57804-27-0Relevant articles and documents
Synthesis of allylsilanes by reductive lithiation of thioethers
Streiff, Stephane,Ribeiro, Nigel,Desaubry, Laurent
, p. 7592 - 7598 (2007/10/03)
Although much work in reductive lithiation has been done, the utilization of allylthioethers bearing various substituents to prepare allylsilanes has not been explored. The main reason clearly stems from the anticipated lack of regioselectivity. We describe herein the first study on the regioselectivity of the reductive silylation involving dissymmetric allylthioethers. We surveyed a broad spectrum of parameters and showed that this process displays a great dependence of the reaction conditions. We also discovered that an electron transporter, DBB or naphthalene, can cleave THF at room temperature by sonication, to generate a strong base, 4-lithiobutoxide. This feature was successfully exploited to the straightforward synthesis of bis-silanes in one pot. Examples are provided for maximizing both the chemical yield and the regioselectivity of the reductive silylation through the tuning of the reaction conditions. By changing these conditions, several allylsilanes can be selectively synthesized from one thioether.
Synthesis and NMR characterisation of novel highly cyclised polyprenoid hydrocarbons from sediments
Grosjean,Poinsot,Charrie-Duhaut,Tabuteau,Adam,Trendel,Schaeffer,Connan,Dessort,Albrecht
, p. 711 - 719 (2007/10/03)
We report here on the identification of two novel hexacyclic alkanes (C33 and C35) occurring in bitumen. The C35 compound 1 was identified by comparison with a standard obtained by synthesis involving a biomimetic proton-induced extensive cyclisation of an acyclic heptaprenoid. This cascade cyclisation allows the formation of eleven asymmetric centres present in the natural compound in only one step. The C33 analogue 2 was identified by NMR studies after isolation from the saturated hydrocarbon fraction of a bituminous rock. Both compounds are "orphan" molecular fossils of biological lipids of unknown origin formed by the extensive cyclisation of higher regular polyprenoids.
Novel regio- and stereoselective cascade 6-endo-trig cyclisations from polyene acyl radical intermediates leading to steroid-like pentacycles and heptacycles
Handa, Sandeep,Nair, Prathap S.,Pattenden, Gerald
, p. 2629 - 2643 (2007/10/03)
In a quite remarkable regio- and stereoselective manner, each of the (all-E)-polyene selenoates 5a-c is shown to undergo cascade radical-mediated polycyclisations via consecutive 6-endo-trig reactions, leading to the corresponding all-trans, anti, tri-, penta- and heptacycles, i.e., 20, 23, and 25, in good yields. The configurations of these 'steroid-like' polycycles followed from detailed examination and correlation of chemical shift data in their 13C-NMR spectra.
Novel cascade of seven radical-mediated 6-endo-trig cyclisations leading to a unique all-trans, anti heptacycle
Handa, Sandeep,Pattenden, Gerald
, p. 843 - 845 (2007/10/03)
A cascade of seven radical-mediated 6-endo-trig cyclisations from the all-E-heptaene selenoate ester 1 results in the production of the all-trans, anti heptacycle 2 together with the isolation of the all-trans, anti tetracycle 15.
Tetra-n-butylammonium Oxone. Oxidations under Anhydrous Conditions
Trost, Barry M.,Braslau, Rebecca
, p. 532 - 537 (2007/10/02)
Tetra-n-butylammonium Oxone, readily prepared as a white solid from commercially available Oxone, performs oxidations in anhydrous methylene chloride.Under these conditions, sulfides are oxidized to sulfones in the presence of amines, ketones, esters, car
NOVEL APPROACH TO THE STEREOSELECTIVE SYNTHESIS OF POLYPRENOLS VIA DIRECTED ALDOL CONDENSATION. PREPARATION OF HEPTAPRENOLS ωtttcccOH AND ωtttcctOH.
Grigorieva, N. Ya.,Avrutov, I. M.,Semenovsky, A. V.
, p. 5531 - 5534 (2007/10/02)
New convenient and stereoselective route to linear isoprenoids including the construction of Z-trisubstituted double bond is elaborated based on directed aldol condensation.
