cas 6999-19-5, 4-TRIMETHYLSILYL-3-BUTYN-2-OL

Articles about 6999-19-5Total 56 be found

Article title
Article abstract
Author
Journal number and time
Download

Propargylation of CoQ0 through the Redox Chain Reaction
An efficient catalytic propargylation of CoQ0 is described by employing the cooperative effect of Sc(OTf)3 and Hantzsch ester. It is suggested to work through the redox chain reaction, which involves hydroquinone and dimeric propargylic moiety intermediates. A broad range of propargylic alcohols can be converted into the appropriate derivatives of CoQ0 containing triple bonds in good to excellent yields. The mechanism of the given transformation is also discussed.
Pawlowski, Robert,Stodulski, MacIej,Mlynarski, Jacek
p. 683 - 692
(2022/01/04)

A boron-oxygen transborylation strategy for a catalytic midland reduction
The enantioselective hydroboration of ketones is a textbook reaction requiring stoichiometric amounts of an enantioenriched borane, with the Midland reduction being a seminal example. Here, a turnover strategy for asymmetric catalysis, boron.oxygen transb
Nicholson, Kieran,Dunne, Joanne,DaBell, Peter,Garcia, Alexander Beaton,Bage, Andrew D.,Docherty, Jamie H.,Hunt, Thomas A.,Langer, Thomas,Thomas, Stephen P.
p. 2034 - 2040
(2021/02/20)

Towards the Total Synthesis of Jerangolids – Synthesis of an Advanced Intermediate for the Pharmacophore Substructure
The jerangolids are a class of natural products with a skipped diene substructure isolated from Sorangium cellulosum. Here, we present a new strategy for the total synthesis of these compounds based on a skipped diyne as central building block and a suitably substituted epoxy aldehyde as building block for the dihydropyran substructure. So far, we reached an advanced intermediate which is related to the pharmacophore subunit of the jerangolids as well as of the ambruticins. A key step is a Shi epoxidation with high e.r. to form the epoxy aldehyde. Both building blocks are coupled in a Carreira alkynylation, where additional mechanistic studies based on DFT calculation were realized. The alkynylation is followed by a nucleophilic 6-endo-tet epoxide opening to form the pyran structure and a Nicholas reduction to remove a propargylic OH group.
Huch, Volker,Hutter, Michael,Jauch, Johann,Lenhof, Julian
p. 5833 - 5840
(2020/09/22)

Asymmetric Magnesium-Catalyzed Hydroboration by Metal-Ligand Cooperative Catalysis
Asymmetric catalysis with readily available, cheap, and non-toxic alkaline earth metal catalysts represents a sustainable alternative to conventional synthesis methodologies. In this context, we describe the development of a first MgII-catalyzed enantioselective hydroboration providing the products with excellent yields and enantioselectivities. NMR spectroscopy studies and DFT calculations provide insights into the reaction mechanism and the origin of the enantioselectivity which can be explained by a metal-ligand cooperative catalysis pathway involving a non-innocent ligand.
Falconnet, Alban,Magre, Marc,Maity, Bholanath,Cavallo, Luigi,Rueping, Magnus
supporting information
p. 17567 - 17571
(2019/11/13)

Phosphine-Catalyzed Intermolecular Annulations of Fluorinated ortho-Aminophenones with Alkynones – The Switchable [4+2] or [4+2]/[3+2] Cycloaddition
A phosphine-catalyzed intermolecular annulation reaction of functionalized ortho-aminoacetophenones with alkynones has been disclosed in this paper. A variety of 2-alkynylquinolines and benzo-fused indolizine were selectively afforded in moderate to good yields at different reaction temperatures and with different phosphine catalysts via the in situ generated zwitterionic intermediate derived from alkynone and phosphine. (Figure presented.).
Zhang, Yanshun,Sun, Yaoliang,Wei, Yin,Shi, Min
supporting information
p. 2129 - 2135
(2019/03/13)

