63296-55-9Relevant articles and documents
THE STEREOSPECIFIC SYNTHESIS OF (S)-2-2H3>METHYL-2-METHYLBUTANOL. CHARACTERISATION OF THE (R) AND (S) ENANTIOMERS OF THE RACEMIC 2H3>ALCOHOL BY 2H-NMR IN THE PRESENCE OF A CHIRAL SHIFT REAGENT.
Harrison, David M.,Quinn, Philip
, p. 831 - 834 (1983)
The synthesis of the title compound is described.Assigment have been made in the 2H-NMR spectrum for the 2H3>methyl resonances of racemic 2-2H3>methyl-2-methylbutanol which were rendered anisochronous by the presence of tris(3-heptafluorobutyryl-d-camphorato)europium(III).
Iterative synthesis of deoxypropionate units: The inductor effect in acyclic conformation design
Hanessian, Stephen,Chahal, Navjot,Giroux, Simon
, p. 7403 - 7411 (2007/10/03)
Conjugate addition of lithium dimethylcuprate to acyclic α,β-unsaturated esters of varying lengths bearing terminal alkyl or phenyl groups leads to a preponderance of syn 1,3-adducts when one methyl is already present. Conversion to enoates, and iteration of cuprate additions also favors syn adducts to give contiguous deoxypropionate units in a growing chain. The effect of end-group variation (Me, i-Pr, phenyl, tert-butyl) in conjunction with the nature of the ester group (Me, tert-butyl, etc.) on the diastereoselectivity of syn and anti products was studied. The results are rationalized in terms of inductor effects related to the minimization of the 1,5-pentane interactions in energetically favored folded conformations and corroborated by homodecoupling NMR studies.
Acyclic stereoselection in the tertiary amine-catalysed addition of activated vinyl systems (Baylis-Hillman reaction) to protected chiral α-hydroxy and α-amino aldehydes
Manickum, Thavrin,Ross, Gregory H. P.
, p. 1 - 16 (2007/10/03)
The non chelation-controlled aldol-type addition of the ambident vinyl α anions derived from acrylic esters and methyl vinyl ketone to a series of protected chiral α-hydroxy and α-amino aldehydes has been investigated in order to assess some of the factors which contribute to the control of the diastereofacial selectivity.Whlist the α-methylene-β,γ-disubstituted carbonyl products showed a general preference for selectivity, some examples of syn predominance were made possible via a 'substituent tuning'approach.The observed diastereomer ratios have been interpreted in terms of the Felkin model and the Anh-Eisenstein proposals for 1,2-asymmetric induction.Simple steric effects appear to be as important as ?-orbital energies in the designation of the large 'anti group' for the application of these transition-state interpretations.Attempts to improve the overall induction via double diastereoselection approach, which combines the 1,5-induction of chiral acrylates with the 1,2-induction already present, were largely inconclusive.Methods for the routine NMR assignment of the relevant stereo-substructures have been assessed and the use of novel complementary technique is described.
Asymmetric α-Aminoacid Synthesis using Rearrangement of Allylic Trifluoroacetimidates: Synthesis of Thymine Polyoxin C
Chen, Anqi,,Savage, Ian,Thomas, Eric J.,Wilson, Peter D.
, p. 6769 - 6772 (2007/10/02)
Improved procedures are reported for the synthesis of chiral trifluoroacetimidates and are applied to complete a total synthesis of thymine polyoxin C.
Enantiotopic group differentiation and kinetic resolution: Asymmetric reduction of meso-1,3-dihalides
Michael Chong,Sokoll, Kenneth K.
, p. 879 - 882 (2007/10/02)
Asymmetric reduction of 1,3-dihalides derived from glycerol occurs with moderate levels of enantiotopic group differentiation. A concomitant kinetic resolution increases the enantiometric purity of the initial product.
COMPLETELY STEREOCONTROLLED SYNTHESIS OF THE RIGHT FRAGMENT OF SALINOMYCIN, A POLYETHER ANTIBIOTIC, BY MEANS OF THE CHELATION-CONTROLLED GRIGNARD REACTION
Oikawa, Yuji,Horita, Kiyoshi,Yonemitsu, Osamu
, p. 1541 - 1544 (2007/10/02)
In the course of our synthetic study of salinomycin (1), an ionophorous polyether antibiotic, the γ-lactone (2) corresponding to the the C-21-C-30 fragment (the right fragment of 1 was synthesized from D-mannitol and ethyl L-lactate as chiral starting mat
High Diastereoface Selection in an Ester Enolate Addition to α-Alkoxy Aldehydes: Stereoselective Synthesis of α-Methylene-β-hydroxy-γ-alkoxy Esters
Banfi, Luca,Bernardi, Anna,Colombo, Lino,Gennari, Cesare,Scolastico, Carlo
, p. 3784 - 3790 (2007/10/02)
The aldol-type condensation of β-(dimethylamino)propionates 3 and 4 with a series of α-alkoxy aldehydes proceeds with unprecedented high stereoselectivity (up to 24:1) to give anti α-methylene-β-hydroxy-γ-alkoxy esters.The best results were obtained when the reaction was carried out in diethyl ether and the ester enolate was allowed to equilibrate to the thermodynamically more stable geometric isomer.
Stereoselective Synthesis of α-Methylene-β-hydroxy-γ-alkoxy Esters from α-Alkoxy Aldehydes
Banfi, Luca,Colombo, Lino,Gennari, Cesare,Scolastico, Carlo
, p. 1112 - 1113 (2007/10/02)
The Reformatsky-type condensation between methyl and t-butyl 3-(N,N-dimethylamino)propionates (9) and (10) with α-alkoxy aldehydes, which has been studied on varying the protective group of the aldehyde, proceeds with good diastereoselectivity.
