- Reductive Ring-Opening 1,3-Difunctionalizations of Arylcyclopropanes with Sodium Metal
-
Sodium dispersion promotes reductive ring opening of arylcyclopropanes. The presence of a reduction-resistant electrophile, such as methoxypinacolatoborane, epoxide, oxetane, paraformaldehyde, or chlorotrimethylsilane, during the reductive ring opening event leads to the formation of 1,3-difunctionalized 1-arylalkanes by immediate trappings of the resulting two reactive carbanions. In particular, the ring-opening 1,3-diborylations of arylcyclopropanes afford 1,3-diborylalkanes with high syn selectivity.
- Wang, Shuo,Kaga, Atsushi,Yorimitsu, Hideki
-
p. 219 - 223
(2020/11/04)
-
- Cascade Reaction by Chemo- and Biocatalytic Approaches to Obtain Chiral Hydroxy Ketones and anti 1,3-Diols
-
A chemo- and biocatalytic cascade approach was applied for the stereoselective synthesis of hydroxy ketones and the corresponding 1,3-diols. A new class of tridentate N,N,O ligands was used with copper(II) complexes for the asymmetric β-borylation of α,β-unsaturated compounds. The complex containing ligand L5 emerged as the best performer, and it gave the organoborane derivatives with good ee values. The corresponding keto–alcohol compounds were then bioreduced by yeasts. The biotransformation set up with Rhodotorula rubra allowed (R)-keto–alcohols and (S,S)-diols to be obtained with up to 99 % ee and up to 99 % de in favor of the anti enantiomers.
- Gandolfi, Raffaella,Facchetti, Giorgio,Christodoulou, Michael S.,Fusè, Marco,Meneghetti, Fiorella,Rimoldi, Isabella
-
p. 393 - 400
(2018/06/04)
-
- Lewis Base-Promoted Ring-Opening 1,3-Dioxygenation of Unactivated Cyclopropanes Using a Hypervalent Iodine Reagent
-
A facile and effective system has been developed for the regio- and chemoselective ring-opening/electrophilic functionalization of cyclopropanes through C?C bond activation by [bis(trifluoroacetoxy)iodo]benzene with the aid of the Lewis basic promoter p-toluenesulfonamide. The p-toluenesulfonamide-promoted system works well for a wide range of cyclopropanes, resulting in the formation of 1,3-diol products in good yields and regioselectivity.
- Gieuw, Matthew H.,Ke, Zhihai,Yeung, Ying-Yeung
-
supporting information
p. 3782 - 3786
(2018/03/13)
-
- Double Catalytic Kinetic Resolution (DoCKR) of Acyclic anti-1,3-Diols: The Additive Horeau Amplification
-
The concept of a synergistic double catalytic kinetic resolution (DoCKR) as described in this article was successfully applied to racemic acyclic anti-1,3-diols, a common motif in natural products. This process takes advantage of an additive Horeau amplif
- Merad, Jérémy,Borkar, Prashant,Caijo, Frédéric,Pons, Jean-Marc,Parrain, Jean-Luc,Chuzel, Olivier,Bressy, Cyril
-
p. 16052 - 16056
(2017/11/21)
-
- Asymmetric chemoenzymatic synthesis of 1,3-diols and 2,4-disubstituted aryloxetanes by using whole cell biocatalysts
-
Regio- and stereo-selective reduction of substituted 1,3-aryldiketones, investigated in the presence of different whole cell microorganisms, was found to afford β-hydroxyketones or 1,3-diols in very good yields (up to 95%) and enantiomeric excesses (up to 96%). The enantiomerically enriched aldols, obtained with the opposite stereo-preference by baker's yeast and Lactobacillus reuteri DSM 20016 bioreduction, could then be diastereoselectively transformed into optically active syn- or anti-1,3-diols by a careful choice of the chemical reducing agent (diastereomeric ratio up to 98 : 2). The latter, in turn, were stereospecifically cyclized into the corresponding oxetanes in 43-98% yields and in up to 94% ee, thereby giving a diverse selection of stereo-defined 2,4-disubstituted aryloxetanes.