Unprecedented Stereocontrol in the Synthesis of 1,2,3-Trisubstituted Tetrahydro-β-carbolines through an Asymmetric Pictet–Spengler Reaction towards Sarpagine-Type Indole Alkaloids
The asymmetric Pictet–Spengler (P-S) reaction of chiral Nb-ethynyl-substituted tryptophan methyl ester derivatives (from both d- and l-tryptophan) with a simple aliphatic aldehyde, exhibited unprecedented selectivity towards either of the diastereomeric products. A simple variation of conditions could alter the outcome of the cyclization from either 100 % trans-selective to 100 % cis-selective originating entirely from internal asymmetric induction under mild conditions. This resulted in a highly efficient access to both 1,3-cis-(1,2,3-trisubstituted tetrahydro-β-carbolines, THβCs) and 1,3-trans-(1,2,3-trisubstituted THβCs). To the best of our knowledge, this type of stereocontrol has never been observed from tryptophan methyl ester derivatives (either D or L) in accessing either 1,3-disubstituted or 1,2,3-trisubstituted THβCs. By exploiting this very useful ambidextrous diastereoselectivity, we have set the crucial C-3 and C-5 stereocenters of C-19 methyl-substituted sarpagine/macroline/ajmaline alkaloids beginning with the DNA-encoded and cheaper l-(–)-tryptophan, as well as optionally from commercially available d-(+)-tryptophan.
Rahman, M. Toufiqur,Cook, James M.
supporting information
p. 3224 - 3229
(2018/07/06)

Chiral crotyl geminal bis(silane): a useful reagent for asymmetric Sakurai allylation by selective desilylation-enabled chirality transfer
Enantioselective synthesis of SiMe3/SiPh2Me-substituted crotyl geminal bis(silane) has been developed. This compound is a useful reagent for Ph3C+B(C6F5)4--catalyzed asymmetric Sakurai allylation and one-pot Sakurai allylation/Prins cyclization processes. Chemoselective desilylation of SiPh2Me leads to efficient chirality transfer.
Chu, Zhiwen,Wang, Kai,Gao, Lu,Song, Zhenlei
supporting information
p. 3078 - 3081
(2017/03/17)

Cobalt-catalyzed carboxylation of propargyl acetates with carbon dioxide
The cobalt-catalyzed carboxylation of propargyl acetates with CO2 (1 atm) is described. The reaction proceeds at room temperature in the presence of Mn powder as a reducing reagent. Various propargyl acetates are converted to the corresponding carboxylic acids in good to high yields.
Nogi, Keisuke,Fujihara, Tetsuaki,Terao, Jun,Tsuji, Yasushi
supporting information
p. 13052 - 13055
(2015/02/19)

Response surface methodology as an optimization strategy for the light-controlled asymmetric hydrogenation of 4-(trimethylsilyl)-3-butyn-2-one by photosynthetic bacteria
Enantiomerically pure (S)-4-(trimethylsilyl)-3-butyn-2-ol {(S)-TMSBL} is a key intermediate for the synthesis of many biologically and structurally interesting compounds and pharmaceuticals. Herein we propose a new light-controlled asymmetric hydrogenation of 4-(trimethylsilyl)-3-butyn-2-one (TMSBO) to enantiopure (S)-TMSBL by photosynthetic bacteria Rhodobacter sphaeroides, which is a newly isolated photosynthetic bacteria strain that has the capacity to capture light energy and to generate NADPH through photosynthetic electron-transfer reactions; no oxygen or other metabolic intermediates were used. Response Surface Methodology (RSM) was used to investigate the effects of substrate concentration, pH, and temperature on the reaction yield. A 33 factorial design was performed to optimize the production of (S)-TMSBL. The optimum conditions were: cell concentration (200 g/L), shaking speed (140 rpm), pH (6.9), substrate concentration (14.4 mmol/L), and temperature (33.6 °C). This optimization strategy led to an increase of the yield from 88.9% to 94.5%.
Rui-Hu,Xu, Yun-Sheng,Shao, Dong-Xu,Wang, Meng-Liang
p. 81 - 88
(2013/04/23)

