79623-03-3Relevant academic research and scientific papers
Photoinduced molecular transformations. 157. A new stereo- and regioselective synthesis of 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane lignans involving a β-scission of alkoxyl radicals as the key step. New total syntheses of (±)-sesamin, (±)-eudesmin, and (±)-yangambin
Suginome,Orito,Yorita,Ishikawa,Shimoyama,Sasaki
, p. 3052 - 3064 (2007/10/02)
New total syntheses of naturally occurring 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane lignans, (±)-sesamin and (±)-eudesmin, and the first total synthesis of (±)-yangambin were achieved according to a general method devised by Suginome and colleagues for replacing the carbonyl group of the cyclopentanone ring with an oxygen atom to give a corresponding tetrahydrofuran ring involving a regioselective β-scission of alkoxyl radicals; arylation of dimethyl, diallyl, or dibenzyl 3,7-dioxobicyclo[3.3.0]octane-2,6-dicarbonate (18 and 19a,b) with aryllead triacetate 9a-c, followed by dealkoxycarbonylation of the resulting arylated product 20a-f, gave 2,6-diaryl-3,7-dioxobicyclo[3.3.0]octane 21a-c. A regioselective Baeyer-Villiger oxidation of 21a-c with m-CPBA-NaHCO3 or -K2CO3 gave the corresponding δ-lactone 22a-c, which was reduced with DIBAL to give the corresponding lactol 23a-c. The irradiation of a solution of the hypoiodite of 23a-c, generated in situ with mercury(II) oxide-iodine, in benzene with Pyrex-filtered light resulted in a regioselective β-scission of the corresponding alkoxyl radical to give iodo formate 24a-c. Heating 24a-c in MeOH with NaBH4 gave (±)-sesamin (25a), (±)-eudesmin (25b), or (±)-yangambin (25c).
Thallium in Organic Synthesis. 61. Intramolecular Capture of Radical Cations from Thallium(III) Trifluoroacetate Oxidation of Arylalkanoic Acids and Arylalkanols. New Routes to Oxygen Heterocycles
Taylor, Edward C.,Andrade, Juan G.,Rall, Gerhardus J. H.,Turchi, Ignatius J.,Steliou, Kosta,et al.
, p. 6856 - 6863 (2007/10/02)
Treatment of electron-rich arylpropionic acids with TTFA in TFA containing a small amount of BF3*etherate results in the formation of dihydrocoumarins and spirocyclohexadienone lactons by initial formation of aromatic radical cations followed by intramolecular cyclization involving the side-chain carboxyl group.The scope and limitations of this reaction with respect to aromatic substitution and the length of the alkanoic acid side chain have been examined; the reaction has been extended with analogous results to 1-naphthalenylalkanoic acids.Oxidation of a series of homologous phenyl- and naphthalenyl-1-alknols with TTFA under similar conditions results in intramolecular cyclization to give fused or pendant cyclic esters.It is suggested that the observed propensity for intramolecular cyclization may due to complexation of both the aryl group and the side-chain basic substituent (-COOH or -OH) with thallium(III).
