Synthesis of dipyrrolo[3,4-a:3,4-c]carbazole-1,3,4,6-tetraones bearing a sugar moiety

Anomeric modification of carbohydrates using the Mitsunobu reaction

The Mitsunobu reaction basically consists in the conversion of an alcohol into an ester under inversion of configuration, employing a carboxylic acid and a pair of two auxiliary reagents, mostly triphenylphosphine and a dialkyl azodicarboxylate. This reaction has been frequently used in carbohydrate chemistry for the modification of sugar hydroxy groups. Modification at the anomeric position, leading mainly to anomeric esters or glycosides, is of particular importance in the glycosciences. Therefore, this review focuses on the use of the Mitsunobu reaction for modifications of sugar hemiacetals. Strikingly, unprotected sugars can often be converted regioselectively at the anomeric center, whereas in other cases, the other hydroxy groups in reducing sugars have to be protected to achieve good results in the Mitsunobu procedure. We have reviewed on the one hand the literature on anomeric esterification, including glycosyl phosphates, and on the other hand glycoside synthesis, including S- and N-glycosides. The mechanistic details of the Mitsunobu reaction are discussed as well as this is important to explain and predict the stereoselectivity of anomeric modifications under Mitsunobu conditions. Though the Mitsunobu reaction is often not the first choice for the anomeric modification of carbohydrates, this review shows the high value of the reaction in many different circumstances.

Synthesis, checkpoint kinase 1 inhibitory properties and in vitro antiproliferative activities of new pyrrolocarbazoles

In the course of structure-activity relationship studies on granulatimide analogues, new pyrrolo[3,4-c]carbazoles have been synthesized in which the imidazole heterocycle was replaced by a five-membered ring lactam system or a dimethylcyclopentanedione. Moreover, the synthesis of an original structure in which a sugar moiety is attached to the indole nitrogen and to a six-membered D ring via an oxygen is reported. The inhibitory activities of the newly synthesized compounds toward checkpoint kinase 1 and their in vitro antiproliferative activities toward three tumor cell lines: murine leukemia L1210, and human colon carcinoma HT29 and HCT116 are described.

Synthesis, in vitro antiproliferative activities, and Chk1 inhibitory properties of pyrrolo[3,4-a]carbazole-1,3-diones, pyrrolo[3,4-c]carbazole-1,3-diones, and 2-aminopyridazino[3,4-a]pyrrolo[3,4-c]carbazole-1,3,4,7-tetraone

The synthesis of substituted pyrrolo[3,4-a]carbazole-1,3-diones, pyrrolo[3,4-c]carbazole-1,3-diones, and 2-aminopyridazino[3,4-a]pyrrolo[3,4-c]carbazole-1,3,4,7-tetraone is reported. Their inhibitory properties toward Checkpoint 1 kinase (Chk1) have been evaluated and their in vitro antiproliferative activities toward three tumor cell lines: murine leukemia L1210, human colon carcinoma HT29 and HCT116 have been determined. From the biological results, it appears that, in contrast with the upper E heterocycle, the lower D heterocycle is not absolutely required for Chk1 inhibition. The ATP binding pocket of Chk1 seems to be adaptable to substitution of the nitrogen of the imide E heterocycle with a hydroxymethyl group, allowing the fundamental hydrogen bond with the Glu(85) residue of the enzyme.

Synthesis and Cytotoxicity of Indolopyrrolemaleimides

A series of indolopyrrolemaleimides have been synthesized and evaluated for their cytotoxicity in vitro against human leukemia cell line and four human solid cancer cell lines. Some of the compounds showed high or mediate activity against the lines. 6dc is the most promising compound among them. The inhibition toward topoisomerase I was also studied.

Bis-imide granulatimide analogues as potent Checkpoint 1 kinase inhibitors

Granulatimide and isogranulatimide, natural products isolated from an ascidian, were found to be abrogators of the cell cycle G2-M phase checkpoint by inhibition of Checkpoint 1 kinase (Chk1). In the course of structure-activity relationship studies on granulatimide analogues, we have synthesized a series of bis-imides, in which the imidazole moiety was replaced by an imide heterocycle. Various modifications have been introduced on one or both imide heterocycles, on the benzene ring, and on the indole nitrogen. Moreover, aza bis-imide analogues were synthesized in which the indole moiety was replaced by a 7-azaindole. Compared to those of granulatimide and isogranulatimide, the Chk1 inhibitory activities of some of the bis-imide carbazoles were stronger. In particular, 1,3,4,6-tetrahydro-10-hydroxy-7H-dipyrrolo[3,4-a:3,4-c]carbazole-1,3,4,6-tetraone 11 exhibited an IC(50) value on purified full length Chk1 of 2 nM, which makes it a more potent Chk1 inhibitor than granulatimide and isogranulatimide. To get an insight into the selectivity of this new family of compounds, the inhibitory activities of 1,3,4,6-tetrahydro-7H-dipyrrolo[3,4-a:3,4-c]carbazole-1,3,4,6-tetraone A have been evaluated on a panel of 15 kinases, the strongest inhibitory potency was found for Chk1. The inhibitory activities of compounds A, 5 and 11 toward Src tyrosine kinase and the cytotoxicity of various tumor cell lines were also evaluated.

Synthesis and biological evaluation of new dipyrrolo[3,4-a:3,4-c]carbazole-1,3,4,6-tetraones, substituted with various saturated and unsaturated side chains via palladium catalyzed cross-coupling reactions

The syntheses of a series of dipyrrolo[3,4-a:3,4-c]carbazole-1,3,4,6-tetraones, substituted in 10-position with saturated and unsaturated side chains, via palladium catalyzed cross-coupling reactions, are described. These compounds can be considered as granulatimide bis-imide analogues. Their inhibitory activity toward Chk1 kinase and their antiproliferative activities in vitro in four tumor cell lines are reported.