Trifluoromethylation of allylsilanes under photoredox catalysis
A new catalytic method to access allylic secondary CF3 products is described. These reactions use the visible light excited Ru(bpy) 3Cl2·6H2O catalyst and the Togni or Umemoto reagent as the CF3 source. The photoredox catalytic manifold delivers enantioenriched allylic trifluoromethylated products not accessible under Cu(I) catalysis.
Mizuta, Satoshi,Engle, Keary M.,Verhoog, Stefan,Galicia-López, Oscar,O'Duill, Miriam,Médebielle, Maurice,Wheelhouse, Katherine,Rassias, Gerasimos,Thompson, Amber L.,Gouverneur, Véronique
supporting information
p. 1250 - 1253
(2013/05/09)

Asymmetric catalytic alkynylation of acetaldehyde: Application to the synthesis of (+)-tetrahydropyrenophorol
In control: By controlling the kinetics of alkynylation over aldolization, the challenging asymmetric catalytic alkynylation of acetaldehyde has been realized. The resulting products are attractive synthons which are produced with good to excellent enanti
Trost, Barry M.,Quintard, Adrien
supporting information; experimental part
p. 6704 - 6708
(2012/09/22)

Cyclopropane compatibility with oxidative carbocation formation: Total synthesis of clavosolide A
Cyclopropane-substituted allylic ethers react with 2,3-dichloro-5,6- dicyano-1,4-benzoquinone to form oxocarbenium ions with no competitive ring cleavage. This reaction can be used for the preparation of cyclopropane- substituted tetrahydropyrans. The pro
Peh, Guangrong,Floreancig, Paul E.
supporting information
p. 5614 - 5617,4
(2012/12/13)

Nickel-catalyzed enantioselective cross-couplings of racemic secondary electrophiles that bear an oxygen leaving group
To date, effective nickel-catalyzed enantioselective cross-couplings of alkyl electrophiles that bear oxygen leaving groups have been limited to reactions of allylic alcohol derivatives with Grignard reagents. In this Communication, we establish that, in the presence of a nickel/pybox catalyst, a variety of racemic propargylic carbonates are suitable partners for asymmetric couplings with organozinc reagents. The method is compatible with an array of functional groups and utilizes commercially available catalyst components. The development of a versatile nickel-catalyzed enantioselective cross-coupling process for electrophiles that bear a leaving group other than a halide adds a significant new dimension to the scope of these reactions.
Oelke, Alexander J.,Sun, Jianwei,Fu, Gregory C.
supporting information; experimental part
p. 2966 - 2969
(2012/04/04)

Palladacycle-catalyzed reaction of bicyclic alkenes with terminal ynones: Regiospecific synthesis of polysubstituted furans
A new synthetic strategy to access polysubstituted furans regiospecifically has been developed using simple bicyclic alkenes and terminal ynones as starting materials with palladacycles as unique active catalysts. A rational mechanism has also been proposed. This reaction features mild reaction conditions, easily available starting materials and palladacycle catalysts, a wide substrate scope, and high regiospecificity.
Ge, Guang-Cun,Mo, Dong-Liang,Ding, Chang-Hua,Dai, Li-Xin,Hou, Xue-Long
supporting information
p. 5756 - 5759
(2013/01/15)

