Conversion of 2-deoxy-D-ribose into 2-amino-5-(2-deoxy-beta-D-ribofuranosyl)pyridine, 2'-deoxypseudouridine, and other C-(2'-deoxyribonucleosides)

Total synthesis of pseudouridineviaHeck-typeC-glycosylation

Pseudouridine (1) was synthesized by functional group interconversions of the Heck adduct11from 2,4-dimethoxy-5-iodopyrimidine (8) and ribofuranoid glycal4.

Discovery of a Novel, Isothiazolonaphthoquinone-Based Small Molecule Activator of FOXO Nuclear-Cytoplasmic Shuttling

FOXO factors are tumour suppressor proteins commonly inactivated in human tumours by posttranslational modifications. Furthermore, genetic variation within the FOXO3a gene is consistently associated with human longevity. Therefore, the pharmacological activation of FOXO proteins is considered as an attractive therapeutic approach to treat cancer and age-related diseases. In order to identify agents capable of activating FOXOs, we tested a collection of small chemical compounds using image-based high content screening technology. Here, we report the discovery of LOM612 (compound 1a), a newly synthesized isothiazolonaphthoquinone as a potent FOXO relocator. Compound 1a induces nuclear translocation of a FOXO3a reporter protein as well as endogenous FOXO3a and FOXO1 in U2OS cells in a dose-dependent manner. This activity does not affect the subcellular localization of other cellular proteins including NFkB or inhibit CRM1-mediated nuclear export. Furthermore, compound 1a shows a potent antiproliferative effect in human cancer cell lines.

Synthesis of peptide nucleic acids containing pyridazine derivatives as cytosine and thymine analogs, and their duplexes with complementary oligodeoxynucleotides

Synthesis of peptide nucleic acids (PNAs) is reported with new pyridazine-type nucleobases: 3-aminopyridazine (aPz) and 1-aminophthalazine (aPh) as cytosine analogs, and pyridazin-3-one (Pz(O)) and phthalazin-1-one (Ph(O)) as thymine analogs. The PNAs having an aPz or a Pz(O) formed duplexes with each complementary oligodeoxynucleotide forming a base pair with G or A, respectively, as evaluated by using UV melting analyses and circular dichroism (CD) spectra.

A general and efficient synthesis of pyridin-2-yl C-ribonucleosides bearing diverse alkyl, aryl, amino, and carbamoyl groups in position 6

An efficient and practical methodology of preparation of 6-substituted pyridin-2-yl C-ribonucleosides was developed. A one-pot two-step addition of 2-lithio-6-bromopyridine to TBS-protected ribonolactone followed by acetylation gave 1beta-(6-bromopyridin-2-yl)-1-O-acetyl-2,3,5-tri-O-(tert-butyldimethylsilyl)-D-ribofuranose in high yield. Its reduction with Et(3)SiH and BF(3) x Et(2)O afforded the desired TBS-protected 6-bromopyridine C-ribonucleoside as pure beta-anomer in good overall yield of 63%. This intermediate was then subjected to a series of palladium catalyzed cross-coupling reactions, aminations and aminocarbonylations to give a series of protected 1beta-(6-alkyl-, 6-aryl-, 6-amino-, and 6-carbamoylpyridin-2-yl)-C-ribonucleosides. Deprotection of silylated nucleosides by Et(3)N x 3HF gave a series of title free C-ribonucleosides (12 examples).

