770-62-7Relevant academic research and scientific papers
Novel synthetic approach to the 8,10-dimethyl anti-syn-anti-perhydrophenanthrene skeleton
Coltart, Don M.,Danishefsky, Samuel J.
, p. 1289 - 1292 (2007/10/03)
(Matrix presented) An efficient and highly stereocontrolled approach to the 8,10-dimethyl anti-syn-anti-perhydrophenanthrene carbon skeleton starting with the Wieland-Miescher ketone is described. The approach centers on a Diels-Alder-angular methylation-
BORON ANNULATION IN ORGANIC SYNTHESIS. 4. SILICON EFFECTS WITH TETRASUBSTITUTED OLEFINS
Akers, James A.,Bryson, Thomas A.
, p. 2187 - 2190 (2007/10/02)
Selectivity for hydroboration and boron decalone annulation employing tetrasubstituted olefins is strongly influenced by allylic silicon.
α-ALKYLATION AND α-ALKYLIDENATION OF CARBONYL COMPOUNDS BY O-SILYLATED ENOLATE PHENYLTHIOALKYLATION
Paterson, Ian
, p. 4207 - 4220 (2007/10/02)
For many reactions next to a carbonyl group, the use of O-silylated enolate chemistry offers improvements in yield and selectivity over the corresponding reactions of Group I metal enolates.In the case of α-alkylation of carbonyl compounds, Lewis acid (TiCl4 or ZnBr2) promoted phenylthioalkylation of O-silylated enolates 3 by α-chlorosulphides 4 (R3=H, Me, Prn, Pri, Bui, and Me3Si), followed by reductive sulphur removal by Raney nickel, 5->6, is found to be a reliable method for this synthetically important C-C bond forming step.An alternative sulphur elimination pathway via the sulphoxide, 5->7, allows the regio- and stereocontrolled α-alkylidenation of carbonyl compounds.The phenylthioalkylation reaction is applicable to ketones, aldehydes, esters, and lactones.
Proton Catalyzed Water Elimination from 1-Decalon and 8α-Methyl-1-Decalon in the Gas Phase. Loss of the Stereochemical Integrity of the cis/trans Ring Juncture for (+) Ions
Wolfschuetz, Roland,Halim, Hermann,Schwarz, Helmut
, p. 724 - 735 (2007/10/02)
Water loss from protonated gaseous 1-decalon and 8α-methyl-1-decalon under the condition of chemical ionisation mass spectrometry proceeds via at least three distinct pathways, all of which commences with a -hydrogen or -methyl migration, thus giving rise to the formation of the central intermediate 10.H2O loss from 10 proceeds either directly, involving a hydrogen from the position (C-4a) (Scheme 3; pathway 10 --> 15 --> 16), or from the rearranged ions 17 and/or 20.The fact that cis- and trans-8a-methyl-1-decalones and their deuterated isotopomers behave essentially identical is explained by loss of the stereochemical integrity of the ring conjunction.The mechanistic features of this unusual process (Scheme 2) have been explored by semi-empirical MINDO/3 calculations for the model system 23 (Scheme 4).The calculations reveal that there are two competing pathways for CH3 migration, one involving a sequence of -shifts (23 --> 24 --> 25 --> 26 --> 27), the other - being energetically less favoured - corresponds to a direct -methyl migration (Scheme 6; 23 --> 33 --> 27), in which the methyl group migrates with retention of configuration.This process is symmetry forbidden.For the corresponding symmetry allowed -methyl migration with inversion of configuration of the migrating group no pathway could be detected computationally.Both the experimental and theoretical investigations allow one to draw a detailed picture of H2O loss from protonated cyclic ketones in the gas phase. - The syntheses of the labelled substrates are described in detail. - Key words: Protonated Ketones, Wagner-Meerwein Rearrangement, Quantum Mechanical Calculations, Potential Energy Surface Calculations
STEREOCHIMIE - LIV. INFLUENCE DU DEGRE DE SUBSTITUTION DE LA DOUBLE LIAISON ETHYLENIQUE SUR LA STEREOCHIMIE DE L'HYDROCYANATION 1,4 DE CETONES CONJUGUEES
Agami, C.,Fadlallah, M.,Levisalles, J.
, p. 909 - 914 (2007/10/02)
The topological isomerism between octalinones in which the enone group has two distinct locations does not lead to any difference on the stereochemistry of the hydrocyanation of these substrates; the cyano group is axial in the kinetically controlled products.On the contrary, the stereoselectivity is strikingly reversed when the enone group is substituted by a methyl β to the carbonyl, leading to the introduction of the cyano group in an equatorial configuration in the kinetically controlled products.