On the stereochemical course of palladium-catalyzed cross-coupling of allylic silanolate salts with aromatic bromides
The stereochemical course of palladium-catalyzed cross-coupling reactions of an enantioenriched, a-substituted, allylic silanolate salt with aromatic bromides has been investigated. The allylic silanolate salt was prepared in high geometrical (Z/E, 94:6) and high enantiomeric (94:6 er) purity by a coppercatalyzed SN2′ reaction of a resolved allylic carbamate. Eight different aromatic bromides underwent crosscoupling with excellent constitutional site-selectivity and excellent stereospecificity. Stereochemical correlation established that the transmetalation event proceeds through a syn SE′ mechanism which is interpreted in terms of an intramolecular delivery of the arylpalladium electrophile through a key intermediate that contains a discrete Si-O-Pd linkage.
Denmark, Scott E.,Werner, Nathan S.
scheme or table
p. 3612 - 3620
(2010/05/01)

Improved method for the synthesis of β-carbonyl silyl-1,3-dithianes by the double conjugate addition of 1,3-dithiol to propargylic carbonyl compounds
(Chemical Equation Presented) Base-mediated double conjugate addition of 1,3-propane dithiol to various silylated propargylic aldehydes and ketones allows for an efficient and scalable synthesis of β-carbonyl silyl-1,3-dithianes.
Mukherjee, Sumit,Kontokosta, Dimitra,Patil, Aditi,Rallapalli, Sivakumar,Lee, Daesung
supporting information; experimental part
p. 9206 - 9209
(2010/03/02)

Nickel-catalyzed asymmetric cross-couplings of racemic propargylic halides with arylzinc reagents
A stereoconvergent method for the catalytic asymmetric Negishi cross-coupling of racemic secondary propargylic halides with arylzinc reagents has been developed. Neither family of compounds has previously been shown to be a suitable partner in such coupling processes. From a practical point of view, it is noteworthy that the catalyst components (NiCl2·glyme and pybox ligand 1) are commercially available. Copyright
Smith, Sean W.,Fu, Gregory C.
supporting information; experimental part
p. 12645 - 12647
(2009/05/09)

Crotylation versus propargylation: Two routes for the synthesis of the C13-C18 fragment of the antibiotic branimycin
The C13-C18 fragment 3 of the novel antibiotic branimycin was prepared along two highly stereocontrolled routes. The first one uses a standard Roush crotylation protocol, whereas the second one proceeds via an allenyl silane propargylation with unexpected stereochemical consequences, which are discussed in detail.
Felzmann, Wolfgang,Castagnolo, Daniele,Rosenbeiger, Daniela,Mulzer, Johann
p. 2182 - 2186
(2007/10/03)

Synthesis of (arylalkenyl)silanes by palladium-catalyzed regiospecific and stereoselective allyl transfer from silyl-substituted homoallyl alcohols to aryl halides
The reactions of silyl-substituted homoallyl alcohols with aryl halides under palladium catalysis result in regiospecific and stereoselective allyl transfer from the alcohols to aryl halides, offering modular synthesis of (E)-3-aryl-1-alkenyl-, (E)-1-aryl-2-alkenyl-, and optically active (E)-1-aryl-2-butenylsilanes. Copyright
Hayashi, Sayuri,Hirano, Koji,Yorimitsu, Hideki,Oshima, Koichiro
p. 12650 - 12651
(2008/03/14)

Cu-catalyzed asymmetric conjugate additions of dialkyl- and diarylzinc reagents to acyclic β-silyl-α,β-unsaturated ketones. Synthesis of allylsilanes in high diastereo- and enantiomeric purity
A readily available and simple (MW = 444.5 g/mol) valine-based chiral phosphine is used to promote highly efficient catalytic asymmetric conjugate additions of dialkyl- and diarylzinc reagents to acyclic β-silyl-α, β-unsaturated ketones. The catalytic asy
Kacprzynski, Monica A.,Kazane, Stephanie A.,May, Tricia L.,Hoveyda, Amir H.
p. 3187 - 3190
(2008/02/11)

