Synthesis of new 2′, 3′-modified uridine derivatives from 2′,3′-ene-2′-phenylselenonyl uridine by Michael addition reactions

Modern Synthetic Strategies with Organoselenium Reagents: A Focus on Vinyl Selenones

In recent years, vinyl selenones were rediscovered as useful building blocks for new synthetic transformations. This review will highlight these advances in the field of multiple-bond-forming reactions, one-pot synthesis of carbo- and heterocycles, enantioselective construction of densely functionalized molecules, and total synthesis of natural products.

Synthesis of Oxazolidin-2-ones by Oxidative Coupling of Isonitriles, Phenyl Vinyl Selenone, and Water

Reaction of alkyl isocyanides, phenyl vinyl selenone, and water in the presence of a catalytic amount of Cs2 CO3 afforded oxazolidin-2-ones in good yields. This unprecedented heteroannulation process created four chemical bonds in a single operation with the isocyano group acting formally as a polarized double bond and phenyl vinyl selenone as a latent 1,3-dipole. The phenylselenonyl group played a triple role as an electron-withdrawing group to activate the 1,4-addition, a leaving group, and a latent oxidant in this transformation.

Methyl-α-D-2-selenonyl Pent-2-enofuranoside: A Reactive Selenosugar for the Diversity Oriented Synthesis of Enantiomerically Pure Heterocycles, Carbocycles, and Isonucleosides

The construction of vinyl selenone on a furanoside led to a highly reactive synthetic intermediate methyl-α-D-2-selenonyl pent-2-enofuranoside composed of a masked aldehyde, an electron-deficient double bond along with an excellent leaving group. This new Michael acceptor on reactions with different nucleophiles afforded bicyclic azasugars, cyclopropanated carbohydrate, dihydrofuran- and dihydroisoxazole- substituted furanosides, and isonucleosides in moderate to good yields. Hydrolysis of the hemiacetal linkage of some of these modified carbohydrates afforded enantiopure aziridines, nitrocyclopropane, and dihydrofuran.

Triple role of phenylselenonyl group enabled a one-pot synthesis of 1,3-oxazinan-2-ones from α-isocyanoacetates, phenyl vinyl selenones, and water

Reaction of α-substituted α-isocyanoacetates with phenyl vinyl selenones in the presence of a catalytic amount of base (DBU or Et3N, 0.05-0.1 equiv) followed by addition of p-toluenesulfonic acid (PTSA, 0.1-0.2 equiv) afforded 4,4,5-trisubstituted 1,3-oxazinan-2-ones in good to excellent yields. Enantiomerically enriched heterocycles can also be prepared using a Cinchona alkaloid-derived bifunctional organocatalyst for the Michael addition step. The phenylselenonyl group served as an activator for the Michael addition, a leaving group and a latent oxidant in this integrated reaction sequence.

Enantiopure 1,4,5-trisubstituted 1,2,3-triazoles from carbohydrates: applications of organoselenium chemistry

A wide range of stable vinyl selenone-modified furanosides has been synthesized for the first time. These 2π-partners undergo 1,3-dipolar cycloaddition reactions with a wide range of organic azides to afford enantiopure trisubstituted triazoles. Furanosyl rings opened up during triazole synthesis to generate polyfunctionalized molecules, ready to undergo further transformations. This strategy is one of the most convenient methods for the synthesis of enantiopure 1,4,5-trisubstituted 1,2,3-triazoles where the chiral components are attached to C-4 or C-5 position of triazole ring. These triazoles are formed in a regioselective manner, and several pairs of regioisomeric triazoles have also been synthesized. The approach affords densely functionalized triazoles, which are amenable to further modifications because of the presence of aldehyde and hydroxyl groups. This powerful and practical route adds to the arsenals of chemists and biologists interested in the synthesis and applications of triazoles.

Unusual olefin formation by PhSe-F trans-elimination

A new approach to the synthesis of 2',3'-didehydro-2',3-dideoxynucleosides was described in excellent yield through unusual olefin formation by PhSe-F trans-elimination.

Efficient Synthesis of 2‘,3‘-Dideoxy-2‘-amino-3‘-thiouridine

[reaction: see text] Metal ion rescue experiments provide a powerful approach to establish the presence and role of divalent metal ions in the biological function of RNA. The utility of this approach depends on the availability of suitable nucleoside analogues. To expand the range of this experimental strategy, we describe the first synthesis of 2',3'-dideoxy-2'-amino-3'-thiouridine (12) in 19.5% overall yield starting from 2,2'-anhydrouridine (1).

An efficient synthesis of a new series of acyclonucleosides starting from beta-amino alcohols

A series of new acyclonucleosides analogues 3 has been synthesized very efficiently in three steps starting from beta-amino alcohols 1. The key step of this process is a nucleophilic substitution with various nucleophiles on 2,2'-anhydronucleosides 2. The chemo- and stereoselectivities of this reaction are discussed. AM1 calculations sustained the observed chemoselectivity.