Recent developments in the biotransformation of various compounds using microalgae

921-929Biotransformation, as one of the most important tools of green chemistry, is being increasingly used to obtain new products using plant cell cultures, fungi, algae and fresh cut vegetables under mild reaction conditions. Recently, various examples of the biotransformation of organic compounds are reported using microalgae. Herein we present a short review of the reaction of organic compounds in the presence of microalgae

Production of chiral aromatic alcohol by acetophenone and 1-arylethanol derivatives using vegetables

69-74We have studied the biotransformation of acetophenone derivatives (1a-1f) and 1-arylethanol derivatives (2a-2e, 2g, 2h) using various vegetables. It is found that the reduction of acetophenone derivatives (1a-1f) using carrot (Ducus carota) gives (S)-1-arylethanols with high enantioselectivity. On the other hand, biooxidation of 1-arylethanols (2a-2e, 2g, 2h) using potato (Solanum tuberosum) is oxidized to give (R)-1-arylethanols as major product with high stereoselectivity. Carrot (D. carota) is the best catalyst for this reduction and shows a good reaction yield and enatioselectivity. On the other hand, it is found that the racemic alcohols are converted into the corresponding (R)-alcohols with high ee using Japanese potato (S. tuberosum) as catalyst. The availability of the enzymatic system using various vegetables is convenient and an eco-friendly system

Synthesis of dihydro-1,4-thiazine from α-keto spiro-thiazolidine

1037-1041The reaction of α-bromocycloalkanone with 2-aminoethanthiol leads to the regioselective formation of spirothiazolidin-2-one with the oxo-group migrating to the original position occupied by the halogen atom. The reaction of 1-thia-4-azaspiro[4.5]alkan-6-one with bromine, iodine, copper (II) salts, acid or base gives dihydro-1,4-thiazine derivatives in moderate yields. Moreover, the treatment of the spiro-thiazolidine derivatives on silica gel under microwave gives the 1,4-thiazine compound

Biotransformation of steroidal compounds using Lignincola laevis

327-330Biotransformation of testosterone 1 and stanolone 2 has been investigated with fungus of Lignincola laevis. Biotransformaton of 1 gives 15α,17β-dihydroxyandrost-4-en-3-one 3. In the case of 2, two products, 5α-androstan-3α,17 β-diol 4 and 5α-androstane-3, 17-dione 5 have been obtained

The reaction of α-halocarbonyl compounds with (NH₄)OH, (NH₄)₂SO₄ or NH₄Cl solution under microwave-irradiation

1495-1502Reaction of α-halo ketone (α-bromo ketone) under microwave irradiation gives the pyrazine and quinoxaline derivative in good yields. This reaction affords a clean and convenient synthetic method for pyrazine and quinoxaline derivatives

A new alkoxy-, hydroxy- and nitratoiodination of α,β-unsaturated esters and amides using iodine-ammonium cerium (IV) nitrate and cerium (IV) sulfate

1503-1510The reactions of electron-deficient α,β-unsaturated esters using I2-ammonium cerium (IV) nitrate (CAN) or I2-cerium (IV) sulfate (CS) in alcohols (methanol, ethanol, or 1-propanol) under 50°C-reflux give the corresponding β-alkoxy-α-iodo esters in good yields. In the case of MeCN and MeCN-H2O, β-nitrato- and β-hydroxy-α-iodo compounds are obtained. The reaction of methyl acrylate (1), ethyl acrylate (2), ethyl crotonate (3), and ethyl methacrylate (4) using I2-CS give the corresponding β-hydroxy-α-iodo esters in good yields compared with those using I2-CAN