Selective synthesis of epolactaene featuring efficient construction of methyl (Z)-2-iodo-2-butenoate and (2R,3S,4S)-2-trimethylsilyl-2,3-epoxy-4- methyl-γ-butyrolactone
(+)-Epolactaene was synthesized in 14 steps in the longest linear sequence. The synthesis is highlighted by a highly efficient preparation of the lactone intermediate 4, which only requires three steps from the commercially available (S)-3-butyn-2-ol. It also features a fully stereocontrolled synthesis of the intermediate 9, which was constructed through the use of Zr-catalyzed methylalumination of alkynes and a series of Pd-catalyzed organozinc cross-coupling reactions, such as homopropargylation, direct ethynylation, and alkenylation of the methyl ester of (Z)-α-iodocrotonic acid (3).
Tan, Ze,Negishi, Ei-Ichi
p. 2783 - 2785
(2007/10/03)

A pentenyl dianion-based strategy for convergent synthesis of ene-1,5-diols
A convergent two-step process is described for the synthesis of ene-1,5-diols that provides for union of two carbonyl electrophiles via a formal pentenyl dianion equivalent. Copyright
Bahadoor, Adilah B.,Flyer, Alec,Micalizio, Glenn C.
p. 3694 - 3695
(2007/10/03)

Lipase-catalyzed resolution of 4-trimethylsilyl-3-Butyn-2-OL and conversion of the (R)-enantiomer to (R)-3-butyn-2-YL mesylate and (P)-1-tributylstannyl-1,2-butadiene: [3-Butyn-2-ol, 4-(trimethylsilyl)-, (2R)- and Stannane, 1,2-butadienyltributyl-, (P)-]
-
Marshall, James A.,Chobanian, Harry,Wipf, Peter,Pierce, Joshua
p. 43 - 54
(2017/10/05)

Accurate determinations of the extent to which the SE2′ reactions of allyl-, allenyl- and propargylsilanes are stereospecifically anti
The allylsilanes, (R)-E- and (R)-Z-4-trimethylsilylpent-2-ene 16, were prepared in essentially an enantiomerically and geometrically pure state (er >99.95 : 0.05, E : Z and Z : E >99.95 : 0.05) by, successively, conjugate addition of lithium dimethylcuprate to N-[(E)-3′-trimethylsilylpropenoyl]-(7S)-10, 10-dimethyl-4-aza-5-thiatricyclo[5.2.1.03,7]-decane 5,5-dioxide, to give N-[(E)-(3′ R)-3′-trimethylsilylbutanoyl]-(7S)-10, 10-dimethyl-4-aza-5-thiatricyclo[5.2.1.03,7]decane 5,5-dioxide 13, removal of the chiral auxiliary with bromomagnesium benzyloxide, aldol reaction with acetaldehyde, and decarboxylative elimination, to give either the Z- or E-isomer. Both the E- and Z-allylsilanes 16 reacted with the adamantyl cation to give mixtures of E- and Z-4-adamantylpent-2-enes 17. The E-allylsilane gave the E- and Z-products in a ratio of 40 : 60, and the Z-allylsilane gave the E- and Z-products in a ratio of 99.8 : 0.02. The enantiomer ratio was >99 : 1 for the reaction of the E-allylsilane giving the Z-product, 90 : 10 for the E-allylsilane giving the E-product, and 95 : 5 for the Z-allylsilane giving the E-product, showing that the reactions were stereospecific to a high degree, but not always quite completely so. The allenylsilane, 2-trimethylsilylpenta-2,3-diene 29, was prepared enantiomerically highly enriched (er 99 : 1) by copper-catalysed reaction of methylmagnesium chloride with (S)-4-trimethylsilylbut-3-yn-2-yl camphor-10-sulfonate 28. The allenylsilane 29 reacted with the adamantyl cation to give (S)-4-adamantylpent-2-yne (S)-30 with the same level of enantiomeric purity, showing that the reaction was, as accurately as can be measured, completely stereospecific. The allenylsilane 29 also reacted with isobutanal in the presence of titanium tetrachloride to give 2,4-dimethylhept-5-yn-3-ol as a mixture of diastereoisomers, syn 31 and anti 32, in a ratio of 95 : 5, with the major diastereoisomer present as a mixture of enantiomers (4R,5R) : (4S,5S) in a ratio of 99 : 1, showing that the reaction was, as accurately as can be measured, completely stereospecific in the anti sense. The corresponding propargylsilane, 4-trimethylsilylpent-2-yne 37, reacted with the adamantyl cation to give dienes assigned the structures 2,3-diadamantyl-1,3-pentadiene 42 and 2,4-diadamantyl-1,3-pentadiene 43, and reacted with isobutanal in the presence of titanium tetrachloride to give 2-(1-hydroxy-2-methylpropyl)-3-trimethylsilylpenta-1,3-dienes 45 and 2,4-dimethyl-5-trimethylsilylhept-5-en-3-one 46. The enantiomerically enriched propargylsilane (R)-1,3-bis(trimethylsilyyl)but-1-yne 62 (er >99.7 : 0.3) was prepared from the sultam 13, by removal of the chiral auxiliary with lithium ethoxide, reduction of the ethyl ester to give (R)-3-trimethylsilylbutanal 60, enol triflate formation, β-elimination and C-silylation. The propargylsilane 62 reacted with 2,4-dinitrobenzaldehyde in the presence of titanium tetrachloride to give the allenes, 1-(2,4-dinitrophenyl)-2-trimethylsilylpenta-2,3-dienols 63-66, as two diastereoisomers in a ratio of 2 : 1, each of which was a pair of enantiomers in a ratio of approximately 3 : 1, showing that there was considerable loss of stereospecificity, but that what there was in the anti sense. A similar reaction with isobutanal gave a similar set of four allenes, 2-methyl-4-trimethylsilylhepta-4,5-dien-3-ol 73-76, but with a negligible degree of stereospecificity.
Buckle, Michael J.C.,Fleming, Ian,Gil, Salvador,Pang, Kah Ling Christine
p. 749 - 769
(2007/10/03)