- Vitale, Paola,Perna, Filippo Maria,Agrimi, Gennaro,Scilimati, Antonio,Salomone, Antonio,Cardellicchio, Cosimo,Capriati, Vito
-
p. 11438 - 11445
(2016/12/16)
-
- Highly enantioselective acylation of acyclic meso 1,3-diols through synergistic isothiourea-catalyzed desymmetrization/chiroablative kinetic resolution
-
A general and highly efficient organocatalyzed desymmetrization of acyclic meso 1,3-diols through acyl transfer using chiral isothioureas is described. The introduction of π-systems in the acyclic substrates provided new opportunities in terms of reactivi
- Merad, Jérémy,Borkar, Prashant,Bouyon Yenda, Tracy,Roux, Christèle,Pons, Jean-Marc,Parrain, Jean-Luc,Chuzel, Olivier,Bressy, Cyril
-
p. 2118 - 2121
(2015/05/13)
-
- Ansa-Ruthenium(II) Complexes of R2NSO2DPEN-(CH2)n(η6-Aryl) Conjugate Ligands for Asymmetric Transfer Hydrogenation of Aryl Ketones
-
New 3rd generation designer ansa-ruthenium(II) complexes featuring N,C-alkylene-tethered N,N-dialkylsulfamoyl-DPEN/η6-arene ligands, exhibited good catalytic performance in the asymmetric transfer hydrogenation (ATH) of various classes of (het)aryl ketones in formic acid/triethylamine mixture. In particular, benzo-fused cyclic ketones furnished 98 to >99.9% ee using a low catalyst loading.
- Ki?ic, Andrea,Stephan, Michel,Mohar, Barbara
-
supporting information
p. 2540 - 2546
(2015/08/18)
-
- Aerobic oxidative desymmetrization of meso-diols with bifunctional amidoiridium catalysts bearing chiral N-sulfonyldiamine ligands
-
Asymmetric aerobic oxidation of a range of meso- and prochiral diols with chiral bifunctional Ir catalysts is described. A high level of chiral discrimination ability of Cpa? -Ir complexes derived from (S,S)-1,2-diphenylethylenediamine was successfully demonstrated by desymmetrization of secondary benzylic diols such as cis-indan-1,3-diol and cis-1,4-diphenylbutane-1,4-diol, providing the corresponding (R)-hydroxyl ketones with excellent chemo- and enantioselectivities. Enantiotopic group discrimination in oxidation of symmetrical primary 1,4- and 1,5-diols gave rise to chiral lactones with moderate ees under similar aerobic conditions.
- Moritani, Junki,Hasegawa, Yasuharu,Kayaki, Yoshihito,Ikariya, Takao
-
p. 1188 - 1191
(2014/02/14)
-
- Asymmetric synthesis of new chiral 1,2- and 1,3-diols
-
Seven chiral 1,2-diols and six chiral 1,3-diols were synthesized by the asymmetric reduction of the corresponding 1,2-diketones and 1,3-diketones using oxazaborolidine-BH3 catalyst. The 13 corresponding racemic 1,2- and 1,3-diols were synthesized by reducing the diketones with NaBH4 and they were used for determining the ee values through their chiral resolution on HPLC and GC. Five starting diketones, four racemic 1,2-diols, five chiral 1,2-diols, and two chiral 1,3-diols are novel compounds. The new chiral compounds were characterized by IR, 1H and 13C NMR, MS, and elemental analysis. The asymmetric reduction method, oxazaborolidine-BH 3, was applied to these diketones for the first time in this study. The relationship between the structure of the diketone and the yield, diastereoselectivity, and enantiomeric excess was discussed.
- Yildiz, Tülay,Yusufo?lu, Ay?e
-
p. 183 - 190
(2013/07/27)
-
- Selective hydroformylation of various olefins using diphosphinite ligands
-
Novel diphosphinite ligands are synthesized by the reaction of various derivatives of 1,3-diols with chlorodiphenylphosphine. The synthesized ligands exhibited considerable impact on hydroformylation of various olefins with excellent regioselectivity toward branched aldehyde. The effect of solvent, temperature, pressure and catalyst loading on the hydroformylation reaction is also described. The synthesized diphosphinite ligands with rhodium precursor works under milder reaction conditions as compared to traditional phosphine and phosphite-based ligands. Copyright 2013 John Wiley & Sons, Ltd. A novel diphosphinite ligands are synthesized by the reaction of various derivatives of 1,3-diol with chlorodiphenylphosphine. The synthesized ligands exhibited a considerable impact on hydroformylation of various olefins with excellent regioselectivity toward branched aldehyde. The effect of solvent, temperature, pressure and catalyst loading on the hydroformylation reaction is also described. The synthesized diphosphinite ligands with Rhodium precursor works at milder reaction conditions as compared to traditional phosphine and phosphite based ligands. Copyright
- Khan, Shoeb R.,Bhanage, Bhalchandra M.
-
p. 313 - 317
(2013/07/04)
-
- Rearrangement of cyclopropylborane into boretane
-
Previously unknown boron-containing four-membered unsaturated heterocycle boretane was obtained via novel thermal rearrangement of cyclopropylborane and investigated by NMR and IR spectroscopy. Formation of boretane was also confirmed through its chemical
- Rubina, M.,Rubin, M.
