1-C-phosphonomethyl- and 1-C-difluorophosphonomethyl-1,4-imino-l-arabinitols as Galf transferase inhibitors: A comparison

Tunable Approach to C-Linked Analogs of Glycosamines

The synthesis of (1R)-2-amino-2-deoxy-β-l-gulopyranosyl benzene and the α and β forms of 2-amino-2-deoxy-l-idopyranosyl benzene derivatives was accomplished through stereospecific addition of tributylstannyllithium to readily available (S_R)- or (S_S)-N-tert-butanesulfinyl-arabinofuranosylamine building blocks, followed by stereoretentive Pd-catalyzed Migita-Kosugi-Stille cross-coupling, stereoselective reduction, and an activation-cyclization strategy. Application of this methodology paves the way to new three-dimensional chemical space and preparation of unknown (non-natural) and complex 2-amino-2-deoxy sugars of biological interest.

2,3,5-Tri-O-benzyl-d-xylofuranose

The synthesis and crystallization of 2,3,5-tri-O-benzyl-d-xylofuranose permitted us to isolate the alpha anomer with a small contamination of the beta form (ca 10%), whose first crystallographic structure obtained in the P212121 space group was determined at 100 K up to a resolution of sin θmax/λ = 0.71 Å−1 and refined to an R1 value of 0.0171 with a Hirshfeld atom refinement (HAR) approach.

Stereoselective Synthesis of 1-C-Diethylphosphonomethyl and -difluoromethyl Iminosugars from Sugar Lactams

A strategy allowing the straightforward synthesis of 1-C-phosphonomethyl and 1-C-phosphonodifluoromethyl iminosugars is reported. Conversion of sugar lactams to the corresponding imines with Schwartz's reagent followed by their reaction with LiCH₂P(O)(OEt)₂ and LiCF₂P(O)(OEt)₂ stereoselectively afforded the 1,2-cis and 1,2-trans glycosyl phosphonates, respectively, in modest to good yields. Application of this methodology to C-2 orthogonally protected sugar lactams paved the way to 2-acetamido- and 2-deoxy-1-C-phosphonomethyl iminosugars.

Iminosugars as glycosyltransferase inhibitors

Iminosugars are naturally occurring carbohydrate analogues known since 1967. These natural compounds and hundreds of their synthetic derivatives prepared over five decades have been mainly exploited to inhibit the glycosidases, the enzymes catalysing the glycosidic bond cleavage, in order to find new drugs for the treatment of type 2 diabetes and other diseases. However, iminosugars are also inhibitors of glycosyltransferases, the enzymes responsible for the synthesis of oligosaccharides and glycoconjugates. The selective inhibition of specific glycosyltransferases involved in cancer or bacterial infections could lead to innovative therapeutic agents. The synthesis and biological properties of all the iminosugars assayed to date as glycosyltransferase inhibitors are reviewed in the present article.

Fluorinated carbohydrates as chemical probes for molecular recognition studies. Current status and perspectives

This review provides an extensive summary of the effects of carbohydrate fluorination with regard to changes in physical, chemical and biological properties with respect to regular saccharides. The specific structural, conformational, stability, reactivity and interaction features of fluorinated sugars are described, as well as their applications as probes and in chemical biology.

Synthesis, docking study and biological evaluation of ᴅ-fructofuranosyl and ᴅ-tagatofuranosyl sulfones as potential inhibitors of the mycobacterial galactan synthesis targeting the galactofuranosyltransferase GlfT2

A series of ten novel ᴅ-fructofuranosyl and ᴅ-tagatofuranosyl sulfones bearing a 1-O-phosphono moiety and three different substituents at C-2 has been prepared. Due to the structural similarities of these scaffolds to the native substrate of mycobacterial galactofuranosyltransferase GlfT2 in the transition state, we evaluated these compounds by computational methods, as well as in an enzyme assay for the possible inhibition of the mycobacterial galactan biosynthesis. Our data show that despite favorable docking scores to the active site of GlfT2, none of these compounds serve as efficient inhibitors of the enzymes involved in the mycobacterial galactan biosynthesis.

Biosynthesis of Galactan in Mycobacterium tuberculosis as a Viable TB Drug Target?

While target-based drug design has proved successful in several therapeutic areas, this approach has not yet provided compelling outcomes in the field of antibacterial agents. This statement remains especially true for the development of novel therapeutic interventions against tuberculosis, an infectious disease that is among the top ten leading causes of death globally. Mycobacterial galactan is an important component of the protective cell wall core of the tuberculosis pathogen and it could provide a promising target for the design of new drugs. In this review, we summarize the current knowledge on galactan biosynthesis in Mycobacterium tuberculosis, including landmark findings that led to the discovery and understanding of three key enzymes in this pathway: UDP-galactose mutase, and galactofuranosyl transferases GlfT1 and GlfT2. Moreover, we recapitulate the efforts aimed at their inhibition. The predicted common transition states of the three enzymes provide the lucrative possibility of multitargeting in pharmaceutical development, a favourable property in the mitigation of drug resistance. We believe that a tight interplay between target-based computational approaches and experimental methods will result in the development of original inhibitors that could serve as the basis of a new generation of drugs against tuberculosis.

Rapid Entry into Biologically Relevant α,α-Difluoroalkylphosphonates Bearing Allyl Protection-Deblocking under Ru(II)/(IV)-Catalysis

A convenient synthetic route to α,α-difluoroalkylphosphonates is described. Structurally diverse aldehydes are condensed with LiF2CP(O)(OCH2CH═CH2)2. The resultant alcohols are captured as the pentafluorophenyl thionocarbonates and efficiently deoxygenated with HSnBu3, BEt3, and O2, and then smoothly deblocked with CpRu(IV)(π-allyl)quinoline-2-carboxylate (1-2 mol %) in methanol as an allyl cation scavenger. These mild deprotection conditions provide access to free α,α-difluoroalkylphosphonates in nearly quantitative yield. This methodology is used to rapidly construct new bis-α,α-difluoroalkyl phosphonate inhibitors of PTPIB (protein phosphotyrosine phosphatase-1B).

Glycoside Mimics from Glycosylamines: Recent Progress

Glycosylamines are valuable sugar derivatives that have attracted much attention as synthetic intermediates en route to iminosugar-C-glycosyl compounds. Iminosugars are among the most important glycomimetics reported to date due to their powerful activities as inhibitors of a wide variety of glycosidases and glycosyltransferases, as well as for their use as pharmacological chaperones. As they provide ready access to these important glycoside mimics, we have reviewed the most significant glycosylamine-based methodologies developed to date, with a special emphasis on the literature reported after 2006. The groups of substrates covered include N-alkyl- and N-benzyl-glycosylamines, N-glycosylhydroxylamines, N-(alkoxycarbonyl)-, and N-tert-butanesulfinyl-glycosylamines.