Stereocontrol in organic synthesis using silicon-containing compounds. Studies directed towards the synthesis of ebelactone A
Several approaches to the synthesis of ebelactone A 2 are described, culminating in the synthesis of the benzenesulfonate of 2-epi-ebelactone A 161. All the approaches were based on three fragments A, B and C, originally defined in general terms in Scheme 1, but eventually used as the aldehyde 72, the allenylsilane 3 and the aldehyde 139, respectively. They were joined, first B with C, and then B+C with A. In the main routes to fragments A and C, the relative stereochemistry was controlled by highly stereoselective enolate methylations 66 → 67, 68 → 69, and 135 → 136, in each case anti to an adjacent silyl group, and by a highly stereoselective hydroboration of an allylsilane 137 → 138, also anti to the silyl group. The hydroxyl groups destined to be on C-3 and C-11 were unmasked by silyl-to-hydroxy conversions 69 → 70 and 138 → 139 with retention of configuration. The stereochemistry created in the coupling of fragment B to C was controlled by the stereospecifically anti SE2′ reaction between the enantiomerically enriched allenylsilane 3 and the aldehyde 139. The double bond geometry was controlled by syn stereospecific silylcupration 148 → 151, and preserved by iododesilylation 151 → 152 of the vinylsilane with retention of configuration, and Nozaki-Hiyama-Kishi coupling with the aldehyde 72 gave the whole carbon skeleton 153 of ebelactone A with the correct relative configuration, all of which had been controlled by organosilicon chemistry. In the steps to remove the superfluous allylic hydroxyl, an intermediate allyllithium species 156 abstracted the proton on C-2, and its reprotonation inverted the configuration at that atom. Other routes to the fragments A and C were also explored, both successful and unsuccessful, both silicon-based and conventional, and a number of unexpected side reactions were investigated.
Archibald, Sarah C.,Barden, David J.,Bazin, Jerome F.Y.,Fleming, Ian,Foster, Colin F.,Mandal, Ajay K.,Mandal, Amit K.,Parker, David,Takaki, Ken,Ware, Anne C.,Williams, Anne R.B.,Zwicky, Anna B.
p. 1051 - 1064
(2007/10/03)