-
p. 807 - 821,15
(2020/09/09)
-
- Albumin-directed stereoselective reduction of 1,3-diketones and β-hydroxyketones to anti diols
-
The reduction of 1,3-diketones and β-hydroxyketones with NaBH 4 in aqueous acetonitrile is highly stereoselective in the presence of stoichiometric amounts of bovine or human albumin, giving anti 1,3-diols with d.e. up to 96%. The same reaction, without albumin, gives syn and anti 1,3-diols in approximately 1:1 ratio. The presence of an aromatic carbonyl group is essential for diastereoselectivity in the NaBH4/albumin reduction of both 1,3-diketones and β-hydroxyketones. Thus, 3-hydroxy-1-(p-tolyl)-1- butanone is stereoselectively reduced in the presence of albumin, while reduction of its isomer 4-(p-tolyl)-4-hydroxy-2-butanone is not stereoselective. The albumin-controlled reduction is not stereospecific as both enantiomers of 1-aryl-3-hydroxy-1-butanones are reduced to diols with identical stereoselectivities. Circular dichroism of the bound substrates confirms that aromatic ketones are recognized by the protein's IIA binding site. Binding studies also suggest that 1,3-diketones are recognized in their enol form. From the effect of pH on binding of a diketone it is concluded that, in the complex with the substrate, ionizable residues His242 and Lys199 are in the neutral and protonated forms, respectively. A homology model of BSA was obtained and docking of model substrates confirms the preference of the protein for aromatic ketones. Modelling of the complexes with the substrates also allows us to propose a mechanism for the reduction of 1,3-diketones in which the chemoselective reduction of the first (aliphatic) carbonyl is followed by the diastereoselective reduction of the second (aromatic) carbonyl. The role of albumin is thus a combination of chemo- and stereocontrol.
- Berti, Federico,Bincoletto, Simone,Donati, Ivan,Fontanive, Giampaolo,Fregonese, Massimo,Benedetti, Fabio
-
experimental part
p. 1987 - 1999
(2011/04/25)
-
- Catalytic 1,3-difunctionalisation of organic backbones through a highly stereoselective, one-pot, boron conjugate-addition/reduction/oxidation process
-
A simple one-pot, three-step synthetic route to chiral 1,3-amino alcohols and 1,3-diols has been established. Considering the overall stereocontrol of the synthetic protocol, the first and key step is an enantioselective β-boration of α,β-unsaturated imin
- Sole, Cristina,Tatla, Amolak,Mata, Jose A.,Whiting, Andrew,Gulyas, Henrik,Fernandez, Elena
-
supporting information; experimental part
p. 14248 - 14257
(2012/01/19)
-
- A radical-anion chain mechanism following dissociative electron transfer reduction of the model prostaglandin endoperoxide, 1,4-diphenyl-2,3- dioxabicyclo[2.2.1]heptane
-
The model prostaglandin endoperoxide, 1,4-diphenyl-2,3-dioxabicyclo[2.2.1] heptane (3), was investigated in N,N-dimethylformamide at a glassy carbon electrode using various electrochemical techniques. Reduction of 3 occurs by a concerted dissociative electron transfer (ET) mechanism. Electrolysis at -1.6 V yields 1,3-diphenyl-cyclopentane-cis-1,3-diol in 97% by a two-electron mechanism; however, in competition with the second ET from the electrode, the resulting distonic radical-anion intermediate undergoes a β-scission fragmentation. The rate constant for the heterogeneous ET to the distonic radical-anion is estimated to occur on the order of 2 × 107 s-1. In contrast, electrolyses conducted at potentials more negative than -2.1 V yield a mixture of primary and secondary electrolysis products including 1,3-diphenyl-cyclopentane-cis-1,3-diol, 1,3-diphenyl-1,3-propanedione, trans-chalcone and 1,3-diphenyl-1,3-hydroxypropane by a mechanism involving less than one electron equivalent. These observations are rationalized by a catalytic radical-anion chain mechanism, which is dependent on the electrode potential and the concentration of weak non-nucleophilic acid. A thermochemical cycle for calculating the driving force for β-scission fragmentation from oxygen-centred biradicals and analogous distonic radical-anions is presented and the results of the calculations provide insight into the reactivity of prostaglandin endoperoxides.
- Magri, David C.,Workentin, Mark S.
-
body text
p. 3354 - 3361
(2009/02/05)
-
- 1,3-Diol synthesis via controlled, radical-mediated C-H functionalization
-
The invention of a method for the synthesis of 1,3-diols from the corresponding alcohols is described, via controlled, radical-mediated C-H functionalization. The sequence described herein entails near quantitative conversion to the corresponding trifluoroethyl carbamate, followed by a variant of the Hofmann-Loffler-Freytag reaction, cyclization, and hydrolysis to provide the 1,3-diols. In addition to the 10 examples presented herein, the syntheses of four natural products are facilitated by this directed oxyfunctionalization. This methodology is demonstrated to be orthogonal to other known C-H oxidations. Finally, this sequence is efficient, practical, inexpensive, and scalable. Copyright
- Chen, Ke,Richter, Jeremy M.,Baran, Phil S.
