Tosyl with sodium/ethanol

Saunders and co-workers (Amin et al., 1990) used E2 elimination reactions in the p-substituted 2-phenylethyl system to test the new criteria for tunnelling suggested by the above calculations. The actual substrates and base/solvent systems they used were (2-phenylethyl-2-f)-trimethylammonium bromide, [19], with sodium ethoxide in ethanol, 2-phenylethyl-2-f bromide, [20], with potassium t-butoxide in t-butyl alcohol and 2-(p-chlorophenyl)ethyl-2-f tosylate, [21], with potassium t-butoxide in t-butyl alcohol. When equation (57) was applied to the experimental secondary (kB/ S) KIEs in Table 39, the calculated /th h KIEs were 1.106 0.033 and 1.092 0.026 for [19] and [21],... 

The synthetic utility of the chloral ene adducts has been extensively explored. Reaction with NaOR in ROH gives the a-alkoxy ester with inversion of configuration. Reaction of the corresponding tosyl-ate with sodium ethoxide in ethanol affords ethyl alka-2,4-dienoates (Scheme 9). 

Menthol and neomenthol have the structures I and II, respectively, and differ only in the configuration of the hydroxyl. When they are converted to their tosylates and the latter are treated with sodium ethoxide in ethanol, the following reactions occur predominantly. 

Alkylation of the enolate of (138) with methallyliodide gave the product (149) whose stereochemistry was assigned on the basis of equilibration experiment. It was converted to the dione (150) by oxidation with osmium tetrooxide and sodiumperiodate. The aldol cyclization of (150) effected with sodium hydride and trace of t-amyl alcohol in refluxing benzene afforded the enone (151) in 88% yield. Normal protic conditions (sodium hydroxide, ethanol) were not effective in this transformation. All attempts for its conversion to aphidicolin (148) by intermolecular additions proved fruitless and therefore were turned to intramolecular methods. Molecular models show clearly that the top face of the carbonyl group is less hindered to nucleophilic attack than is the bottom face. Thus the reduction of (151) with lithium aluminium hydride afforded the alcohol (152) whose vinyl ether (153) was subjected to pyrolysis for 2 hr at 360 C in toluene solution containing a small amount of sodium t-pentoxide to obtain the aldehyde (154) in 69% yield. Reduction and then tosylation afforded the alcohol (155) and tosylate (156) respectively. Treatment of this tosylate with Collman s reagent [67] (a reaction that failed in the model system) afforded the already reported ketoacetonide (145) whose conversion to aphidicolin (148) has been described in "Fig (12)". 

Toluenesulphonamido)phenyl] ethyl 2,3,4-tri-(9-benzyl-Q -D-gluco-pyranoside has been condensed with 2,3,4-tri-0-benzyl-6-0-(7V-phenyl-carbamoyl)-l-0-tosyl-D-glucopyranose to yield 2,4-(4-toluene-sulphonamido)-phenyl ethyl 2,3,4,2, 3 4 -hexa-0-benzyl-6 -<9-(7V-phenylcarbamoyl)-a-isomalto-side. The disaccharide was decarbanilated in ethanol with sodium ethoxide. The sequence of coupling with the 1-O-tosyl-D-glucose derivative followed by decarbanilation was repeated to form the tri- and tetra-saccharide derivatives. 

Preparation by tosylation of 2,4,6-trihydroxy-phenyl benzyl ketone with p-toluenesulfonyl chloride in the presence of potassium carbonate in refluxing acetone for 4 h, followed by melhylation with dimethyl sulfate (reflux 30 h) and final detosylation with refluxing ethanolic sodium hydroxide for 45 min (19%) [5335]. 

Lithium chloride, preferably dissolved in absolute ethanol, has also been used306 419 420 for preparing alkyl chlorides. Dissolved in absolute ethanol-acetone (1 1, by vol.), it has recently414 found application with alditol sulfonates. Its action on l,4 3,6-dianhydro-2,5-di-0-mesyl-L-iditol, l,4 3,6-dianhydro-2,5-di-0-mesyl-D-mannitol, and l,4 3,6-dian-hydro-2,5-di-0-mesyl- (and -2,5-di-O-tosyl-) sorbitol resembles the action of sodium iodide on these compounds, i.e., the first displays no appreciable reaction, the second gives the 2,5-dichloro-2,5-dideoxy derivative, and the last two afford the respective monochloromonodeoxy-mono-O-sulfonyl derivatives. Treatment of l,4 3,6-dianhydro-2,5-di-0-mesyl-sorbitol during 48 hours at 180-90° gives some of a dianhydro-mono-chloromonodeoxy-sorbitoleen. 

An oven-dried 300-ml flask, equipped with a side-arm fitted with a silicone rubber septum, a magnetic stirrer bar, and a reflux condenser connected to a mercury bubbler, is cooled to room temperature under a stream of dry nitrogen. Tetrahydrofuran (20 ml) is introduced, followed by 7.1 g (25 mmol) of cyclooctyl tosylate (1). The mixture is cooled to 0 °C (ice bath). To this stirred solution, lithium triethylborohydride (Section 4.2.49, p. 448) [33.3 ml (50 mmol) of a 1.5 m solution in tetrahydrofuran] is added, and the ice bath removed. The mixture is stirred for 2 hours (c. 25 °C). Excess hydride is decomposed with water. The organoborane is oxidised with 20 ml of 3 m sodium hydroxide solution and 20 ml of 30 per cent hydrogen peroxide [(2) and (3)]. Then the tetrahydrofuran layer is separated. The aqueous layer is extracted with 2 x 20 ml portions of pentane. The combined organic extracts are washed with 4 x 15 ml portions of water to remove ethanol produced in the oxidation. The organic extract is dried (MgS04) and volatile solvents removed by distillation (2). Distillation of the residue yields 2.27 g (81%) of cyclooctane as a colourless liquid, b.p. 142-146 °C, Wq0 1.4630. 

N,N, N",N "-Tetra(p-toluenesulfonyl) Derivative of f 13]aneNA. Two equivalents of sodium ethoxide (3.02 g in 66 mL of ethanol) are added to SO g of the tosylated linear tetraamine in 200 mL of boiling ethanol. After the solution is boiled for 20 minutes, the ethanol is removed by rotary evaporating to dryness to yield the disodium salt of the tosylated linear tetraamine. The sodium salt is dissolved in 660 mL of dimethylformamide (0.1 M) and transferred to a 2-L, three-necked flask equipped with an addition funnel and a thermometer. The mixture is heated to 110°, and 1 equiv of 1,3-dibromopropane (14 g in 330 mL of DMF, 0.2 M) is added dropwise over a period of 1 hour while the solution is stirred vigorously. The volume of DMF is reduced to one-fourth the initial volume. The solution is slowly added to a volume of water equal to 1 times that of the initial DMF volume. This yields a tacky off-white precipitate. The product is recrystallized from hot benzene. A white product is precipitated by reducing the volume of the benzene to about 150-mL, adding ethanol to the solution, and then letting it stand at room temperature for 1 hour. Yield 40%. 

---