Product yields with temperature charcoal

Nitrilimines react with hydrazones of aliphatic aldehydes and ketones to yield addition products 9 which cyclise when treated with palladium charcoal at room temperature to give 1,6-dihydro-j-tetrazines 10 <96JCR(S)174>. 

V-(9-Fluorenylmethoxycarbonyl)-0-(2,3,4-tri-0-benzoyl- 3-D-xylopyranosyl)-L-serine 15. The Fmoc O-xylosyl serine benzyl ester 13 (1.0 g, 1.2 mmol) is stirred in methanol (40 mL) at room temperature and subjected to hydrogenolysis for 18 h under atmospheric pressure using palladium-charcoal (0.2 g, 5%) as the catalyst. The educt 13 dissolves slowly. The catalyst is filtered off, and the solvent evaporated in vacuo. If the residue is not pure according to thin-layer chromatography (TLC), it is dissolved in 2 mL of ethyl acetate and purified by chromatography on a short column of silia gel 60. The byproducts are eluted with petroleum ether-ethyl acetate the product 15 with methanol yield 0.85 (92%) mp 109°C, [cr]D -12.6° (c 0.3, CH3OH) Rf 0.64 (toluene-ethanol, 1 2). 

Sancycline (Ig) was dissolved in 25 ml trifluoroacetic acid, N-iodosuccinimide (1.2 eq) added, and the reaction stirred 40 minutes at 0 °C and 5 hours at ambient temperature. The mixture was concentrated, dissolved in 3 ml methyl alcohol, and precipitated in diethyl ether. The product was purified by treating with activated charcoal, filtering through celite, and isolated in 75% yield. H-NMR and MS data supplied. 

An 11,1 g (24.1 mmol) portion of the compound 160i,17a-cyciopentylidenedioxy-9a-fiuoro-11)3,21 -dihydroxy-1,4-pregnadiene-3,20-dione is placed in a 250 ml round-bottom flask. A 100 ml portion of pyridine is added and the mixture is stirred to a complete solution. A 5.5 ml (54.6 mmol) portion of acetic anhydride is added dropwise and the mixture is stirred for 2 A hours. An 11 mi portion of methanol is added and the mixture is stirred an additional hour. This mixture is concentrated under reduced pressure to about 10 to 15 ml and then poured slowly into a mixture of ice, water and dilute hydrochloric acid. This mixture is stirred and the solid which forms is collected by filtration, washed with water to a neutral pH and air dried yielding 11.5 g. This solid is taken up in hot acetone, treated with activated charcoal and filtered while hot through diatomaceous earth. The filtrate is concentrated on a steam bath while adding n-hexane to the point of incipient crystallization. This mixture is allowed to cool to room temperature. The solid which forms iscollected by filtration, washed with acetone-n-hexane (1 14) and air dried yielding 7.0 g of the desired product. 

The entire crude product is boiled gently with 300 ml Skellysolve B, cooled to room temperature, decanted from certain "gummy materiaV, treated with activated charcoal, concentrated to 100 ml, and allowed to crystallize. The product, thus obtained (10 g) is recrystallized from 50 ml of methanol and yields 4.5 g of anal3rtically pure material having mp 103-104°C. 

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