-
p. 7247 - 7249
(2008/12/21)
-
- Facile deoxygenation of dicarbonyl compounds using a samarium diiodide-additive system
-
The reduction of α- and β-dicarbonyl compounds was investigated with samarium diiodide in the presence of additive. Diketones and ketocarboxylic acids were easily reduced at room temperature to give the mono-alcohols in good to excellent yield, and ketoester afforded the saturated ester as the major product in moderate yield. These reductions containing the reductive deoxygenation can be rapidly performed under the facile and mild conditions by this method.
- Kamochi, Yasuko,Kudo, Tadahiro,Masuda, Toshinobu,Takadate, Akira
-
p. 1017 - 1020
(2007/10/03)
-
- Reduction of β-hydroxyketones by Sml2/H2O/ Et3N
-
(Chemical Equation Presented) Reduction of a series of β- hydroxyketones by Sml2/H2O/Et3N provided 1,3-diols in quantitative yields. The reactions were exceedingly clean with no byproduct formation, negating the need for f
- Davis, Todd A.,Chopade, Pramod R.,Hilmersson, Goeran,Flowers II, Robert A.
-
p. 119 - 122
(2007/10/03)
-
- Enantioselective borohydride reduction catalyzed by optically active cobalt complexes
-
The highly enantioselective borohydride reduction of aromatic ketones or imines to the corresponding alcohols was developed in the presence of a catalytic amount of an optically active cobalt(II) complex catalyst. This enantioselective reduction is carried out using a precisely premodified borohydride with alcohols such as tetrahydrofurfuryl alcohol, ethanol and methanol. High optical yields are obtained by choosing the appropriate alcohol as modifiers and a suitable β-ketoiminato ligand of the catalyst. The enantioselective borohydride reduction has been successfully applied to the preparation of optically active 1,3-diols, the stereoselective reduction of diacylferrocenes, and dynamic and/or kinetic resolution of 1,3-dicarbonyl compounds.
- Yamada, Tohru,Nagata, Takushi,Sugi, Kiyoaki D.,Yorozu, Kiyotaka,Ikeno, Taketo,Ohtsuka, Yuhki,Miyazaki, Daichi,Mukaiyama, Teruaki
-
p. 4485 - 4509
(2007/10/03)
-
- Albumin-controlled stereoselective reduction of 1,3-diketones to anti-diols
-
An unprecedented combination of high chemo- and stereoselectivity in the NaBH4 reduction of 1:1 complexes between albumin and aromatic 1,3-diketones results in the formation of anti 1,3-diols with de up to 96%.
- Benedetti, Fabio,Berti, Federico,Donati, Ivan,Fregonese, Massimo
-
p. 828 - 829
(2007/10/03)
-
- Practical synthesis of optically active amino alcohols via asymmetric transfer hydrogenation of functionalized aromatic ketones
-
2-Substituted acetophenones such as 2-cyano-, 2-azido-, or 2-nitroacetophenones were effectively reduced with a mixture of HCOOH/N(C2H5)3 containing a chiral Ru(II) catalyst, RuCl[(S,S)-N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine](p-cymene), giving the corresponding optically active alcohols, which can be converted to optically active amino alcohols with excellent ee's. Similarly, the reaction of 2-benzoylacetophenone with the same Ru catalyst gave a quantitative yield of the corresponding optically active 1,3-diol with 99% ee.
- Watanabe, Masahito,Murata, Kunihiko,Ikariya, Takao
-
p. 1712 - 1715
(2007/10/03)
-
- Facile reduction of aromatic aldehydes, ketones, diketones and oxo aldehydes to alcohols by an aqueous TiCl3/NH3 system: Selectivity and scope
-
A simple and rapid procedure for the almost quantitative reduction of aromatic aldehydes, ketones, diketones and oxo aldehydes to alcohols by use of TiCl3/NH3 in aqueous methanol solution is reported. The reducing system distinguishes between different classes of aldehydes and/or ketones, and many functionalities that usually do not survive under reducing conditions are tolerated well. The concept of reversal of chemoselectivity has also been developed. A mechanism based on two sequential one-electron transfers from TiIII to the carbonyl carbon atom is proposed, the second SET becoming operative only in the presence of ammonium ion (either added or formed in situ). Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
- Clerici, Angelo,Pastori, Nadia,Porta, Ombretta
-
p. 3326 - 3335
(2007/10/03)
-
- Ruthenium-catalyzed asymmetric reduction of 1,3-diketones using transfer hydrogenation
-
1,3-Diketones were reduced to 1,3-diols by using RuCl[N-(tosyl)-1,2-(diphenylethylenediamine) (η6-arene)] in the presence of formic acid and triethylamine. 1,3-Diols were obtained in good chemical yields and with high ee when symmetrical diketo
- Cossy, Janine,Eustache, Florence,Dalko, Peter I.