Preparation of optically pure propargylic and allylic alcohols from 2-(trimethylsilyl)vinyl sulfoxides as a chiral ethynyl anion synthon: Computational studies on elimination reaction of 2-(trimethylsilyl)vinyl sulfoxides
The reaction of the (α-carbanion derived from (trimethylsilyl)vinyl sulfoxides with aldehydes afforded a diastereomeric mixture of the products. Each diastereomer was subjected to specific elimination reactions to give optically pure propargylic, trimethylsilylated propargylic, and allylic alcohols. Acceleration of the sulfenic acid-elimination from the β-silylvinyl sulfoxide was demonstrated by the ab initio calculation to be ascribed mainly to the β-effect of the silyl group.
Nakamura, Shuichi,Kusuda, Shinya,Kawamura, Kiyoshi,Toru, Takeshi
p. 640 - 647
(2007/10/03)

Separation of enantiomers by lipase-catalyzed fluorous-phase delabeling
Simultaneous enantiomer-selective fluorous-phase delabeling and kinetic resolution was achieved by lipase-catalyzed alcoholysis of highly fluorinated esters of racemic alcohols. The separation of the fast-reacting delabeled enantiomers and the slow-reacting fluorous-phase labeled enantiomers was performed very efficiently by partition in an organic/fluorous biphasic solvent system.
Swaleh, Sauda M,Hungerhoff, Benno,Sonnenschein, Helmut,Theil, Fritz
p. 4085 - 4089
(2007/10/03)

Silicon-tethered cyclocarbonylation of alkynes
(figure presented) Temporary union of alkynes in the Fe(CO)5-promoted cyclocarbonylation provides a method for carbonylative cross-coupling of alkynes to construct unsymmetrically substituted cyclopentadienones.
Pearson, Anthony J.,Kim, Jin Bum
p. 2837 - 2840
(2007/10/03)

Combining lipase-catalyzed enantiomer-selective acylation with fluorous phase labeling: A new method for the resolution of racemic alcohols
Lipase-catalyzed acylation of racemic alcohols with a highly fluorinated acyl donor allows their kinetic resolution accompanied by the simultaneous enantiomer-selective fluorous phase labeling. Both the tagged and the untagged enantiomer can be separated without chromatography by a very efficient partition between a fluorous and an organic phase. The method has been successfully applied to the resolution of typically racemic secondary alcohols of low molecular weight. The fluorous label can be recovered quantitatively.
Hungerhoff, Benno,Sonnenschein, Helmut,Theil, Fritz
p. 1781 - 1785
(2007/10/03)

Novel rearrangements of 4-silyl-3-buten-2-ones
Two-4-silyl-3-buten-2-ones, 2a, and 2c, underwent an interesting rearrangement involving migration of the allyl or phenyl group on the silicon atom to the adjacent enone carbon when treated with various bases.
Jung, Michael E.,Piizzi, Grazia
p. 3911 - 3914
(2007/10/03)

Allylsilane-modified amino acids from the Claisen rearrangement
The Claisen rearrangement of the N-protected, silylated allyl glycinates 11 and 12 led to the formation of allyl/silyl-functionalized amino acids 13 and 14 in yields up to 80%. The diastereoisomer ratio varied from 2:1 to 29:1 for 11mb, and from 2:1 to 46:1 (syn/anti) for 12mb, depending on reaction conditions, as shown by X-ray crystallographic analysis of 14mb. The relationship between the size of the alkyl groups on the chlorosilane reagent (Me2R″SiCl, R″ = Cl, Me, t-Bu, Ph) used as an enolate trap and the observed stereoselectivity was investigated in the case of the Ireland - Claisen variant. Me3SiCl gave the best results. However, the size of the alkyl groups on the silylated ester (Me2R″Si, R = Me, t-Bu, Ph, i-Pr) did not exert a significant effect on the diastereoselectivity or yield of the rearrangement.
Mohamed, Mustafa,Brook, Michael A.
p. 4165 - 4181
(2007/10/03)

