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Starting from ethyl (1 S,4 R)-4-hydroxy-2-methylcyclopent-2-ene-1-carboxylate,as a common enantiopure building block readily obtained by enzymatickinetic resolution of the corresponding racemic derivative, 3′-methylcarbovir,3′-methylabacavir, and three modified analogues were synthesizedvia the linear construction of the purine heterocycles. These derivativeswere evaluated as potential agents against HIV-1, HIV-2, and otherimportant viral pathogens. None of the new compounds had significantantiviral activity at a concentration of 100 μg˙mL -¹ ,which was the highest concentration tested.

A series of 3'-methyl-branched and purine-modified analogues of aristeromycin were synthesized via the SN 2 displacement of a key triflate, which was prepared from a readily available enantiopure building block in eight steps. The synthesized compounds were evaluated as potential antiviral agents against important viruses. Only the 2,6-diaminopurine derivative exhibited moderate activity against vesicular stomatitis virus.

This paper describes the racemic and stereoselective synthesis of novel conformationally locked 3'-methyl-2',3'-oxiranefused carbocyclic nucleosides (nucleosides numbering). The key step is the direct coupling of an alcohol bearing the 1-methyl-6-oxabicyclo[3.1.0]hexane scaffold with diversely substituted purine nucleobases under Mitsunobu reaction conditions providing only the N 9 target molecules.

A convenient chemoenzymatic enantioconvergent access to enantiomerically pure (+)- or (-)-4-hydroxy-3-methyl-2-cyclohexenone is described using a one-pot two-step kinetic resolution-stereoinversion protocol followed by hydrolysis. The key step of the sequence is the spontaneous elimination of an undesired stereocenter. The choice between enzymatic acyl transfer or ester alcoholysis of the corresponding racemic starting material, together with the selectivity of a lipase, determines the absolute configuration of the desired single enantiomer.

An efficient enantioselective synthesis of fully-oxygen, ated Taxol® A-ring subunit has been achieved using (-)-karahana lactone, (-)-2, as an enantiopure starting building-block and a diastereoselective allylic hydroxylation as the key step.

Enantiopure ethyl (1 S,4 R)-4-hydroxy-2-methylcyclopent-2-ene-1-carboxylate, readily obtained by enzymatic kinetic resolution of the corresponding racemic derivative, provided a convenient starting building block for an 11-step chiral preparation of (-)-3′-methylaristeromycin with 23% overall yield.

An enantioselective synthesis of (+)-ricciocarpin A is described starting from (+)-karahana lactone as an enantiopure building block. This synthesis involves a stereofacially directed diastereoselective hydroboration for the installation of the required stereogenic center, and the efficient conversion of an intermediate hydroxyaldehyde to the one-carbon homologated cyanide, using the mild formation of a cyanohydrin followed by an one-pot two-step Barton-McCombie double deoxygenation sequence of the hydroxyl moieties.