-
p. 5005 - 5007
(2007/10/03)
-
- A highly diastereoselective TiCl4-mediated reduction of β-hydroxy ketones with BH3·py - A very efficient and general synthesis of syn-1,3-diols
-
β-Hydroxy ketones can be reduced to the corresponding 1,3-diols in high yields and with excellent diastereoselectivity by carrying out the reaction with BH3·pyridine in CH2Cl2 at -78°C in the presence of TiCl4.
- Bartoli,Bosco,Marcantoni,Massaccesi,Rinaldi,Sambri
-
p. 4679 - 4684
(2007/10/03)
-
- Convenient preparation of optically pure 1,3-diaryl-1,3-propanediols
-
Optically pure 1,3-diaryl-1,3-propanediols were conveniently prepared from the corresponding 1,3-diketones by enantioselective borohydride reduction in the presence of a catalytic amount of β-ketoiminato cobalt(II) complexes.
- Ohtsuka, Yuhki,Kubota, Takeshi,Ikeno, Taketo,Nagata, Takushi,Yamada, Tohru
-
p. 535 - 537
(2007/10/03)
-
- TiCl4-mediated reduction of 1,3-diketones with BH3-pyridine complex: A highly diastereoselective method for the synthesis of syn-1,3-diols
-
(formula presented) 1,3-Diketones can be reduced in high yields and with excellent diastereoselectivity to the corresponding syn-1,3-diols by carrying out the reaction with BH3-pyridine complex in CH2Cl2 at -78°C in the pr
- Bartoli, Giuseppe,Bosco, Marcella,Bellucci, M. Cristina,Dalpozzo, Renato,Marcantoni, Enrico,Sambri, Letizia
-
-
- Reaction of α,β-unsaturated ketones with LiAlH4 under oxygen: Synthesis of 1,3-diols
-
1,3-Diols have been obtained by the reaction of α,β-unsaturated ketones with LiAlH4 in THF under a dry oxygen atmosphere.
- Csaky, Aurelio G.,Maximo, Natalia,Plumet, Joaquin,Ramila, Ainhoa
-
p. 6485 - 6487
(2007/10/03)
-
- Diastereoselectivity in the reduction of acyclic carbonyl compounds with diisopropoxytitanium(III) tetrahydroborate
-
Diisopropoxytitanium(III) tetrahydroborate, ((i)PrO)2TiBH4, formed in situ in dichloromethane from diisopropoxytitanium dichloride and benzyltriethylammonium tetrahydroborate (1:2) reduces α-hydroxyketones/1,2- diketones and β-hydroxyketones/1,3-diketones to the corresponding diols with high stereoselectivity. In the case of α-hydroxyketones and 1,2-diketones, the anti isomer is the major product while reduction of β-hydroxyketones and 1,3-diketones leads to the syn isomer as the major product.
- Ravikumar,Sinha, Surajit,Chandrasekaran
-
p. 5841 - 5844
(2007/10/03)
-
- Functionalized organolithium compounds of DTBB-catalyzed sulfur-lithium exchange
-
The successive reaction of β- or γ-hydroxy or amino phenyl thioethers (1,4) with butyllithium and an excess of lithium powder in the presence of a catalytic amount of DTBB in THF at - 78°C leads to the formation of the corresponding β- or γ-functionalized organolithium compounds 2 or 5, respectively, which by treatment with different electrophiles [D2O, t- BuCHO, PhCHO, Me2CO, (CH2)4CO, (CH2)5CO] at temperatures ranging between - 78°C and room temperature yields, after hydrolysis with water, the expected functionalized alcohols or amines 3 or 6, respectively, in a completely regioselective manner.
- Foubelo, Francisco,Gutiérrez, Ana,Yus, Miguel
-
p. 503 - 514
(2007/10/03)
-
- Diastereoselective reduction of β-hydroxyketones with amineboranes in the presence of lithium perchlorate
-
The reduction of β-hydroxyketones with amineboranes in the presence of lithium perchlorate produces the corresponding anti 1,3-diols as major products.
- Narayana, Chatla,Reddy, M. Rama,Hair, Max,Kabalka, George W.
-
p. 7705 - 7708
(2007/10/03)
-
- In search of open-chain 1,3-stereocontrol
-
Methylation of methyl 4-phenylpentanoate 25 gives the diastereoisomers methyl (2RS,4SR)-2-methyl-4-phenylpentanoate 26 and methyl (2RS,4RS)- 2-methyl-4-phenylpentanoate 27 in a ratio of 44:56. The aldehydes 3-dimethyl(phenyl)silylbutanal 28, 3-dimethyl(ph
- Barbero, Asun,Blakemore, David C.,Fleming, Ian,Wesley, Robert N.
