Claude Chavis

Isotactic Glycero Oligothymidylate. a Convenient Preparation of (R) and (S) 1′, 2′-Seco 2′-Nor Thymidine

Abstract (R) and (S) dimethoxytrityl derivatives of 1′, 2′-seco 2′-nor thymidine were synthesized in an efficient way. Isotactic dodecaoligoglycerothymidylate was obtained by a solid support phosphoramidite approach. The lack of hybridization with poly rA makes this acyclooligonucleotide useless as antisense or sense agent.

SnCl4 versus TiCl4-mediated coupling between N-6-benzoyladenine and perbenzoylated 2-deoxypyranose: Application to the synthesis of certain homochiral acyclo and carboacyclonucleosides

Abstract 1,3,4-tri- 0 -benzoyl 2-deoxyribopyranose and persilylated N-6-benzoyladenine react in two different and regioselective ways according to the nature of the coupling reagent SnCl4 or TiCl4. The former Lewis acid gives rise to the anomeric mixture of N-9 nucleosides and the latter affords mainly 3′-deoxy 3′-(N-6-benzoyl-9-adenyl) glycals. These two series of derivatives constitute useful synthons for the preparation of homochiral acyclo and carboacyclonucleosides.

IMPROVED PROCEDURE FOR THE REGIOSPECIFIC SYNTHESIS OF 2'-DEOXYRIBONUCLEOSIDES

Abstract 2′-Deoxyribonucleosides are regiospecifically synthesized in high yields by catalyzing with KI-dibenzo-18-crown-6 PTC the condensation between unprotected silylated purines and pyrimidines and the appropriate easily available 2-deoxyribofuranosyl or pyranosyl sugar derivatives.

Efficient synthesis of 1,2-seco and 1,2-seco 2-nor pyrimidine and purine nucleosides

Unprotected silylated purines and pyrimidines (adenine, guanine, cytosine, thymine) reacted with acetoxymethyl ether (acyclic sugar analogues) under solid PTC conditions, using KI and dibenzo-18-crown-6 in benzene-acetonitrile (1:1, v/v) to give regiospecifically the corresponding N-9 purine and N-1 pyrimidine acyclic nucleosides in fairly good yields.

Synthesis of racemic carboacyclonucleosides derived from butane-1, 4-diol and hexane-1, 6-diol

Abstract The synthesis of racemic diethyl succinate and dimethyl adipate substituted in their 2 and 3 position respectively by usual heterocyclic bases are described via the Michael addition of nucleobases on diethyl maleate and dimethyl (E)-3-hexene-1, 6-dioate. The Michael adducts are further reduced to afford the corresponding carboacyclonucleosides.

An Expeditious Synthesis of Homochiral (R) 2-(9-Purinyl)butane-1, 4-Diols from (S) Butane-1, 2, 4-Triol

Abstract The synthesis of (R) 2-(9-adenyl) and (R) 2-(9-guanyl)butane-1, 4-diols are described via an alkylation reaction of 6-chloropurine and N 2-acetyl-O6-diphenylcarbamoyl guanine by (S) 1, 4-di-tert-butyldiphenylsilyloxybutane-2-ol under Mitsunobu conditions.

Regio- and stereospecificity in radical cascade cyclizations of TMS-alcyne containing allyl bromomethyldimethylsilyl ethers

Abstract Tandem radical cyclization of (E) and (Z) TMS-homopropargyl allyl bromomethyl-dimethylsilyl ethers is reported to provide an all- cis substituted vinylcyclopentanol 5 . Regio- and stereospecificity are discussed.

The Benzyloxycarbonyl Protective Group : a Good Alternative to the Benzyl Protective Group in the Glycopyranoside and Glycofuranoside Series

Abstract A procedure for the O-benzyloxycarbonylation of secondary alcohols in the glucose, galactose, mannose, ribose and deoxyribose series is described. Starting from the (4-methoxy)tritylated derivatives on the primary hydroxyl group, the fully protected compounds were obtained for the first time in high yields.

Convenient Synthesis of (±)1′, 2′-Seco-2′, 3′-Methanonucleosides

Abstract The racemic 1′,2′-seco-2′,3′-methanonucleosides have been synthesized by a five step chemical sequence. In this way (±)-1-[(1′-hy-droxy-3′,4′-methylene-but-2′-oxy)methyl]cytosine 6c , thymine 6a , and uracil 6e and (±)-9-[(1′-hydroxy-3′,4′-methylene-but-2′oxy)methyl]adenine 6d and guanine 6b have been obtained and their antiviral evaluation is reported

New Acyclic β-Functionnalized (E) Allyl Alcohols and their Bromomethyldimethylsilyl Ethers as Cyclopentanoids Precursors

Abstract The syntheses of new acyclic (E) allyl alcohols β-functionnalized by various radical trapping functions and their corresponding bromomethyl-dimethylsilyl ethers are reported.