Rachid Benhida

A mild and effective iodination method using iodine in the presence of bis-(trifluoroacetoxy)iodobenzene

Abstract Herein is described a mild and effective iodination method using bis-(trifluoroacetoxy)iodobenzene-iodine as reagent to be applied to electron deficient heterocyclic systems (protected indoles, coumarin…) Moreover, sensitive protecting groups such as acetyl and tert-butyldimethylsilyl were found to be stable under the new iodination reaction conditions.

Incorporation of serinol derived acyclic nucleoside analogues into oligonucleotides: Influence on duplex and triplex formation

Abstract Phosphoramidites 6a-c were readily prepared by an original route and used to incorporate serinol derived units I–III in oligonucleotides which, compared to their natural analogues, exhibited a decreased htbridization capacity for duplex and triplex formation.

Incorporation of a novel nucleobase allows stable oligonucleotide-directed triple helix formation at the target sequence containing a purine·pyrimidine interruption

Thermal denaturation experiments have established that an oligonucleotide incorporating the artificial nucleobase S, does form a stable triplex with a double stranded DNA which exhibits a pyrimidine interruption within the oligopurine sequence.

Synthesis of 6-allyl and 6-heteroarylindoles by palladium catalyzed Stille cross-coupling reaction

Several 6-allyl and 6-heteroarylindoles have been synthesized in high yield by means of palladium catalyzed cross-coupling reactions between tributyltin derivatives and 6-haloindoles to give useful intermediates for the synthesis of analogues of biologically active natural products.

Efficient stereocontrolled synthesis of 2-benzimidazolyl- and 2-indolyl-C-nucleosides

Abstract We report herein the synthesis of β-2-benzimidazolyl- and β-2-indolyl- C -nucleosides and their α-anomers in a stereoselective way. The stereocontrol was observed either in the reduction step (hemiacetal to diol) of the protected heterocycles ( 1b – d ), or in the intramolecular Mitsunobu cyclisation of the free heterocyclic diols obtained from the hemiacetals 1a and 1e .

First total synthesis of fungerin an antifungal alkaloid from Fusarium sp.

Abstract The first total synthesis of fungerin 1 , a new antifungal alkaloid, is described. Starting from a 4,5-diiodoimidazole derivative, the procedure involves regioselective prenylation and Heck type reaction steps to give 1 in high yield.

N-Trifluoroacétylation sélective d'ortho-arylènediamines sous ultrasons

Abstract Mono and di-N-trifluoroacetylation of ortho-arylenediamines can be performed selectively under ultrasound irradiation according to the relative amounts of starting materials. Mono and di-trifluoroacetylated compounds 3 and 4 are prepared with good yields in dry THF during 1 to 2 min sonication.

NMR recognition studies of C·G base pairs by new easily accessible heterobicyclic systems

Abstract Recognition of DNA duplexes by triplex forming oligonucleotides (TFO) is limited to DNA homopurine sequences. As a first step to overcome this limitation we report here NMR recognition studies of the C·G base pair by new heterocyclic systems, derived from benzimidazole and benzoxazole units bearing an urea donor moiety, designed to bound to the 4-amino group of the cytosine and the O4- and N7-atoms of the guanosine bases, respectively.

NOVEL 2'-DEOXYCYTIDINE ANALOGUES AS PH INDEPENDENT SUBSTITUTES OF PROTONATED CYTOSINES IN TRIPLE HELIX FORMING OLIGONUCLEOTIDES

Abstract The N-acetyl derivatives 1a and 2a of the aminotriazole and aminoimidazole 2′-deoxynucleosides 1 and 2 were synthesized as potential substitutes of protonated 2′-deoxycytidines within triple helix forming oligonucleotides for their recognition of DNA duplexes in a pH independent manner.

Selective N1-Alkylation of Pyrimidine Bases via Radical (SRN1) Mechanism

Abstract Under photostimulated SgNl conditions the cytosine nitranion behaves as a nucleophile toward the carbon radical generated from gem halonitro, or gem dinitroalcane derivatives to give regiospecifically the N-1 alkyled cytosine compound which is representative of a new series of cytosine acyclonucleosides. Uracile and its 5-fluoro or 5-nitro analogs fail to react and thymine gives an unexpected disubstituted SgNl product whose formation is discussed.