Modular synthesis of 5-substituted thiophen-2-yl C-2'-deoxyribonucleosides

A new modular methodology of preparation of 5-substituted thiophene-2-yl C-nucleosides was developed. A Friedel-Crafts-type of C-glycosidation of 2-bromothiophene with toluoyl-protected methylglycoside 2 gave the desired protected 1beta-(5-bromothiophen-2-yl)-1,2-dideoxyribofuranose 4a in 60%. The key intermediate 4a was then subjected to a series of palladium-catalyzed cross-coupling reactions. The cross-coupling reactions with alkyl organometallics gave beta-(5-alkylthiophen-2-yl)-2-deoxyribonucleosides 4 and 7 in moderate yields accompanied by side-products of reduction. On the other hand, cross-couplings with arylstannanes proceeded smoothly to give a series of beta-(5-arylthiophen-2-yl)-2-deoxyribonucleosides 4 in good yields. Deprotection of toluoylated nucleosides by NaOMe in MeOH and silylated nucleosides by Et 3N.3HF gave a series of free C-nucleosides 6. Alternatively, other types of 5-arylthiophene C-nucleosides 6 were prepared in one step by the aqueous-phase cross-coupling reactions of unprotected 1beta-(5-bromothiophen-2-yl)-1,2-dideoxyribofuranose with boronic acids. Title 5-arylthiophene C-nucleosides 6 exhibit interesting fluorescent properties with emission maxima varying from 339 to 396 nm depending on the aryl group attached.

A metallo base-pair incorporating a terpyridyl-like motif: bipyridyl-pyrimidinone.Ag(I).4-pyridine

The design and characterization of a geometrically unique, metallo base-pair motif is reported.

Modular and Practical Synthesis of 6-Substituted Pyridin-3-yl C-Nucleosides

A novel modular and practical methodology for preparation of 6-substituted pyridin-3-yl C-nucleosides was developed. The Heck reaction of 2-chloro-5-iodopyridine with a 3'-TBDMS-protected glycal gave a 6-chloropyridin-3-yl nucleoside analogue, which was then desilylated, selectively reduced, and reprotected to give the TBDMS-protected 6-chloropyridin-3-yl C-2'-deoxyribonucleoside as a pure beta-anomer in a total yield of 39% over four steps. This key intermediate was then subjected to a series of palladium-catalyzed cross-coupling reactions, aminations, and alkoxylations to give a series of protected 1beta-(6-alkyl-, 6-aryl-, 6-hetaryl, 6-amino-, and 6-tert-butoxypyridin-3-yl)-2'-deoxyribonucleosides. 6-Unsubstituted pyridin-3-yl C-nucleoside was prepared by catalytic hydrogenation of the chloro derivative and 6-oxopyridine C-nucleoside by treatment of the 6-tert-butoxy derivative with TFA. Deprotection of all the silylated nucleosides by Et3N.3HF gave a series of free C-nucleosides (10 examples).

New Modular and Efficient Approach to 6-Substituted Pyridin-2-yl C-Nucleosides

A novel modular, efficient, and practical methodology of preparation of 6-substituted pyridin-2-yl C-nucleosides was developed. An addition of 2-lithio-6-bromopyridine 2b to TBDMS-protected 2-deoxyribonolactone 5 gave aduct 7 as an equilibrium mixture of anomeric hemiketals 1-(6-bromopyridin-2-yl)-1-hydroxynucleosides 7a,b and its open form 7c. Reduction of the adduct 7 with Et3SiH and BF3 x Et2O afforded the desired 6-bromonucleoside 8a as pure beta-anomer in a total yield of 32% over two steps from 5. Intermediate 8a was then subjected to a series of palladium catalyzed cross-coupling reactions and aminations to give a series of protected 1beta-(6-alkyl-, 6-aryl-, and 6-aminopyridin-2-yl)-2-deoxyribonucleosides 9. Catalytic hydrogenation of 8a gave an unsubstituted pyridine C-nucleoside, and diazotative oxodeamination of 6-aminopyridine nucleoside 9f by isopentyl nitrite in acetic acid gave 6-oxopyridine nucleoside 10i. Deprotection of silylated nucleosides 9 by Et3N.3HF gave a series of free C-nucleosides 10.

Chemo- and Regioselective Functionalization of Uracil Derivatives. Applications to the Synthesis of Oxypurinol and Emivirine

[reaction: see text] A novel route for the synthesis of 4,5-difunctionalized uracils using a chemo- and regioselective bromine/magnesium exchange reaction on 5-bromo-4-halogeno-2,6-dimethoxypyrimidines has been developed. Applications to the synthesis of pharmaceuticals such as oxypurinol and emivirine are reported.