-
p. 1329 - 1352
(2007/10/03)
-
- β-Functionalised organolithium compounds through a sulfur-lithium exchange
-
The successive reaction of different β-hydroxy or β-amino tbioethers 1a-d with n-butyl-lithium and an excess of lithium powder and a catalytic amount of DTB in THF at -78°C leads to the formation of the corresponding β-functionalised organolithium compounds 2a-d, which by reaction with several electrophiles [D2O, Bu(t)CHO, PhCHO, Me2CO, (CH2)5CO] at temperatures ranging between -78 and 20°C yields, after hydrolysis with water, the expected functionalised alcohols or amines 3aa-de in a regioselective manner.
- Foubelo, Francisco,Gutierrez, Ana,Yus, Miguel
-
p. 4837 - 4840
(2007/10/03)
-
- Diastereoselective reduction of acyclic hydroxyketones and diketones with an indium hydride reagent
-
Hydroxyketones and diketones have been reduced with lithium indium hydride to give meso-diols selectively. α-Hydroxyketones and α-diketones are reduced to meso-1,2-diols with high diastereoselectivities, whereas the selectivities of β-hydroxyketones and β-diketones are less satisfactory.
- Yamada, Masafumi,Horie, Tomoaki,Kawai, Masao,Yamamura, Hatsuo,Araki, Shuki
-
p. 15685 - 15690
(2007/10/03)
-
- Stereocontrolled reductive amination of 3-hydroxy ketones
-
syn-1,3-Aminoalcohols are synthesized in high diastereomeric excess by reductive amination of 3-hydroxyketones with sodium cyanoborohydride in the presence of benzylamine.
- Haddad, Mansour,Dorbais, Jerome,Larcheveque, Marc
-
p. 5981 - 5984
(2007/10/03)
-
- Design, reactivities, and practical application of dialkylzinc hydride ate complexes generated in Situ from dialkylzinc and metal hydride. A new methodology for activation of NaH and LiH under mild conditions
-
We designed various dialkylzinc hydride 'ate' complexes, prepared from dialkylzinc and metal hydride, and investigated the reactivities (and the transference aptitude of ligands) of these zincates toward benzophenone. The results clearly reveal that dimethylzinc hydrides are the most powerful and selective zincates for the reduction of the carbony1 group. This complex reagent turned out to be effective for the reduction of esters and amides as well as aldehydes and ketones to the corresponding alcohols and amines with good to excellent yields under mild conditions. Furthermore, the method was successfully used for the highly selective 1,2-reduction of α,β-unsaturated carbonyl compounds, the regioselective ring-opening reduction of epoxides, and the chemoselective reduction of aldehydes in the presence of ketones. We also discuss and clarify the active species and the mechanism of this reduction using the diastereoselective reductions of some carbonyl compounds with an adjacent chiral center. Also, this reducing system was found to constitute a powerful tool for the stereoselective synthesis of syn- and anti-1,2-diols. Moreover, we developed the catalytic version of this reducing system. The LiH-Me2Zn-ultrasound system proved to be effective not only for the catalytic reduction of the carbonyl compounds and epoxides but also for the partial reduction (the conversion) of carboxylic acids to aldehydes. This system is a very attractive method for several reasons (good availability, low cost, and easy operation) and would be particularly useful for large- scale reductions.
- Uchiyama, Masanobu,Furumoto, Shozo,Saito, Mariko,Kondo, Yoshinori,Sakamoto, Takao
-
p. 11425 - 11433
(2007/10/03)
-
- Intrazeolite photochemistry. 14. Photochemistry of α,ω-diphenyl allyl cations within zeolites
-
1,3-Diphenylpropenylium (DP3+) and 1,5-diphenylpentadienylium (DP5+) ions have been generated within acid ZSM-5 and mordenite zeolites as persistent species by adsorption of α,ω-disubstituted α,ω-diphenylalkanes. It was found that be
- Garcia, Hermenegildo,Garcia, Sara,Perez-Prieto, Julia,Scaiano
-
p. 18158 - 18164
(2007/10/03)
-
- Stereoselective reduction of β-hydroxy ketones to 1,3-diols with the aid of a terphenylboronic acid
-
1-Hydroxy-6,8-diphenyl-1,2,3,4-tetrahydro-2-oxa-1-boranaphthalene (terphenylboronic acid 1), is employed for stereo-selective reduction of acyclic and cyclic β-hydroxy ketones. The terphenylboronic acid 1 and acyclic β-hydroxy ketones 2 are converted to t
