Towards conformationally-locked difluorosugar analogues: an unexpected sense of dihydroxylation.

Difluorinated cyclooctenones, synthesised using RCM, can be used as templates for stereoselective oxidative transformations to products that undergo transannular reactions to afford conformationally-locked analogues of 2-deoxy-2,2-difluorosugars with different stereochemical relationships between the C-2 and C-3 hydroxyl groups.

Catalytic asymmetric synthesis of a 1-deoxy-1,1-difluoro-D-xylulose.

[reaction: see text] A new route, of potential strategic importance, to a difluorosugar analogue has been developed. Key steps included a Stille coupling and a highly regio- and enantioselective dihydroxylation of a highly substituted diene. Protecting groups were chosen to enhance the reactivity of the disubstituted allylic fragment in the AD reaction and allow deprotection under orthogonal conditions.

Syntheses of selectively fluorinated cyclodecenones: the first deployment of the neutral oxy-Cope rearrangement in organofluorine chemistry.

Metallated haloalkenes were used to open epoxides in moderate to good yield. The homoallylic alcohols obtained underwent Swern oxidation to afford three gamma,gamma-difluorinated beta,gamma-enones, which reacted with either vinyllithium,2-lithio-2H-dihydropyran or another metallated haloalkene to afford substituted trans-1,2-divinylcyclohexanols of different degrees of stability. These intermediates underwent neutral thermal oxy-Cope rearrangements when heated in xylene in Ace tubes. The first-formed enols ketonised without loss of HF to afford a range of cyclodecenones in moderate to good yield; X-ray crystallography was used extensively for product characterisation. All substrates rearranged more rapidly than a cis/trans mixture of 1,2-divinylcyclohexanols.

Towards stable analogues of inositol phosphates: stereoselective syntheses of (alpha,alpha-difluoromethyl)phosphonic acid (DFMPA)-containing cyclohexanes.

Diels-Alder and conjugate addition reactions were used to prepare precursors to a range of fully functionalized and deoxy inositol phosphate analogues.

Rapid assembly of highly-functionalised difluorinated cyclooctenones via ring-closing metathesis.

Building block methodology from trifluoroethanol and ring-closing metathesis using a Fürstner modification of Grubbs' conditions allows the rapid synthesis of novel difluorinated cyclooctenones.