Acetone tosylhydrazone

When flexible molecules (or flexible ligands in coordination networks) are employed, different network architectures may be generated from the same building blocks. An analogy can be drawn to conformational polymorphism such as that seen in acetone tosylhydrazone, 4. A monoclinic and a triclinic form are obtained from anhydrous ethanol, sometimes together. The conformations differ by about 15° about the S-C exocyclic bond. 

Cu(N03)2, Bentonite, hexane, acetone, 60-97% yield." When silica gel is used as the support, tosylhydrazones and thioketals are also cleaved in excellent yield."... 

Zr(03PCH3), 2(03PC6H4S03H)o8, acetone, water, reflux 30 min-24 h, 70-95% yield. Semicarbazones, tosylhydrazones, and hydrazones are also cleaved."... 

Titanium silicate molecular sieves not only catalyze the oxidation of C=C double bonds but can be successfully employed for the oxidative cleavage of carbon-nitrogen double bonds as well. Tosylhydrazones and imines are oxidized to their corresponding carbonyl compounds (243) (Scheme 19). Similarly, oximes can be cleaved to their corresponding carbonyl compounds (165). The conversion of cyclic dienes into hydroxyl ketones or lactones is a novel reaction reported by Kumar et al. (165) (Scheme 20). Thus, when cyclopentadienes, 1,3-cyclohexadiene, or furan is treated with aqueous H202 in acetone at reflux temperatures for 6 h in the presence of TS-1, the corresponding hydroxyl ketone or lactone is obtained in moderate to good yields (208). 

Regeneration of ketones from tosylhydrazones with Oxone in acetone has been reported. Under controlled pH (pH = 6) the reaction gave very high yield (90%) of the product. In this paper we demonstrated that the use of in situ formed dimethyldioxirane under controlled pH conditions gives better results (equation 66). 

S. Phenyldiazomethane (Vacuum pynolyzxa method). In a 200-mL, singlenecked, round-bottomed flask is placed 13.71 g (0.05 mol) of benzaldehyde tosylhydrazone. A 1.0 M solution (51 mL) of sodium methoxide in methanol (0.051 mol) (Note 2) is added via syringe and the mixture is swirled until dissolution is complete (Note 3). The methanol is then removed by rotary evaporator. The last traces of methanol are removed by evacuation of the flask at 0.1 mm for 2 hr. The solid tosylhydrazone salt is broken up with a spatula and the flask is fitted with a vacuum take-off adaptor and a 50-mL receiver flask. The system is evacuated at 0.1 nm and the receiver flask is cooled in a dry ice-acetone bath to about -50°C. The flask containing the salt is immersed in an oil bath and the temperature is raised to 90°C (use a safety shield). At this temperature, red phenyldiazomethane first begins to collect in the receiver flask. The temperature is raised to 220°C over a 1-hr period (Note 4). During this time red phenyldiazomethane collects in the receiver flask (Note 5). The pressure increases to 0.35 mm over the course of the pyrolysis. On completion of the pyrolysis the pressure drops to less than 0.1 mm. 

A simple, high yielding (65-90%) procedure has been described for the preparation of medium ring and macrocyclic acetylenic lactones which is mechanistically related to the well known Eschenmoser fragmentation reaction, and the following example is representative. Bromination of the tosylhydrazone of 1 was carried out with NBS at -10°C in a water/t-butanol/acetone mixture. The reaction mixture was then treated with aqueous NaHSC>3 solution and the resulting mixture heated at 50-60°C for one hour, which gave the acetylenic lactone 2. 

Aldehydes and ketones can be regenerated from their tosylhydrazones by treatment with N-bromosuccinimide/CH3OH/acetone [49] or with H202/K2C03 [50], The mechanism of the first conversion is given in Scheme VIII/15. 

Tosylhydrazones (191) from unsymmetrical ketones in this case 2-butanone, by reaction with an alkyllithium reagent gave regioselective formation of the tosylhydrazone dianion. The latter, by subsequent treatment with acetone, affords the p-hydroxytosylhydrazone (192), which with more alkyllithium gives the homoallylic alcohol (193) (Scheme 78). 

