We report an efficient Mukaiyama-aldol reaction of tryptanthrin with fluorinated enol silyl ethers, which is carried out in methanol without the use of any catalyst. This method is applied to the total synthesis of the difluoro analogues of the natural product Phaitanthrin B.

Pulse Radiolysis, OH Radicals, Acetylacetone, Reaction Mechanisms Pulse radiolysis experiments monitoring optical absorbance as well as conductivity and in-situ ESR radiolysis studies show that the OH radical reacts with the enol (k = 8.6 x 109 M_1 s_1) and the enolate (k = 7.4 X 109 M_1 s-1) forms of acetylacetone by addition to the C = C double bond in aqueous N2O saturated solution. The OH r...

In spite of the enormous importance, reactions of cationic electrophiles with silylated enol ethers have adopted in organic synthesis,* kinetic data on such reactions are rare.u Previously we have reported rate constants for the reactions of alkenes, allylelement compounds, and enol ethers toward chloro-, methyl-, and alkoxy-substituted benxhydryl cation& Because of the high nucleophilicity of ...

A stereodivergent synthesis of enantiopure 3,6-dihydro-2H-pyrans is presented. The addition of lithiated enol ethers to carbohydrate-derived nitrones afforded syn- or anti-configured hydroxylamine derivatives 4a-d that were cyclized under Lewis acidic conditions to yield functionalized dihydropyrans cis- or trans-5a-d containing an enol ether moiety. This functional group was employed for a var...

A diastereoselective synthesis of cis-2,6-disubstituted tetrahydropyran-4-ones was developed. The key step of this methodology, a silyl enol ether Prins cyclization, was promoted by a condensation reaction between a hydroxy silyl enol ether and an aldehyde to afford substituted tetrahydropyran-4-ones. The cyclization was tolerant of many functional groups, and the modular synthesis of the hydro...

Stereodefined enol derivatives of aldehydes are prepared from terminal alkynes. Specifically, terminal alkynes are known to undergo Cp2ZrCl2-catalyzed methylalumination. Here, we show that the resultant vinylalanes can be oxygenated with peroxyzinc species to generate trisubstituted enolates. Electrophilic trapping with carboxylic anydrides or silyl triflates yields trisubstituted enol esters o...

We report the highly efficient gold-catalyzed hydrocarboxylation of internal alkynes that operates under solvent- and silver-free conditions. This new, simple, and eco-friendly protocol allows for the synthesis of a wide variety of functionalized aryl and alkyl enol esters in high yields, with Z-stereospecificity and good regioselectivities and without the requirement for purification by chroma...

The title Schiff base compound, 0.57C(17)H(12)FNO·0.43C(17)H(12)FNO, reveals both the enol (OH) and keto (NH) tautomeric forms with occupancies of 0.57 (6) and 0.43 (6), respectively. The tautomeric forms are stabilized by intra-molecular O-H⋯N (enol) and N-H⋯O (keto) hydrogen bonds. The dihedral angle between the naphthalene ring system and the benzene ring is 32.76 (1)°.

A variety of functionalized 3,4-benzo-7-hydroxy-2,9-diazabicyclo[3.3.1]non-7-enes were prepared by one-pot cyclizations of 1,3-bis(silyl enol ethers) with quinazolines. The mechanism of the cyclization was studied by B3LYP/6-31G(d) density functional theory computations. The products could be functionalized by Suzuki cross-coupling reactions. The reaction of 1,3-bis(silyl enol ethers) with phth...

The use of enol phosphinates as electrophiles for cross-coupling reactions has been explored. Both boronic acids (Suzuki-Miyaura reaction) and stannanes (Stille reaction) couple efficiently with lactam derived phosphinates.