19549-70-3Relevant academic research and scientific papers
Carbonyl reduction with CaH2 and R3SiCl catalyzed by ZnCl2
Tsuhako, Akiko,He, Jing-Qian,Mihara, Mariko,Saino, Naoko,Okamoto, Sentaro
, p. 9120 - 9123 (2008/09/17)
Ketones and aldehydes were effectively reduced to the corresponding alcohols (or their silyl ethers) by the reaction with CaH2 and R3SiCl in the presence of a catalytic amount of ZnCl2. In the absence of the carbonyl substrate, the reagent reduced R3SiCl to the corresponding hydrosilane under mild reaction conditions.
Bioavailable diacylhydrazine ligands for modulating the expression of exogenous genes via an ecdysone receptor complex
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Page/Page column 52, (2008/06/13)
The present invention relates to non-steroidal ligands for use in nuclear receptor-based inducible gene expression system, and a method to modulate exogenous gene expression in which an ecdysone receptor complex comprising: a DNA binding domain; a ligand binding domain; a transactivation domain; and a ligand is contacted with a DNA construct comprising: the exogenous gene and a response element; wherein the exogenous gene is under the control of the response element and binding of the DNA binding domain to the response element in the presence of the ligand results in activation or suppression of the gene.
Sequestered alkyllithiums: Why phenyllithium alone is suitable for betaine-ylide generation
Wang, Qian,Deredas, Dariusz,Huynh, Cyril,Schlosser, Manfred
, p. 570 - 574 (2007/10/03)
The key step in the trans-selective modification of the Wittig reaction is the α-lithiation of the lithium bromide coordinated ylide - aldehyde adduct (the so-called "P-betaine"). Only phenyllithium effects this deprotonation rapidly and cleanly. Alkyllithiums (in particular, butyl-, sec-butyl-, and tert-butyllithium) react only sluggishly and incompletely, being tied up in very stable mixed aggregates with the lithium alkoxide part of the betaines.
Enantioselective butylation of aliphatic aldehydes by mixed chiral lithium amide/n-BuLi dimers
Arvidsson, Per I.,Davidsson, Oejvind,Hilmersson, Goeran
, p. 527 - 534 (2007/10/03)
The enantioselective butylation of aliphatic aldehydes with mixtures of n-butyllithium and chiral lithium amides in a diethyl ether-dimethoxymethane solvent mixture is described. Enantiomeric excesses ranging from 91 to 98.5% were observed for several aliphatic alcohols. The asymmetric butylation of the prochiral aldehydes proceeds much faster by the mixed lithium amide/n- BuLi complexes than by tetrameric n-BuLi.
Ti-TADDOLate-Catalyzed, Highly Enantioselective Addition of Alkyl- and Aryl-Titanium Derivatives to Aldehydes
Weber, Beat,Seebach, Dieter
, p. 7473 - 7484 (2007/10/02)
Toluene-ether or toluene-hexane solutions of aryl and alkyl triisopropoxy titanium reagents (free of Li, Mg, or Zn salts) are prepared from the corresponding Li or Grignard reagents and ClTi(OiPr)3, with careful removal of salts (centrifugation of LiCl or of dioxane*MgX2, and addition of 12-crown-4).The solutions of the organotitanium compounds are combined with one equiv. of an aldehyde and 0.2 equiv. of (R,R)-diisopropoxy-(α,α,α',α'-tetraphenyl-2,2-dimethyl-1,3-dioxolane-4,5-dimethanolato) titanium (Ti-TADDOLate 3) at dry-ice temperature.Warming up to room temperature leads to nucleophilic addition to the (Si)-face of the aldehydes with enantioselectivities as high as 99.5 : 0.5 (products 4-33 in Scheme 4).Functional groups or protecting groups and branching in the Ti-R group and in the aldehyde must be remote from the reacting centers.Aryl groups can be added to aldehydes by this method. - In contrast to all the enantioselective R2Zn additions to aldehydes, in which only one R-group is actually transferred, a twice as economic use is made of the originally employed R-metal reagent in the method described here. - A procedure for multigram preparation of the spiro-Ti-TADDOLate (2) employed for the in situ generation of catalyst (3) is described, and details of the determination of enantiomer ratios (er) by GC and NMR methods are given (Tab. 2, 3).The mechanistic interpretation of Ti-TADDOLate-mediated nucleophilic additions as derived previously (ref.4c) is also compatible with this monometallic variant of the method.
Synthesis of α-Hydroxy Ketones by Direct, Low-Temperature, in Situ Nucleophilic Acylation of Aldehydes and Ketones by Acyllithium Reagents
Seyferth, Dietmar,Weinstein, Robert M.,Hui, Richard C.,Wang, Wei-Liang,Archer, Colin M.
, p. 5620 - 5629 (2007/10/02)
The reaction of n-, sec-, and tert-butyllithium with CO at atmospheric pressure at -110 and -135 deg C in the appropriate solvent system in the presence of ketones and aldehydes generates the acyllithium, RC(O)Li, which reacts with the carbonyl compound to give the α-hydroxy ketone, generally in good yield.Reactions with aldehydes are limited in scope, working well with the t-BuLi-derived acyllithium reagents, but not with n-BuC(O)Li.
The evaluation of dicyclopentadienylsamarium as a reagent in organic synthesis
Namy,Collin,Zhang,Kagan
, p. 81 - 86 (2007/10/02)
SmCp2, which is easily prepared from SmI2, has been screened as a reducing agent for organic chemistry. In particular, SmCp2 promotes the pseudo-Barbier reaction between carbonyl compounds (aldehydes and ketones) and aliphatic or allylic halides more efficiently than does SmI2.
HIGH YIELD ACYL ANION TRANSFER REACTIONS: NUCLEOPHILIC ACYLATION OF ALDEHYDES
Seyferth, Dietmar,Weinstein, Robert M.,Wang, Wei-Liang,Hui, Richard C.
, p. 4907 - 4910 (2007/10/02)
Aldehydes be may acylated to give R'CH(OH)C(O)R in good yield by the RLi/CO in situ procedure at very low temperatures.Examples are given of ketone acylations which demonstrate the advantages of 1:1 RLi/substrate stoichiometry and the use of lower (-135 deg C) temperature.
Acyclic Stereoselection. 17. Simple Diastereoselection in the Addition of Medium- and Long-Chain n-Alkyl Ketone Lithium Enolates to Aldehydes
Heathcock, , Clayton H.,Lampe, John
, p. 4330 - 4337 (2007/10/02)
The n-alkyl tert-butyl ketones 1b-d have been prepared and the stereochemistry of their aldol reaction with benzaldehyde has been investigated.As with ketone 1a, ketones 1b-d give Z-enolates that react with benzaldehyde in THF at -78 deg C to give syn aldols.When the aldol additions are carried out in pentane, the syn aldols are also the kinetic products, but syn-anti equilibration is much more rapid in this solvent; after reaction at 25 deg C for 20 min, ketones 1c and 1d give only the anti aldols 3c and 3d.Aldolate syn-anti equilibration becomes more facile as the size of the α-alkyl group increases.Ketone 14 has been prepared and employed in a synthesis of methyl (+/-)-isocorynomycolate; the crucial aldol addition, leading to β-hydroxyketones 15 and 16, proceeds with kinetic stereoselection of only 4.5:1.
