Wojciech Sas

Synthesis of (±)-branched-chain azaisonucleosides via Michael addition of 5-nitro-2,2-pentamethylene-1,3-dioxane to methyl 2-bromoacrylate

Michael reaction of 2,2-pentamethylene-5-nitro-1,3-dioxane 1 with methyl 2-bromoacrylate, generated in situ from methyl 2,3-dibromopropanoate and triethylamine, afforded α-bromo-γ-nitroester 3, which was readily converted into various 5,5-bis(hydroxymethyl)pyrrolidine analogues of nucleosides.

Preparation of highly substituted 7-oxa-1-azabicyclo[2.2.1]heptanes from 4-nitro-1-butene derivatives. Route to polysubstituted piperidines

Abstract 4-Nitro-1-butene derivatives 2 readily available from the palladium(0)-catalyzed C-allylation of nitroalkanes were converted into highly substituted 7-oxa-1-azabicyclo[2.2.1]heptane derivatives 6 in three steps including an intramolecular 1,3-dipolar cycloaddition reaction. Catalytic hydrogenolysis of the N–O bond in 6 afforded polysubstituted 4-hydroxypiperidines.

Synthesis and Antiviral Properties of Aza-Analogues of Acyclovir

Aza-analogues of Acyclovir were obtained from N-(2-pivaloyloxyethyl)-N-(pivaloyloxymethyl)-p-toluenesulfonamide via a one-pot base silylation/nucleoside coupling procedure. The antiviral activities of all aza-nucleosides in vitro against a variety of viruses were evaluated. None of these compounds displayed any specific antiviral effects.

Synthesis of Novel AZA-Analogues of Tiazofurin with 2-[5,5-bis(Hydroxymethyl)Pyrrolidin-2-yl] Framework as Sugar Mimic

The novel aza-analogues of tiazofurin (TZF) with 2-[5,5-bis(hydroxymethyl)pyrrolidin-2-yl] moiety, as sugar mimic, were synthesized from O,O-cyclohexylidene derivative of 4,4-bis(hydroxymethyl)-4-nitrobutanal in multi-gram scale. The synthetic route consisted of three stages: (i) the synthesis of corresponding derivative of 5,5-bis(hydroxymethyl)pyrrolidine-2-carbonitrile, (ii) the construction of ethyl thiazole-2-carboxylate part by the conversion of the pyrrolidine-2-carbonitrile into the N-trifluoroacetyl derivative followed by cyclocondensation with L-cysteine ethyl ester and then by dehydrogenation, and (iii) the final transformation of the ethyl thiazole-4-carboxylate into the aza-analogues of TZF. The TZF aza-analogues were evaluated for their antiviral activities in cell-culture-based assays.

Asymmetric synthesis of a branched-chain analogue of azapyranoses from a 5-allylic derivative of 5-nitro-1,3-dioxane. Synthesis of (3R,4S)-6,6-bis(hydroxymethyl)-3,4-dihydroxypiperidin-2-one

Abstract Methyl 4-(5-nitro-1,3-dioxaspiro[5.5]undecan-5-yl)but-2-enoate 2 , obtained from the palladium(0)-catalyzed reaction of a salt of 5-nitro-1,3-dioxane 1 with methyl γ-bromocrotonate, was converted into the title piperidinone (ee 78%) in three steps.

Synthesis of branched-chain azafuranose derivatives from secondary nitroalkanes. Facile synthesis of (±) 4-amino-4,4-bis(hydroxymethyl)-4-deoxythreonic-1,4-lactam

Abstract The title branched-chain threonic-1,4-lactam 6 was smoothly prepared in four steps from readily available 2,2-dimethyl-5-nitro-1,3-dioxane 2 .

Asymmetric synthesis of novel polyhydroxylated derivatives of indolizidine and quinolizidine by intramolecular 1,3-dipolar cycloaddition of N-(3-alkenyl)nitrones

Reaction of 3-O-benzyl-1,2-O-isopropylidene-1,5-pentadialdo-α- D-xylofuranose with N-(1,1-dimethylbut-3-enyl)hydroxylamine followed by intramolecular 1,3-dipolar cycloaddition yields 7-oxa-1-azabicyclo[2.2.1]heptane derivative 4, which is easily converted into novel polyhydroxylated quinolizidine 6 and indolizidine 8.