2040-44-0Relevant academic research and scientific papers
Lewis-base-catalysed selective reductions of ynones with a mild hydride donor
Sch?mberg,Zi,Vilotijevic
supporting information, p. 3266 - 3269 (2018/04/05)
Ynones are efficiently reduced with a mild hydride donor in the presence of a catalytic amount of nucleophilic phosphines. The reactions are selective 1,2-reductions that give propargyl alcohols in yields of up to 96%. It is proposed that success in these reactions depends on the activation of ynones by a Lewis base catalyst. A protic additive plays a key role in suppressing the undesired reaction pathways and accelerating the 1,2-reductions.
Deacylative oxidation strategy for the preparation of α- functionalized carbonyls
Brodsky, Benjamin H.,Du Bois
, p. 2619 - 2621 (2007/10/03)
(Matrix Presented) α-Alkoxylation and amination of carbonyl derivatives is made possible through a unique deacylative coupling reaction that proceeds via in situ Rh-carbene formation and subsequent heteroatom-H (X-H) insertion. Reactions perform optimally
PROCESS FOR PREPARATION OF OPTICALLY ACTIVE PROPOXYANILINE DERIVATIVES
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Page 15, (2008/06/13)
Treatment of a lactic acid ester derivative with an enzyme or the like, which has asymmetric ester-hydrolyzing ability, can specifically hydrolyze the ester moiety of an isomer existing as the pair to the racemic derivative. Use of the compound obtained by this hydrolysis makes it possible to produce an optically active propoxyaniline derivative by a shorter process than the conventional art.
Hydroxynitrile lyase catalyzed enantioselective HCN addition to O-protected α-hydroxyaldehydes
Roos, Juergen,Effenberger, Franz
, p. 2817 - 2828 (2007/10/03)
Various O-protected glycol- and racemic lactaldehydes 3 and 6 as well as O-allyl protected racemic α-hydroxyaldehydes 7 (R1=Et, Pr, Bu) have been prepared to investigate and perform a stereoselective Kiliani-Fischer synthesis by hydroxynitrile lyase (HNL) catalyzed addition of HCN. From all protecting groups investigated the allyl moiety was most suitable. (R)-PaHNL from bitter almonds (Prunus amygdalus), yielding the (2S)-cyanohydrins 8-10, was found to be a more stereoselective catalyst than (S)-MeHNL from maniok (Manihot esculenta). While (R)-PaHNL led to enantiomeric excesses ≥93%, with (S)-MeHNL the (2R)-cyanohydrins 8-10 were obtained with enantiomeric excesses ≤78%.
Cesium promoted O-alkylation of alcohols for the efficient ether synthesis
Dueno,Chu,Kim,Kyung Woon Jung
, p. 1843 - 1846 (2007/10/03)
Efficient Williamson type O-alkylation of alcohols was developed using cesium bases in the presence of tetrabutylammonium iodide (TBAI) and molecular sieves. Various substrates including unreactive primary and secondary alcohols were converted smoothly to
Stereoselective Reactions of Phthalimido-Substituted Radicals Derived from (±)-Threonine: A Comparison with Reactions of N-Phthaloyliminium Ions
Stojanovic, Aleksandar,Renaud, Philippe,Schenk, Kurt
, p. 268 - 284 (2007/10/03)
Stereoselective reactions of phthalimido-substituted radicals derived from (±)-threonine with different radical traps are reported (Scheme 3, Table 1). A strong influence of the nature of the radical trap on the stereoselectivity was noticed. Small nucleophilic radical traps gave preferentially the syn products. The observed selectivities are explained with the A1.3 strain model and depend on steric and electronic effects (Fig. 2). Reactions with electrophilic radical traps such as diphenyl diselenide gave the anti diastereoisomers with moderate stereocontrol, presumably due to stereoelectronic effects. The same stereochemical outcome, i.e., preferential formation of the anti products, was observed for the reactions of the related N-phthaloyliminium ion (Scheme 5, Table 2). The stereochemistry of the ionic reaction is rationalized by a Felkin-Anh model (Fig. 3).
Stereoselective Radical Additions of γ-Oxy-α,β-unsaturated Ester Derivatives; 1,2-Asymmetric Induction in Acyclic and Cyclisation Systems
Morikawa, Tsutomu,Washio, Yoshiaki,Harada, Susumu,Hanai, Ryo,Kayashita, Takashi,et al.
, p. 271 - 282 (2007/10/02)
Examination was made of 1,2-asymmetric induction in the addition of alkyl radicals to γ-oxy-α,β-unsaturated ester derivatives 1 and 2 prepared from ethyl lactate and (R)-2,3-O-isopropylideneglyceraldehyde 3, respectively.The addition reactions of hexyl, cyclohexyl and 3-phenylpropyl radicals to (Z)-2 derived from aldehyde 3 gave β-addition products with syn-stereoselectivity (syn:anti = 8.6:1 - syn only).The reactions of (E)-2 were non-stereoselective.Based on allylic strain, a transition-state model for the syn-stereoselectivity is proposed. 1,2-Asymmetric induction was carried out in radical cyclisation to synthesize optically active cyclohexane derivatives.
MICROBIAL REDUCTION OF 2-PHENYLPROPIONIC ACID, 2-BENZYLOXYPROPIONIC ACID AND 2-(2-FURFURYL)PROPIONIC ACID
Tsuda, Yoshiko,Kawai, Ken-Ichi,Nakajima, Shoichi
, p. 4657 - 4661 (2007/10/02)
Racemic 2-phenylpropionic acid and 2-benzyloxypropionic acid were subjected to microbial reduction and simultaneous resolution with several molds. i. e., Malus and Prunus strains of Glomerella cingulata, Gloeosporium olivarum and Gloeosporium laeticolor, yielding (R)-2-phenylpropanol and (S)-2-benzyloxypropanol , and leaving (R)-2-phenylpropionic acid , respectively.The microbial reduction of racemic 2-(2-furfuryl)propionic acid gave optically inactive (+/-)-2-(2-furfuryl)propanol .Keywords- asymetric reduction; 2-benzyloxypropionic acid; 2-(2-furfuryl)prioionic acid; microbial reduction; microbial resolution; 2-phenylpropionic acid
