The ethers are cleaved to the corresponding acetoxy compounds contaminated with a small amount of unsaturated product. In some cases, the lithium halide may not be necessary. 

A cyclopropyl ketone is subject to homoconjugate addition using acetic anhydride/boron trifluoride etherate. Upon acetate addition, the enol is trapped as its enol acetate (eq 53). ... 

Isopropenyl acetate is converted into the dimethylketal of acetone (2,2-dimethoxy-propane) by treatment with mercuric acetate and boron trifluoride etherate.2 Elimination of the elements of methanol by reaction with acetic anhydride and pyridine give isopropenyl methyl ether. 

Thiele reaction Acetic anhydride. Acetic phosphoric anhydride. Boron trifluoride etherate. 

The desired elimination predominated only when the 3a-6romo-compound (55) was reduced with zinc, giving the 19-acetoxy-2-ene (56). A 3-oxo-2jS, 19-ether is opened by acetic anhydride-boron trifluoride to give the 2o,19-diacetoxy-ketone. Inversion at C-2 may occur either through nucleophilic attack of... 

The dimethyl acetal (94) is readily prepared from the 22-aldehyde (93) by direct reaction with methanol in the presence of hydrogen chloride. Ena-mines (95) are formed without a catalyst even with the poorly reactive piperidine and morpholine.Enol acetates (96) are prepared by refluxing with acetic anhydride-sodium acetate or by exchange with isopropenyl acetate in pyridine.Reaction with acetic anhydride catalyzed by boron trifluoride-etherate or perchloric acid gives the aldehyde diacetate. 

Boron trifluoride etherate in benzene converts A -20-acetoximinosteroids to the 17-ketones in somewhat lower yield, but the reaction of A -20-oximino steroids with this catalyst in the presence of acetic anhydride does not give the expected product two different compounds have been isolated and identified. ... 

Benkeser et a/.431 measured the relative rates of acetylation of alkylferrocenes using acetic anhydride catalysed by boron trifluoride etherate, in dichloromethane at 0 and 25 °C. The relative reactivities are given in Table 115, and are interesting... 

Nakagome and co-workers effected the successful cyclization of N-ethyl-N-arylaminomethylenemalonates (749) in poly phosphoric acid, prepared from orthophosphoric acid and phosphorus pentoxide in polyphosphate ester (PPE), prepared from phosphorus pentoxide and anhydrous diethyl ether in chloroform in phosphoryl chloride on the action of boron trifluoride etherate on the action of acetic anhydride and concentrated sulfuric acid or on the action of phosphorus pentoxide in benzene [71GEP2033971, 71JHC357 76JAP(K) 18440]. Depending on the work-up process, l-ethyl-4-oxoquinoline-3-carboxylates (750, R1 = Et), l-ethyl-4-oxoquinoline-3-carboxylic acids (750, R2 = H) and 3-ethoxycarbonyl-4-chloroquinolinium iodides (751) were obtained. Only the cyclization of... 

The material is prepared by acetylation of diisoamylene with acetic anhydride or acetyl chloride under boron trifluoride etherate catalysis [23a]. 

Treatment of chromium (III) acetylacetonate with acetic anhydride and boron trifluoride etherate yielded a complex mixture of acetylated chelates but very little starting material. Fractional crystallization and chromatographic purification of this mixture afforded the triacetylated chromium chelate (XVI), which was also prepared from pure triacetylmethane by a nonaqueous chelation reaction (8, 11). The enolic triacetylmethane was prepared by treating acetylacetone with ketene. The sharp contrast between the chemical properties of the coordinated and uncoordinated ligand is illustrated by the fact that chromium acetylacetonate does not react with ketene. 

Mercury salts, such as mercury(II) acetate,521-525 mercury(II) oxide,524,526-528 metcury(II) trifluoroace-tate,529,530 mercury(II) sulfate524,531 and mercury(II) phosphate531 catalyze the addition of carboxylic acids to alkynes. Acetic anhydride in the presence of boron trifluoride etherate can also be effectively used in this reaction (equation 292).521,522 Alkynoic acids undergo mercury-catalyzed cyclization to lactones (equation 293).523,532,533... 

The acylating reagent may be an acid chloride or an acid anhydride. Symmetrical ketones (—CH2 R = R2) yield only a single regioisomer. Thus acetone or cyclohexanone may be acylated with acetic anhydride in the presence of boron trifluoride-etherate to pentane-2,4-dione and 2-acetylcyclohexanone respectively (Expt 5.102). Both diketones are present in the reaction mixture as boron difluoride complexes [(10) and (11) respectively], from which they may be released by treatment with sodium acetate. Pentane-2,4-dione is appreciably water soluble and is isolated by means of its characteristic copper complex (12). 

Alternatively, direct electrophilic acylation of a BIPS also occurred in the 3-position. Vilsmeier formylation of 6-nitroBIPS gave 22% of the 3-formyl derivative (113, R=H) acetic anhydride with boron trifluoride etherate in chloroform solvent gave 56% of the 3-acetyl compound (113, R=Me) and benzoyl chloride with aluminium bromide in carbon disulfide solvent gave 26% of 3-benzoyl-6-nitroBIPS (113, R=Ph). None of the 3-acyl BIPS showed any coloration upon UV irradiation in any solvent.106... 

The reaction of linalool with boron trifluoride etherate has been re-examined no pinenes or camphene were obtained.146 Dehydrolinalool reacts with methyl iso-propenyl ether under acidic conditions by Claisen rearrangement to give the allene (58).147 Further papers in this section include reaction of monoterpenoid alcohols with paraformaldehyde-acetic anhydride-sodium acetate,148 rearrangement of the alcohol (47 X = OH) to the oxabicycloheptane (59) and the ketone (60),149 and the rearrangement of a typical monoterpenoid vicinal hydroxy-ester to an epoxide.150... 

Ethers Aluminum chloride-Sodium iodide. Aluminum iodide. Bis(isopropylthio)boron hromide. Boron trichloride. Boron trifluoride etherate. Bromotrimethylsilane. 2-Chloro-1,3,2-dithioborolane. Chlorotri-methylsilane-Acetic anhydride. Chlorotri-methylsilane-Sodium iodide. Dimethyl-boron bromide. Pyridinium p-toluenesulfo-nate. Sodium methaneselenolate. 

An A-ray structural analysis of one of the products obtained from thujopsene on treatment with peroxyacetic acid has been used to confirm the structure as (140). For reasons which are not immediately obvious thujopsene has been oxidized with a variety of metal acetates in acetic acid (e.g. Pb ", Tl Co , and Mn ). There is no apparent rationale for the different types of products formed and indeed there is some inconsistency of results between the two papers. " Dihydromayurone (141), on treatment with boron trifluoride etherate in acetic acid-acetic anhydride at different temperatures, gives rise to the five rearranged acetates (142)—(146). ... 

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