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A novel metal-free reduction system, in which H

Michael addition of indole and pyrrole to a variety of α, β-unsaturated ketones was efficiently promoted by a catalytic amount of GaCl3 in aqueous media to afford the corresponding products in good to excellent yields.

A series of unreported chiral β-carbolines 4 with trifluoromethyl group at position-1 and chiral carboxamide chains or amino acid ester chains at position-3 has been designed and synthesized. The results of bioassay in vitro show that compounds 4e, 4i and 4k show 78.8%, 84.0% and 78.9% inhibition on monoamine oxidase, in 1 mmol/L, respectively, and compound 4e also exhibit 60.9% inhibitory activity on tumor lung cell A-549 in 10−5 mmol/L. In view of different configuration, the inhibitory activity on monoamine oxidase of S-enantiomer of the target compound is better than that of R-enantiomer.

In the title compound, 2C2H8N+·C10H4O8 2−·2C12H8N2, dimethylammonium cations, 2,5-dicarboxybenzene-1,4-dicarboxylate anions and 1,10-phenanthroline molecules are linked by N—H...N and N—H...O hydrogen bonds into a network structure. The 2,5-dicarboxybenzene-1,4-dicarboxylate anion lies on an inversion center.

The title compound, C18H16N2OS, crystallizes in a triclinic unit cell with two independent mol­ecules in the asymmetric unit. Intermolecular N—H⋯S, C—H⋯O and C—H⋯S hydrogen bonds link the mol­ecules into ribbons, which form stacks with short intra- and intermolecular S⋯C [3.385 (5) A] and C⋯O′ [3.162 (5) A] contacts.

Michael addition of indole and pyrrole to a variety of α, β-unsaturated ketones was efficiently promoted by a catalytic amount of GaCl3 in aqueous media to afford the corresponding products in good to excellent yields.

Wenzhou Vocational and Technical College, Wenzhou, Zhejiang 325035, P. R. China E-mail : djc@wzvtc.cn Fax : 86-577-86680188 College of Chemistry and Materials Science, Wenzhou University, Wenzhou, Zhejiang 325027, P.R. China E-mail : hywu3@163.com Fax : 86-577-88368280 Manuscript received 15 February 2007. revised 28 December 2007, accepted 6 March 2008 Diethyl acetals were obtained from carbonyl compounds in good to excellent yields under mild reaction conditions in the presence of triethyl orthoformate and a catalytic amount of gallium triiodide in anhydrous ethanol.

Department of Chemistry. Wenzhou Normal College, Wenzhou 325027, P. R. China E-mail : hywu3@ 163.com Fax : 86-577-88339081 Department of Chemistry, Zhejiang University (Campus Xixi), Hangzhou 310028, P.R. China Manuscript received 6 May 2002.accepted 6 September 2002 Oxazolidinones were synthesized in high yields via cycloaddition of epoxides with isocyanates catalyzed by samarium triiodide.

In the title compound, C11H14N4OS·H2O, the dihedral angle between the ethoxy­benzene group and the triazole ring is 48.20 (8)°. Inter­molecular N—H⋯O and O—H⋯N hydrogen bonds involving the water mol­ecules form a chain along the a axis.

The title compound, C30H28NO3P, containing four planar ring systems, exists in the Z form. Short intra­molecular C⋯O [2.697 (3) A] and C⋯N [3.049 (4) A] contacts may indicate the presence of weak intra­molecular hydrogen bonds.

In the title compound, 5-methyl-2,6-dioxo-1,2,3,6-tetra­hydro­pyrimidine-3-acetic acid, C7H8N2O4, the planar carboxy­methyl moiety makes a dihedral angle of 83.89 (6)° with the thymine heterocycle plane. O—H⋯O, N—H⋯O, C—H⋯O and C—H⋯π interactions are observed in the structure, leading to the formation of a three-dimensional network.

In the title compound, C11H14N4O4, the ethyl acetate portion of the organic mol­ecule is nearly planar and makes a dihedral angle of 74.55 (6)° with the plane of the theobromine heterocycle. The crystal structure is stabilized by inter- and intramolecular C—H⋯O hydrogen bonds and intermolecular C—H⋯N hydrogen bonds.

In the title compound, C11H10N2O2, the benzene ring is almost perpendicular to the heterocycle; the dihedral angle is 91.2 (2)°. A chain structure is formed via an intermolecular N—H⋯O hydrogen bond.

In the title compound, C19H18N2O2, the two phenyl rings are located on the same side of the thymine ring, resembling the two front claws of a crab. The crystal structure involves some weak C—H⋯O interactions.