Trifluoromethylation of Carbonyl Compounds With Trifluoromethylzinc Iodide Under Ultrasonic Irradiation

Kitazume, Tomoya; Ishikawa, Nobuo

doi:10.1246/cl.1981.1679

Cited by 69 publications

(5 citation statements)

References 3 publications

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“…We found that cyclopropanation occurs readily with ordinary zinc and the preparation of zinc-copper couples could be avoided (15). Recently other workers reported similar observations using mossy zinc (20), and Kitazume and Ishikawa have shown that the reactions of zinc with perflouroalkyl iodides are also accelerated by ultrasonic waves (21).…”

Section: /C~c\supporting

confidence: 55%

Synthesis with ultrasonic waves

Boudjouk¹

1986

J. Chem. Educ.

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The pioneering work on the chemical applications of ultrasound (I) was conducted in the 1920's by Richards and Loomis in their classic survey of the effects of high-frequency sound waves (>280 kHz) on a variety of solutions, solids, and pure liquids (2). These studies showed that ultrasound accelerates a broad ranee of transformations such as the dispersion of mercury, th;: degassing of liquids, the explosion of nitrogen triiodide, the flocculation of silver chloride, the depression of the boiling temperatures of liquids, the hydrolvsis of dimethvlsulfate, and the iodine clock reaction.-In spite of the diversity of the chemical effects of ultrasonic waves discovered by Richards and Loomis, research since then has been sparse and uneven. For the most part, the emphases have heen on inorganic reactions, in particular aqueous solutions, and in nearly all cases the systems were homogeneous. Also, the sonicators used by the various research erouns were often auite different in confieuration and -.delivered differenr frequencies, intensities,and wattages.To comolirate the matter further. little was known of the roleoi thesk variables in affecting reaction rates. As a result, there are few generalizations upon which a new investigator can rely, and sonochemistry, in particular preparative sonochemistry, must he considered an area that is in its earliest stages and in need of much further study.One of the points on which there is general agreement is that, in order to produce a chemical effect in liquids using ultrasonic waves, sufficient energy must he imparted to the liquid to cause cavitation, i.e., the formation and collapse of bubbles in the solvent medium and the consequent release of enerw. When ultrasonic waves are oassed through a medium, i i e particles experience oscillati'ons that l e a l t o regions of compression and rarefaction. The negative pressure in the rarefaction region gives rise to the formation of bubbles, that mav he filled with a eas. the vapor of the liauid, or may he almost empty depenbing on the pressure a n d the forces holdina the liauid together.strictly defined, cavitation refers only t o the completely evacuated bubble or cavitv, a true void, hut, since dissolved gases are present unless Special steps are taken to remove themand, since thevapor of the liquid can also penetrate the cavity, the term cavitation most often encompasses the three kinds of bubbles.The collapse of these bubbles, caused by the compression region of the ultrasonic wave, produces powerful shock waves that are resoonsible for well-known processes such as cleaning, dispersion, and the erosion of metals. The energy output in the reaion of the collapsine bubble is considerable, . -with estimatesbf 2-3000°C and pressures in the kiloha; range for time Deriods in the nanosecond region (3). In summary, the cavitation process generates a transitory highenergy environment. These forces are responsible for the well-known commercial processes of ultrasonic cleaning, dispersion, and pasteurization as well as the efficiency of u...

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Section: /C~c\supporting

confidence: 55%

Synthesis with ultrasonic waves

Boudjouk¹

1986

J. Chem. Educ.

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“…Synthesis of 1 ,butan-2-ol. This trifluoromethyl alcohol was synthesized from [1-13C]hydrocinnamaldehyde according to the procedure of Kitazume and Ishikawa (1981). The labeled hydrocinnamaldehyde was prepared as follows: (2-phenylethyl)magnesium bromide was prepared from (2-bromoethyl)benzene and magnesium turnings in dry ether.…”

Section: Methodsmentioning

confidence: 99%

Complex of .alpha.-chymotrypsin and N-acetyl-L-leucyl-L-phenylalanyl trifluoromethyl ketone: structural studies with NMR spectroscopy

Liang¹,

Abeles²

1987

Biochemistry

166

160

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A dipeptidyl trifluoromethyl ketone, N-acetyl-L-leucyl-L-[1-13C]phenylalanyl trifluoromethyl ketone, was synthesized. This compound inhibits chymotrypsin with Ki = 1.2 microM [Imperiali B., & Abeles, R.H. (1986) Biochemistry 25, 3760-3767]. The complex formed between this inhibitor and alpha-chymotrypsin was examined with 1H, 13C, and 19F NMR spectroscopy to establish its structure in solution. The keto group of the trifluoro ketone is present as an ionized hemiketal group as deduced from the comparison of its 13C chemical shift with those of model hemiketals. The pKa of the hemiketal hydroxyl in the complex is approximately 4.9, which is about 4.2 units lower than the pKa of model hemiketals. This observation provides direct evidence that serine proteases are able to stabilize the oxyanions of tetrahedral adducts. Evidence is also presented for the presence of an Asp-His H bond and protonation of the imidazole group of His-57 in the tetrahedral adduct. The pKa of His-57 is higher than 10. This observation directly indicates that the pKa of His-57 is elevated in a complex containing a tetrahedral adduct.

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“…Secondary carbinols, obtained by the addition of vinyl organometallics to trifluoroacetaldehyde [59] or perfluoroalkyl organometallics to unsaturated aldehydes (Scheme 22) [60][61][62] can be oxidized by Dess-Martin [63,64] or Swern [65] reagents or using MnO 2 [66] in dichloromethane to the α,β-ethylenic trifluoromethyl ketones in good yields. [66,67] It should be noted that the reduction of acetylenic CF 3 ketones using LiAlH 4 or NaBH 4 does not give CF 3 enones but the corresponding allyl alcohols [50,64,68].…”

Section: Scheme 21mentioning

confidence: 99%

Preparation of α,β-Unsaturated Ketones Bearing a Trifluoromethyl Group and Their Application in Organic Synthesis

1997

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Trifluoromethylation of Carbonyl Compounds With Trifluoromethylzinc Iodide Under Ultrasonic Irradiation

Abstract: The trifluoromethylation of carbonyl compounds with trifluoromethylzinc iodide, prepared from trifluoromethyl iodide with ultrasonically dispersed zinc, smoothly proceeded to give corresponding α-trifluoromethyl carbinols in good yields.

Cited by 69 publications

References 3 publications

Synthesis with ultrasonic waves

Synthesis with ultrasonic waves

Complex of .alpha.-chymotrypsin and N-acetyl-L-leucyl-L-phenylalanyl trifluoromethyl ketone: structural studies with NMR spectroscopy

Preparation of α,β-Unsaturated Ketones Bearing a Trifluoromethyl Group and Their Application in Organic Synthesis

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