Synthesis of new cytotoxic aminoanthraquinone derivatives via nucleophilic substitution reactions

Aminoanthraquinones were successfully synthesized via two reaction steps. 1,4-Dihydroxyanthraquinone (1) was first subjected to methylation, reduction and acylation to give an excellent yield of anthracene-1,4-dione (3), 1,4-dimethoxyanthracene-9,10-dione (5) and 9,10-dioxo-9,10-dihydroanthracene-1,4-diyl diacetate (7). Treatment of 1, 3, 5 and 7 with BuNH2 in the presence of PhI(OAc)2 as catalyst produced seven aminoanthraquinone derivatives 1a, b, 3a, and 5a–d. Amination of 3 and 5 afforded three new aminoanthraquinones, namely 2-(butylamino)anthracene-1,4-dione (3a), 2-(butylamino)anthracene-9,10-dione (5a) and 2,3-(dibutylamino)anthracene-9,10-dione (5b). All newly synthesised aminoanthraquinones were examined for their cytotoxic activity against MCF-7 (estrogen receptor positive human breast) and Hep-G2 (human hepatocellular liver carcinoma) cancer cells using MTT assay. Aminoanthraquinones 3a, 5a and 5b exhibited strong cytotoxicity towards both cancer cell lines (IC50 1.1–13.0 µg/mL)

Synthesis of novel β-aminocyclobutanecarboxylic acid derivatives by a solvent-free aza-Michael addition and subsequent ring closure

Novel beta-aminocyclobutanecarboxylic acid derivatives were prepared via a sequential solvent-free aza-Michael addition of benzophenone imine across 3-halopropylidenemalonates and base-induced ring closure. These highly substituted cyclobutanedicarboxylic acid derivatives were subjected to a reactivity study which demonstrated the tendency of these donor-acceptor substituted four-membered rings to be converted into their corresponding ring-opened products

1,3-Dibenzyl-1H-anthra[1,2-d]imidazole-2,6,11(3H)-trione

The mol­ecule of the title compound, C29H20N2O3, contains four fused rings, three are six-membered rings and one is the five-membered imidazole ring. The fused-ring system is linked to two benzyl groups. The four fused rings are folded around the O=C⋯C=O direction of the anthraquinone, with a dihedral angle of 16.36 (8)° between the two terminal rings (A and D). The imidazole ring (D) is almost perpendicular to the two benzyl groups (E and F) with dihedral angles of 86.69 (17) and 83.15 (13)°, respectively. In the crystal, adjacent mol­ecules are linked by inter­molecular C—H⋯O hydrogen bonding

X=Y–ZH compounds as potential 1,3-dipoles. Part 64: Synthesis of highly substituted conformationally restricted and spiro nitropyrrolidines via Ag(I) catalysed azomethine ylide cycloadditions

1,3-Dipolar reactions of imines of both acyclic and cyclic α-amino esters with a range of nitroolefins using a combination of AgOAc or Ag2O with NEt3 are described. In most cases the reactions were highly regio- and stereospecific and endo-cycloadducts were obtained in good yield. However, in a few cases the initially formed cycloadducts underwent base catalysed epimerisation. The stereochemistry of the cycloadducts was assigned from NOE data and established unequivocally in several cases by X-ray crystallography

Straightforward synthesis of 2- and 2,8-substituted tetracenes

A simple regiospecific route to otherwise problematic substituted tetracenes is described. The diverse cores (E)- 1,2-Ar1CH2(HOCH2)C=C(CH2OH)I (Ar1 = Ph, 4-MePh, 4-MeOPh, 4-FPh) and (E)-1,2-I(HOCH2)C=C(CH2OH)I, accessed from ultra-low cost HOCH2C?CCH2OH at multi-gram scales, allow the synthesis of diol libraries (E)-1,2- Ar1CH2(HOCH2)C=C(CH2OH)CH2Ar2 (Ar2 = Ph, 4-MePh, 4-iPrPh, 4-MeOPh, 4-FPh, 4-BrPh, 4-biphenyl, 4-styryl; 14 examples) by efficient Negishi coupling. Copper-catalysed aerobic oxidation cleanly provides dialdehydes (E)-1,2- Ar1CH2(CHO)C=C(CHO)CH2Ar2 which in many cases undergo titanium(IV) chloride induced double Bradsher closure providing a convenient method for the synthesis of regiochemically and analytically pure tetracenes (12 examples). The sequence is typically chromatography-free, scalable, efficient and technically simple to carry out