Agonists of the γ-aminobutyric acid type B (GABA) receptor derived from β-hydroxy and β-amino difluoromethyl ketones.

β-Hydroxy difluoromethyl ketones represent the newest class of agonists of the GABA-B receptor, and they are structurally distinct from all other known agonists at this receptor because they do not display the carboxylic acid or amino group of γ-aminobutyric acid (GABA). In this report, the design, synthesis, and biological evaluation of additional analogues of β-hydroxy difluoromethyl ketones characterized the critical nature of the substituted aromatic group on the lead compound. The importance of these new data is interpreted by docking studies using the X-ray structure of the GABA-B receptor.

Conversion of Methyl Ketones and Methyl Sulfones into α-Deutero-α,α-Difluoromethyl Ketones and α-Deutero-α,α-Difluoromethyl Sulfones in Three Synthetic Steps.

Deuterodifluoromethyl ketones and sulfones were assembled in three synthetic steps from methyl ketones and sulfones, respectively. The key synthetic transformation is the deuteration of the difluorocarbanion generated by the release of trifluoroacetate from highly α-fluorinated gem-diols. High levels of deuterium on the "CFD" group were routinely observed.

Optimized Synthesis of a Pentafluoro--diol and Conversion to a -Glucopyranose through Trifluoroacetate-Release and Halogenation.

Pentafluoro--diols are substrates that enable the synthesis of valuable difluoromethylene-containing organic molecules through the release of trifluoroacetate. Currently, only one synthetic strategy is available to assemble these important precursors. Herein, two new synthetic strategies to a complex pentafluoro--diol are compared to the existing route, and an improved synthetic route has completed.

Synthesis of α-halo-α,α-difluoromethyl ketones by a trifluoroacetate release/halogenation protocol.

Three series of α-halo-α,α-difluoromethyl ketones are prepared from highly α-fluorinated gem-diols by exploiting the facile release of trifluoroacetate, followed by immediate trapping of the liberated α,α-difluoroenolate with an electrophilic chlorine, bromine, or iodine source. The products are typically isolated in good yields, even in the case of sensitive, α-iodo-α,α-difluoromethyl ketones. Also, we demonstrate that an α-iodo-α,α-difluoromethyl ketone will participate in a copper-promoted reaction to forge a new carbon-carbon bond.

Exploiting the facile release of trifluoroacetate for the α-methylenation of the sterically hindered carbonyl groups on (+)-sclareolide and (-)-eburnamonine.

An efficient method for the α-methylenation of carbonyl groups is reported, and this transformation is accomplished by a facile elimination of trifluoroacetate during the formation of the olefin. This method represents an improvement beyond existing protocol in cases of steric hindrance, and we have demonstrated the utility of the process across a series of ketones, lactams, and lactones. Additionally, we have applied this method to produce semisynthetic derivatives of the natural products (+)-sclareolide and (-)-eburnamonine, in which the carbonyl group is proximal to bulky functional groups.

Formation of six- vs. five-membered cyclic sulfones by C-H insertion.

Selectivity of six- vs. five- membered ring formation in C-H insertion on alkylsulfonyl diazoacetates is sensitive to the substrate structure and catalyst used.

Synthesis of plakortethers F and G.

Synthesis of plakortethers F and G has been performed by taking advantage of the symmetry in the structure. The structures of the prepared compounds have been confirmed by COSY, 1D NOE, and chemical transformation studies. The synthetic plakortether F was found to match the natural product by all physical data.

Selective formation of six-membered cyclic sulfones and sulfonates by C-H insertion.

[reaction: see text] Carbethoxy diazosulfones and sulfonates, easily available from corresponding sulfones and sulfonates, undergo C-H insertion with preferential formation of six membered cyclic sulfones and sulfonates.