81002-19-9Relevant academic research and scientific papers
Double asymmetric induction as a mechanistic probe: The doubly diastereoselective conjugate addition of enantiopure lithium amides to enantiopure α,β-unsaturated esters and enantiopure α,β-unsaturated hydroxamates
Davies, Stephen G.,Lee, James A.,Roberts, Paul M.,Thomson, James E.,Yin, Jingda
, p. 6382 - 6403 (2011/09/19)
The doubly diastereoselective conjugate addition of the antipodes of lithium N-benzyl-N-(α-methylbenzyl)amide to a range of enantiopure α,β-unsaturated esters [derived from Corey's 8-phenylmenthol chiral auxiliary] and enantiopure α,β-unsaturated hydroxamates [derived from our 'chiral Weinreb amide' auxiliary (S)-N-1-(1′-naphthyl)ethyl-O-tert- butylhydroxylamine] has been used as a mechanistic probe to determine the reactive conformations of these acceptors.
Diamination of Olefins: Synthesis, Structures and Reactivity of Osmaimidazolidines
Muniz, Kilian,Iesato, Atsushi,Nieger, Martin
, p. 5581 - 5596 (2007/10/03)
The diamination of certain olefins bearing electron-withdrawing substituents proceeds with well-defined bisimido and trisimido complexes of osmium. The products are obtained as osmaimidazolidines which are of unprecedented stability with regards to olefin functionalisation. Osmium complexes from related dihydroxylation or amino-hydroxylation are significantly less stable and thereby promote catalytic reactions. This difference in reaction profile has been investigated and chiral osmium heterocycles obtained from olefin difunctionalisation were characterised by X-ray analysis for the first time. Kinetic studies on the reaction profile have also been carried out. An asymmetric version of this reaction is based on chiral non-racemic auxiliaries and leads to diastereomerically enriched osmaimidazolidines with up to 90% de. This sequence represents the first asymmetric diamination of olefins. Attempts on the use of chiral ligands for direct asymmetric diamination as well as the consequences of osmaimidazolidine properties for a catalytic reaction are discussed.
THE RACEMIC FORM AND THE TWO ENANTIOMERS OF 4-METHYL-1-NONANOL, A SEX ATTRACTANT OF THE YELLOW MEALWORM, Tenebrio molitor L.
Carpita, Adriano,Magistris, Elisabetta De,Rossi, Renzo
, p. 99 - 106 (2007/10/02)
The racemic form of 4-methyl-1-nonanol, (R)(S)-1, a sex attractant secreted by the female of the yellow mealworm, has been synthesized in 31 percent overall yield from commercially available methyl 2-octynoate, 2.Almost enantiomerically pure (R)- and (S)-1 have been stereospecifically synthesized in 21.3 and 23.9 percent overall yields, respectively, starting from methyl hydrogen (R)-3-methylglutarate, (R)-3.A precursor for (S)-1, i.e. (S)-3-methyloctanoic acid, (S)-4, has been also prepared in 84 percent yield and over 96 percent enantiomeric purity by the BF3-mediated 1,4-addition of n-pentylcopper to (-)-8-phenylmenthyl crotonate, 15, followed by saponification.The enantiomeric purities of methyl (R)-3-methyloctanoate, (R)-7, and (S)-3-methyl-1-octanol, (S)-8, have been determined by converting these compounds into (R)- and (S)-3-methyloctanoic acid, (R)-4 and (S)-4, respectively, followed by GLC analysis of the corresponding 1-(1-naphthyl)ethylamides obtained from nearly optically pure (R)-1-(1-naphthyl)ethylamine.
High Asymmetric Induction in Conjugate Additions of RCu*BF3 to Chiral Enoates
Opplzer, Wolfgang,Loeher, Heinz J.
, p. 2808 - 2811 (2007/10/02)
1,4-Additions of PhCu*BF3, n-BuCu*BF3 and MeCu*BF3 to the trans-8-phenylmenthyl enoates 1 proceeded with high chiral induction.Saponification of the resulting esters 2 gave the corresponding enantiomerically pure β-substituted alkanoic acids 3 and the recovered (-)-8-phenylmenthol in good overall yields.Analogous additions to the cis-crotonate 1 led preferentially to the acids 3 enantiomeric to those obtained from the trans-crotonate 1, although with lower selectivity.A stereochemical model is proposed consistent with the observed results (Scheme 2, Table).