- Yamashita, Hiroshi,Narasaka, Koichi
-
p. 539 - 540
(2007/10/03)
-
- BCl3- and TiCl4-mediated reductions of β-hydroxy ketones
-
Syn-selective reduction protocols for β-hydroxy ketones are described exploiting the intermediacy of titanium and boron chelates derived from TiCl4 and BCl3, respectively. Reductions are conducted at -78°C in CH2Cl2/
- Sarko, Christopher R.,Collibee, Scott E.,Knorr, Allison L.,DiMare, Marcello
-
p. 868 - 873
(2007/10/03)
-
- Enzyme catalysed resolution of 1,3-diarylpropan-1,3-diols
-
Candida Rugosa Lipase (AY 30, Amano) is shown to be a very efficient catalyst for the resolution of enantiomeric 1,3-diaryl-1,3-diols by means of the transesterification reaction using vinyl acetate as an acyl donor. This enzyme also exerts a great diater
- Levayer,Rabiller,Tellier
-
p. 1675 - 1682
(2007/10/02)
-
- Fluoride Ion Catalyzed Reduction of Aldehydes and Ketones with Hydrosilanes. Synthetic and Mechanistic Aspects and an Application to the Threo-Directed Reduction of α-Substituted Alkanones
-
Reduction of aldehydes and ketones with hydrosilanes proceeded in the presence of a catalytic amount of tetrabutylammonium fluoride or tris(diethylamino)sulfonium difluorotrimethylsilicate in aprotic polar solvents under mild conditions.A significant isotope effect (kH/kD = 1.50) was observed in competitive reduction of acetophenone with HSiMe2Ph and DSiMe2Ph.The reaction was of first order in the concentration of an aprotic polar solvent HMPA.Reduction of 2-methylcyclohexanone gave cis-2-methylcyclohexanol with selectivities up to 95percent.The kinetic and stereochemical results suggest that a hexavalent fluorosilicate - is involved. α-Alkoxy (acyloxy or dimethylamino) ketones were transformed to threo alcohols in high diastereoselectivities.The reduction was also applied to α-methyl-β-keto amides, RCOCH(MeCONR)2, to afford the corresponding threo alcohols in >98percent selectivity.The threo selectivity is explained in terms of the Felkin-Anh model in which interaction of carbonyl oxygen with a countercation is ideally suppressed.The threo-directed reduction was applied to (R)-1-phenyl-4-(2-tetrahydropyranyloxy)-1-penten-3-one and N-(2-benzoylpropanoyl)piperidine.The resulting threo alcohols were respectively converted into (2R,3S)-2,3-(cyclohexylidenedioxy)butanal, a key intermediate of daunosamine synthesis, and into a pharmacologically useful compound threo-N-(3-hydroxy-2-methyl-3-phenylpropyl)piperidine.
- Fujita, Makoto,Hiyama, Tamejiro
-
p. 5405 - 5415
(2007/10/02)
-
- METHOXYCHLORINATION AND DIMETHOXYLATION OF ALKENES. THE REACTIONS OF SUBSTITUTED STYRENES WITH PHENYLSELENENYL CHLORIDE IN METHANOL
-
The addition of PhSeCl to α- and β-substituted styrenes in methanol is regio- and stereospecific and affords the products of methoxyselenenylation.These compounds further react with PhSeCl to give the deselenenylation products.In the case of α-substituted styrenes, 1-methoxy, 2-chloroalkanes are produced, whereas with β-substituted styrenes the major reaction products are the 1,2-dimethoxyalkanes and the 2,2-dimethoxyalkanes in which phenyl migration has occured.It is shown that these reactions proceed through the intermediate formation of the alkyl phenylselenium dichlorides, PhCR(OMe)CHR1SeCl2Ph, which evolve with different mechanisms depending on the structure of the starting alkenes.
- Tiecco, Marcello,Testaferri, Lorenzo,Tingoli, Marco,Chianelli, Donatella,Bartoli, Donatella
-
p. 2261 - 2272
(2007/10/02)
-
- 1,3-SYN DIASTEREOSELECTIVE REDUCTION OF β-HYDROXYKETONES UTILIZING ALKOXYDIALKYLBORANES
-
Sodium borohydride reduction of β-hydroxyketones in presence of alkoxydialkylboranes 1-7 as complexing agents, produced 1,3-syn diols in at least 98:2 ratio.As illustrated with examples 8-17 this method is quite general and superior to those described in
- Chen, Kau-Ming,Hardtmann, Goetz E.,Prasad, Kapa,Repic, Oljan,Shapiro, Michael J.
-
p. 155 - 158
(2007/10/02)
-
- DIASTEREOSELECTIVE CONJUGATE ADDITION TO CHIRAL α,β ETHYLENIC ACETALS
-
The phenyl copper reagent associated with Lewis acid (BF3) reacts regio (SN2') and stereoselectively with chiral α,β ethylenic acetals.
- Mangeney, P.,Alexakis, A.,Normant, J. F.
