Tosylhydrazones acetals

Interesting stereochemical aspects of the protic Bamford-Stevens reactions of the epimeric 7-oxohexa-hydrocannabinol tosylhydrazone acetates (70) and (72) have been recently demonstrated. When the axial epimer (70) was added to sodium ethylene glycol, the ring expansion product (71) was obtained in 38% yield. On the other hand, reaction of the equatorial epimer (72) under the same conditions yielded (73) in 56% yield (equations 45 and 46). Notably, the aprotic Bamford-Stevens reaction of the axial epimer (70) gave rise to (73) (30-40% yield) after acetylation. 

The following general procedure has been used for the reduction of the tosylhydrazone derivatives of various steroidal ketones. A mixture of the tosylhydrazone (50 mg) and sodium borodeuteride (50 mg) in dry dioxane (3 ml) is heated under reflux for 2 hr, and then the excess deuteride is decomposed by the addition of a few drops of acetic acid. Ether is added and the resulting solution is washed with 2 N sodium bicarbonate solution and... 

In keto steroids the reductions were also achieved by electrolysis in 10% sulfuric acid and dioxane using a divided cell with lead electrodes (yields 85-97%) [862], hy specially activated zinc dust in anhydrous solvent (ether or acetic anhydride saturated with hydrogen chloride) (yields 50-87%) [155, 86J], and by the above mentioned reduction of tosylhydrazones with sodium borohydride (yields 60-75%) [811]. 

Another route that has been recommended recently is oxidation of the As-stenyl acetate to the corresponding 7-kctone, conversion to the p-tosylhydrazone, and elimination with lithium hydride. Overall yields are in the range 20-50%.2... 

Diketopyrrolizine 281 can be converted to a number of derivatives of the C-2 carbonyl group these include the oxime (282a), the acetate (282b), and the tosylhydrazone (282c). From the oxime (282a), a series of derivatives of the... 

An alternative procedure is to convert the carbonyl compound into the toluene-p-sulphonylhydrazone,12 followed by reduction with either sodium borohydride in acetic acid,13 or with catecholborane, followed by decomposition of the intermediate with sodium acetate or tetrabutylammonium acetate.14 The former method is illustrated by the conversion of undecan-6-one into undecane (Expt 5.6), and the latter by the conversion of acetophenone into ethylbenzene (Expt 6.4, Method B). A feature of these methods is that with a, / -unsaturated ketones, migration of the carbon-carbon multiple bond occurs thus the tosylhydrazone of isophorone gives 3,3,5-trimethylcyclohex-l-ene, and the tosylhydrazone of oct-3-yn-2-one gives octa-2,3-diene. 

To a 10-mL round-bottomed flask fitted with a nitrogen balloon was added sulfide catalyst (0.2 equiv), anhydrous dioxane (4.0 mL), rhodium(II) acetate dimer (2 mg, 0.01 equiv), substrate (0.5 mmol), benzyl triethylammonium chloride (23 mg, 0.2 equiv), and tosylhydrazone sodium salt (1.5 equiv). The reaction mixture was stirred vigorously at 40 °C for 48 h. Work-up consisted of the sequential addition to the reaction mixture of water (5 mL) and ethyl acetate (5 mL). The aqueous layer was washed with ethyl acetate (2.5 mL) and the combined organic phases dried (MgSC ), filtered, and concentrated in vacuo. The crude products were analyzed by aH NMR to determine the diastereomeric ratio, and then purified by FC to afford the corresponding cyclopropane. 

Oximes, Tosylhydrazones, and Related Derivatives.—Ketoximes afford enimides in refluxing acetic anhydride-pyridine.181 Theproduct (207) from 5a-cholestan-3-one oxime (206), for example, gave 3-acetylamino-5a-cholest-2-ene (208) in 93% yield after chromatography on alumina. Use of succinic instead of acetic anhydride, with pyridine, gave the enimide (209) which was stable to chromatography. A radical mechanism is proposed. Reduction of ketoximes by Cr11, V11, or Tiin salts in acetic anhydride affords the same enamides, by acetylation of the intermediate imines. The... 

Halogenated pyridazinones have been thus prepared from muco-chloric acid (35) 286,312-316 mucobromic acid, or the related chlorobromo acid. Instead of hydrazine semicarbazide can be used and the intermediate semicarbazone cyclized in hot acetic acid, loss of the carbamide group taking place simultaneously. Acid hydrazides likewise form hydrazones first, which cyclize with the aid of phosphorus oxychloride. Tosylhydrazones are reported to cyclize easily. ... 

N,N-Methyltosylhydrazones. Ketones react only slowly with N,N-methyl-tosylhydrazine (1) but hydrazones of this type can be prepared by N-alkylation of tosylhydrazones with phase-transfer catalysis. The more reactive thioketones also react sluggishly with 1, but in this case, the reaction can be catalyzed by soft Lewis acids. Thus the reaction of 2 with 1 proceeds in high yield at room temperature in the presence of 1 equiv. of silver nitrate. Mercuric acetate also promotes this reaction, but the yield of 3 is only 50% because of formation also of 4 in 44% yield. 

This salt is superior to sodium acetate in the reduction of tosylhydrazones with catecholborane (6, 98 7, 54). The efiect results from the increased solubility in organic solvents. ... 

Ketones - Nitriles/ Ketones can be converted into nitriles by way of the tosyl-hydrazones. Thus the tosylhydrazone of cyclohexanone (I) on treatment with potassium cyanide in methanol acetic acid at room temperature followed by addition o( 2N... 

Table 7 Reduction of Carbonyl Tosylhydrazones with Sodium Borohydride in Acetic Acid...

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