Cleavage of tosylhydrazones, arylhydrazones, and oximes to their parent ketones simply by exchange in acetone is said to offer a mild and convenient method under non-acidic conditions. Hexadeuterioacetone affords a-deuteriated ketones. Although tosylhydrazones of saturated ketones are reduced by borohydride in methanol to give hydrocarbons, similar treatment of the tosylhydrazone of cholest-4-en-3-one gave a mixture of 3a- and 3/S-methoxycholest-4-enes, apparently through a diazonium alkoxide ion pair. The reduction of tosylhydrazones of... 

In neutral media, they leave carbonyl derivatives intact but reduce tosylhydrazones to the corresponding hydrocarbons under reflux of CHCI3 (Section 3.3.4). This reduction is compatible with a-enone, epoxide, or lactone groups present in the molecule [GL3]. In cold acetone, these reagents reduce acid chlorides to aldehydes [FHl] (Section 3.2.7). In the presence of Lewis acids or gaseous HCl in CHjClj, they reduce aldehydes and ketones. The selective reduction of aldehydes in the presence of ketones can also be realized (Section 3.2.1). These reagents also reduce aromatic azides to amines (Section 5.2). 

Regioselective formation of the tosylhydrazone dianion was observed in tosylhydrazones of the type 111 derived from unsymmetrical ketones such as 2-butanone. Abstraction of protons from the less hindered side of 111 and subsequent reaction with acetone gave a / -hydroxytosylhydrazone, which on treatment with alkyllithium gave the homoallylic alcohol 112 in good yield as shown in equation 58s 3. Another example is shown in equation 59. 

Cieavage of tosylhydrazones. Carbonyl compounds can be regenerated in high yield (80-957 ) from tosylhydrazones by exchange with aqueous acetone in the presence of distilled BF3 etherate (20°, 6-18 hours). The paper reports 25 luccessful experiments. 

A soln. of cyclohexanone tosylhydrazone in acetone heated 24 hrs. at 65° in a sealed glass tube cyclohexanone. Y 78%. F. e., also cleavage of phenyl-, 2,4-dinitrophenyl-hydrazones, and oximes, and a-perdeuteriated ketones with acetone d(j, s. S. R. Maynez, L. Pelavin, and G. Erker, J. Org. Chem. 40, 3302 (1975). 

Cleavage of tosylhydrazones. A mixture of phenylacetone tosylhydrazone and Am-berlyst 15 in 10 1 acetone/water stirred at room temp, for 24 h phenylacetone. Y 91%. The method is applicable to aldehydes (especially in the presence of 10 eqs. of paraformaldehyde) as well as ketones it is simple and cheap furthermore, acid-sensitive groups such as furyl derivs., esters or ethers are not affected. F.e. incl. cleavage of oximes, 2,4-dinitrophenylhydrazones and semicarbazones, s. R. Ballini, M. Petrini, J. Chem. Soc. Perkin Trans. I 1988, 2563-5. 

Boron fluoride acetone Oxo compds. from tosylhydrazones by interdiange with acetone Mild non-redox method... 

Regeneration of ketones from tosylhydrazones, aryl hydrozones, and oximes by exchange with acetone. 

A reaction tube was charged with 2-dicyclohexylphosphino-2, 4, 6 -triisopropylbiphenyl (XPhos) (19.1 mg, 4.00 pmol, 4 mol%), tris(dibenzylidene-acetone)dipalladium(O) (9.16 mg, 5.00 pmol, 1 mol%), lithium rer/-butoxide (202 mg, 2.40 mmol), the tosylhydrazone (1.1 mmol), and dioxane (4 mL). After 1 min, the aryl halide (1 mmol) was added. The system was heated at 110°C with stirring and reflux. When the reaction was completed, the crude reaction mixture was allowed to cool to ambient temperature, taken up in dry pentane, hexanes or dichloromethane (15 mL), and filtered through celite. The solvents were evaporated under reduced pressure, and the residue was purified by flash chromatography on silica gel. ... 

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