-
p. 3143 - 3146
(2007/10/02)
-
- TRANSFORMATIONS OF PHENYLCYCLOPROPANES UNDER THE INFLUENCE OF VARIOUS DIACYLOXYIODO DERIVATIVES
-
The reaction of phenylcyclopropanes with various (diacycloxyiodo)benzenes and iodine tristrifluoracetate was studied. (Bistrichloroacetoxyiodo)benzene and (bistrifluoracetoxyiodo)benzene react with phenylcyclopropanes exclusively in the small ring with the formation of the respective 1-phenyl-1,3-bis(acyloxy)propanes.Iodine tristrifluoroacetate in reaction with phenylcyclopropanes attacks both the small ring and the aromatic ring, which leads to the production of the esters of 1,3-diols and p-iodophenylcyclopropanes.Possible mechanisms are proposed for the oxidative cleavage of the trimethyl ring of phenylcyclopropanes.
- Saginova, L. G.,Bondarenko, O. B.,Gazzaeva, R. A.,Shabarov, Yu. S.
-
p. 477 - 480
(2007/10/02)
-
- STEREOSELECTIVE REDUCTION OF β-HYDROXYKETONES TO 1,3-DIOLS. HIGHLY SELECTIVE 1,3-ASYMMETRIC INDUCTION VIA BORON CHELATES
-
Highly selective asymmetric induction can be achieved in the reduction of acyclic β-hydroxyketones via boron chelates.Treatment of β-hydroxyketones (1) with tributyl or triisobutylborane and successively with sodium borohydride afforded syn-1,3-diols (3)
- Koichi, Narasaka,Pai, Fong-Chang
-
p. 2233 - 2238
(2007/10/02)
-
- β-Substituted Organolithium Compounds from Chlorohydrins: Application to the Direct Synthesis of Bifunctionalized Organic Cpmpounds
-
The reaction of different chlorohydrins with n-butyl-lithium at -78 deg C followed by metallation wiht lithium naphthalenide at the same temperature leads to very reactive organolithium compounds bearing an alkoxide function at the β-position with respect to metal.The reaction of these intermediates with several electriphiles leads to mono- as well as bi-functionalized organic compounds.Thus, treatment of these dianions with deuterium oxide, oxygen, carbon dioxide, benzyl bromide, dimethyl disulphide, and carbonyl compounds, gave 2-deuterioalcohols, 1,2-diols, β-hydroxy-acids, 2-benzyl alcohols, 2-hydroxy-thioethers, and 1,3-diols respectively.The preparation of β-substituted organolithium derivatives can be alternatively carried out starting from α-chloroketones by the same procedure.When the lithium atom is linked to a secondary carbon atom the dianions are very unstable and decompose, even at -100 deg C, by β-elimination yielding the corresponding olefins.
- Barluenga, Jose,Florez, Josefa,Yus, Miguel
-
p. 3019 - 3026
(2007/10/02)
-
- Effect of Restricted Mobility of the Linking Chain on Intramolecular Excimer Formation
-
Intramolecular excimer formation in a series of phenyl-substituted 1,3-propanediols, compounds in which the motions of the linking chain are restricted by intramolecular hydrogen bonding, was investigated under stationary conditions in n-hexane.The excime
- Todesco, R.,Bockstaele, D. Van,Gelan, J.,Martens, H.,Put, J.,Schryver, F. C. De
-
p. 4963 - 4968
(2007/10/02)
-
- β-Substituted Organolithium Compounds; Direct Preparation and Reactivity
-
Very reactive organolithium compounds bearing an alkoxide function at the β-position with respect to the metal are obtained by direct metallation with lithium naphthalenide at low temperature of the corresponding lithium chlorohydrin salt; the reaction of these dianions with different electrophilic agents leads to the corresponding mono- and bi-functionalized compounds.
- Barluenga, Jose,Florez, Josefa,Yus, Miguel
-
p. 1153 - 1154
(2007/10/02)
-
- The Mechanism of Asymmetric Hydrogenation. Chiral Bis(diphenylphosphino)-α-phenylalkane Complexes in Catalytic and Structural Studies
-
(R)-1,2-Bis(diphenylphosphino)phenylethane has been synthesised in good overall yield from (S)-mandelic acid ; its cationic rhodium(I) solvated complex has been shown to be effective in catalytic asymmetric hydrogenation with optical yields of up to 88percent having been observed.The n.m.r. spectra of complexes of this phosphine are discussed.Racemic (R*,R*)-1,3-bis(diphenylphosphino)-1,3-diphenylpropane and (R*,R*)-1,4-bis(diphenylphosphino)-1,4-diphenylbutane have been prepared.These form a range of rhodium complexes with dehydroamino-acids whose structures may be assigned on the basis of characteristic n.m.r.P-Rh and P-P coupling constants.
- Brown, John M.,Murrer, Barry A.
-
p. 489 - 498
(2007/10/02)
-