Selective oxidation of betulin to biologically active betulinic aldehyde is demonstrated for the first time over Ru/C catalyst mixed with a basic hydrotalcite and using SiO 2 as a dehydrating agent in synthetic air at 108 8C in toluene with conversion of 41 % in 24 h and 67 % selectivity to betulinic aldehyde, whereas without SiO 2 with Ru/C the corresponding conversion and selectivity values were 20 % and 66 %, respectively. Over another, acidic Ru/C catalyst even higher conversion was achieved, giving, however, allobetulin as a main product. These results indicate that basicity and absence of water are crucial for selective botulin oxidation over Ru catalysts. The conversion levels are comparative with the results in the oxidation of hydroxymathylfurfural, which contains a hydroxymethyl group attached to the heterocyclic ring.Pharmaceuticals are conventionally synthesized in multistep procedures using several organic solvents and stoichiometric reagents, therefore the E-factor, i. e. the amount of waste per formed product is very high. [1] Currently there is a high interest to develop more environmentally friendly methods for production of pharmaceuticals, moreover starting the synthesis from naturally occurring compounds. A potential compound for medical applications is betulin, which is present in the bark of some tree species, such as Betula sp. [2,3] Betulinic acid is present in birch bark or cork of cork oak (Quercus suber L.) and can be isolated and extracted, [2] whereas the stem bark of Tectona grandis contains betulinic aldehyde. [4] In this work betulin oxi-dation was investigated using heterogeneous catalysts and air as an oxidant (Figure 1).Oxidation of betulin produces both betulonic and betulinic aldehydes and acids, respectively, as products ( Figure 1). Betulinic acid has been conventionally prepared from betulin in socalled Jones oxidation process using Cr 2 O 3 as an oxidant. The formed betulonic acid can be reduced to betulinic acid with NaBH 4 in tetrahydrofuran. [18] Betulinic acid was also synthesized via oxidation of betulin using Keggin type tungstophosphoric acid together with potassium dichromate between 15-35 8C during 60 to 240 min giving betulonic acid, which is reduced to betulinic acid with NaBH 4 in an organic solvent. [19] TEMPO (2,2,6,6-teramethylpiperidine -oxyl) catalyst has also been used in the oxidation of betulin to betulinic acid with iodine or (diacetoxyiodo)benzene DIB as oxidants. 2 Furthermore, a high isolated yield of betulinic acid (86 %) was achieved, using 4-acetamido-TEMPO as a catalyst together with NaClO 2 /NaOCl at 50 8C. [20] The above-mentioned betulin derivatives exhibit several biological and medicinal properties. [5][6][7][8][9][10][11][12][13][14][15][16][17] Several examples were given from betulin oxidation with homogeneous catalysts, e. g. RuCl 2 (PPh 3 ) 3 and TEMPO as a cocatalyst in oxygen at 1 atm and 105 8C giving 15 % yield of betulinic aldehyde at 17 % conversion in 27 h and in 8 h at 100 8C under 8 bar 69 % of betulinic aldehyde, respectively...