- The orthoester Johnson-Claisen rearrangement of allylic terpenols in the presence of acidic ionic liquid
-
A convenient protocol for the synthesis of natural isoprenoid-derived carboxylic esters via reaction of allylic terpenols with triethyl orthoacetate (propionate) in the presence of 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim][PF6] (10 mol%), has been developed. The desired terpene derivatives were prepared in moderate to high yield. The ionic liquid (IL) can be easily separated from the products and repeatedly used up to ten times without reduction in the product yield. Experimental data evidence that HF, generated in situ from the IL, most likely acts as a true catalyst in the Johnson-Claisen rearrangement.
- Kryshtal, Galina V.,Zhdankina, Galina M.,Ignat'ev, Nikolai V.,Schulte, Michael,Zlotin, Sergei G.
-
-
Read Online
- Titanocene(III)-catalyzed 6-exo versus 7-endo cyclizations of epoxypolyprenes: Efficient control and synthesis of versatile terpenic building blocks
-
In this article, a complete study on the selectivity of titanocene(III) cyclization of epoxypolyprenes is presented. The requirements for the formation of six- or seven-membered rings during these cyclizations are determined, taking into account the different substitution pattern in the epoxypolyprene precursor. Thus, a complete selectivity to 6-exo or 7-endo cyclization process has been achieved, yielding mono-, bi-, and even tricyclic compounds, constituting a new and efficient access to this type of derivative. Additionally, this procedure opens the possibility to prepare excellent building blocks for the synthesis of polycyclic compounds with a trisubstituted oxygenated function, which is present in several natural terpenes.
- Justicia, Jose,Jimenez, Tania,Miguel, Delia,Contreras-Montoya, Rafael,Chahboun, Rachid,Alvarez-Manzaneda, Enrique,Collado-Sanz, Daniel,Cardenas, Diego J.,Cuerva, Juan M.
-
-
Read Online
- Bis(phosphine)cobalt dialkyl complexes for directed catalytic alkene hydrogenation
-
Planar, low-spin cobalt(II) dialkyl complexes bearing bidentate phosphine ligands, (P - P)Co-(CH2SiMe3)2, are active for the hydrogenation of geminal and 1,2-disubstituted alkenes. Hydrogenation of more hindered internal and endocyclic trisubstituted alkenes was achieved through hydroxyl group activation, an approach that also enables directed hydrogenations to yield contrasteric isomers of cyclic alkanes.
- Friedfeld, Max R.,Margulieux, Grant W.,Schaefer, Brian A.,Chirik, Paul J.
-
supporting information
p. 13178 - 13181
(2015/03/30)
-
- ELECTROCHEMICAL OXIDATION OF ORGANOSILICON COMPOUNDS I. OXIDATIVE CLEAVAGE OF CARBON-SILICON BOND IN ALLYLSILANES AND BENZYLSILANES
-
Electrochemical oxidation of allylsilanes and benzylsilanes in the presence of alcohol, carboxylic acid, or water resulted in cleavage of the carbon-silicon bond and formation of the corresponding ether, ester, or alcohol, respectively.
- Yoshida, Jun-ichi,Murata, Toshiki,Isoe, Sachihiko
-
p. 3373 - 3376
(2007/10/02)
-
- PHOTOCHEMISTRY OF AZOLES, PART VII. PHOTOSOLVOLYSIS OF ALKYLMERCAPTOAZOLES. AN APPLICATION TO SOME ACYCLIC MONOTERPENE DERIVATIVES
-
Salts derived from 2-alkylmercapto-1-methylimidazoles 1b-e and 3-alkylmercapto-4-methyl-1,2,4-triazoles 2b-d have been found to undergo photochemical heterolytic fission of the S-alkyl bond in aqueous or methanolic solution to give solvolysis-type products.
- Iwasaki, Shigeo
-
p. 125 - 138
(2007/10/02)
-