Alison N. Hulme

The natural constituents of historical textile dyes

The sources and structures of dyes used to colour Western historical textiles are described in this tutorial review. Most blue and purple colours were derived from indigo--obtained either from woad or from the indigo plant--though some other sources (e.g. shellfish and lichens) were used. Reds were often anthraquinone derivatives obtained from plants or insects. Yellows were almost always flavonoid derivatives obtained from a variety of plant species. Most other colours were produced by over-dyeing--e.g. greens were obtained by over-dyeing a blue with a yellow dye. Direct analysis of dyes isolated from artefacts allows comparison with the historical record.

Total synthesis of the esterase inhibitor (±)-ebelactone a using an aldol-claisen strategy

Abstract The β-lactone (±)-ebelactone A has been prepared in 12 steps from diethylketone (9% overall yield) using a series of three boron enolate aldol reactions coupled with the Ireland ester enolate Claisen rearrangement, 10 → 11.

Studies towards the synthesis of the marine metabolite octalactin-A

Abstract Studies towards the synthesis of the marine metabolite octalactin A 1, are described. Key steps in this strategy include an anti aldol reaction to set the C 7 C 8 stereochemistry, Horner Wadsworth Emmons coupling to give the trisubstituted E -double bond and a novel samarium-mediated cyclisation reaction.

Self‐Assembly of Disorazole C1 through a One‐Pot Alkyne Metathesis Homodimerization Strategy

Alkyne metathesis is increasingly explored as a reliable method to close macrocyclic rings, but there are no prior examples of an alkyne-metathesis-based homodimerization approach to natural products. In this approach to the cytotoxic C2-symmetric marine-derived bis(lactone) disorazole C1, a highly convergent, modular strategy is employed featuring cyclization through an ambitious one-pot alkyne cross-metathesis/ring-closing metathesis self-assembly process.

Enabling methodology for the end functionalisation of glycosaminoglycan oligosaccharides

The chemical functionalization of glycosaminoglycans is very challenging due to their structural heterogeneity and polyanionic character; but as an enabling technology it promises rich rewards in terms of the structural and biological data it will afford. This review surveys the known methods for the preparation of glycosaminoglycan oligosaccharides and conditions for the selective functionalization of both the reducing and non-reducing ends. The synthetic merits of each approach are discussed, together with the structural modification of the glycosaminoglycan oligosaccharide which they confer. Recent applications of this methodology are highlighted, including introduction of functional labels for gel mobility shift assays and NMR studies of glycosaminoglycan-protein complexes, and synthesis of immobilised glycosaminoglycan arrays.

Flexible, phase-transfer catalyzed approaches to 4-substituted prolines.

A range of 4-substituted prolines can be rapidly synthesized from a protected glycine Schiff base in only four steps and in 27-55% overall yield. Phase transfer catalysis allows direct access to both enantiomeric series, and the relative stereochemistry at the 4-position is readily controlled (>10:1 dr) through the choice of hydrogenation conditions.

Stereocontrolled, two-directional, chain synthesis using the Boron Aldol reaction and double Ireland-Claisen rearrangement.

Abstract Long-chain, (4 E ,9 E )-unsaturated, diesters can be prepared efficiently by double Ireland-Claisen rearrangements, as in 4 → 5 → 6 . By combination with appropriate E ot Z enol borinate aldol reactions, a high level of stereocontrol can be achieved at the four chiral centres and two trisubstituted double bonds in 11, 15, 30, 31 and 32 .

Anti and Syn Glycolate Aldol Reactions with a Readily Displaced Thiol Auxiliary

The TBDPS protected glycolate derivative of thiol auxiliary 1 is readily prepared (3 steps, 80% overall yield) and has been shown to give excellent anti:syn selectivity (>97:3) and high facial selectivity (88:12 to 97:3) in glycolate aldol reactions with a range of aldehydes (75-87% isolated yield major diastereomer). In contrast, its benzyl protected counterpart displays more versatility with respect to the generation of either anti or syn glycolate aldol adducts, but only modest facial selectivity. The thiol auxiliary has been shown to be readily displaced under mild conditions to give alcohol and ester derivatives of the glycolate aldol adducts.

Triazole biotin: a tight-binding biotinidase-resistant conjugate

The natural amide bond found in all biotinylated proteins has been replaced with a triazole through CuAAC reaction of an alkynyl biotin derivative. The resultant triazole-linked adducts are shown to be highly resistant to the ubiquitous hydrolytic enzyme biotinidase and to bind avidin with dissociation constants in the low pM range. Application of this strategy to the production of a series of biotinidase-resistant biotin-Gd-DOTA contrast agents is demonstrated.

Historical textile dyeing with Genista tinctoria L.: a comprehensive study by UPLC-MS/MS analysis

Polyphenolic components from Genista species have been well characterised because of their potential as antioxidants and as therapeutic leads; however, the identification of dyers greenweed (Genista tinctoria L.) in historical textiles has been the subject of only limited studies. This paper presents a comprehensive UPLC-PDA MS/MS study of reference and historical yarns dyed with this species. Several so far unreported dye components that could assist with the identification of this dye source, were characterised by MS/MS. Furthermore, the effect of photo-degradation and textile preparation techniques (such as over-dyeing) on the dye fingerprint was investigated and the results correlated with those obtained from historical samples from the Burrell and Bodleian collections, UK.