Lipase-mediated resolution of 4-TMS-3-butyn-2-ol and use of the mesylate derivatives as a precursor to a highly stereoselective chiral allenylindium reagent
Matrix presented An improved procedure for the resolution of 4-trimethylsilyl-3-butyn-2-ol has been developed. The mesylate derivatives of the resolved alcohols have been found to undergo highly enantio-, regio-, and diastereoselective additions to aldehy
Marshall, James A.,Chobanian, Harry R.,Yanik, Mathew M.
p. 3369 - 3372
(2007/10/03)

Synthesis of stereopentad analogues of the C14-C22 segment of callystatin A through additions of chiral allenylzinc reagents to stereotriads
The addition of (P)- and (M)-allenylzinc reagents, prepared in situ through Pd-catalyzed metalation of(R)- and (S)-3-butyn-2-ol mesylates, to diastereomeric stereotriad aldehydes 8, 13, 18, and 23 of syn,syn, syn,anti, anti,anti, and anti,syn stereochemis
Marshall,Schaaf
p. 7825 - 7831
(2007/10/03)

Total synthesis of FR901464. Convergent assembly of chiral components prepared by asymmetric catalysis [17]
-
Thompson,Jamison,Jacobsen
p. 10482 - 10483
(2007/10/03)

Asymmetric transfer hydrogenation of α,β-acetylenic ketones
-
Matsumura, Kazuhiko,Hashiguchi, Shohei,Ikariya, Takao,Noyori, Ryoji
p. 8738 - 8739
(2007/10/03)

Synthesis of acetogenins
A method for the synthesis of bis-tetrahydrofuranyl annonaceous acetogenins, including the natural products and analogs thereof, is provided which proceeds by the Pd-mediated coupling of a bis-tetrahydrofuranyl-subunit comprising a terminal alkyne, with a
-
(2008/06/13)

Direct catalytic enantioselective reduction of achiral α,β-ynones. Strong remote steric effects across the C-C triple bond
-
Helal, Christopher J.,Magriotis, Plato A.,Corey
p. 10938 - 10939
(2007/10/03)

O→Csp Migration of the Trimethylsilyl Group in Alkynyl Trimethylsilyl Ethers
1,4- and 1,5-O→Csp-Migration of the trimethylsilyl group in Grignard derivatives of α- and β-acetylenic trimethylsilyl ethers, followed by hydrolysis, results in formation of trimethylsilylalkynyl alcohols. The reactivity of alkynyl trimethylsilyl ethers in the isomerization is determined by the structure of the substrate and reaction conditions (polarity of the medium and concentration of the reactants).
Novokshonov,Medvedeva,Demina,Sherstyannikova,Voronkov
p. 1770 - 1773
(2007/10/03)

Method for the synthesis of bis-tetrahydrofuranyl Annonaceous acetogenins
A method for the synthesis of bis-tetrahydrofuranyl Annonaceous acetogenins, including the natural products and analogs thereof, is provided which proceeds by the Pd-mediated coupling of a bis-tetrahydrofuranyl-subunit comprising a terminal alkyne, with a (C4)-hydroxybutenolide subunit comprising a terminal vinyl iodide, followed by selective reduction of the resulting enyne.
-
(2008/06/13)

A practical synthesis of chiral propargylic alcohols
A practical and efficient synthesis of chiral propargylic alcohols has been developed starting from inexpensive and readily available chiral methyl lactate. In addition, a regioselective desilylation method was discovered for oxygen deprotection of bis-silylated alkynols having a terminal trimethylsilyl group.
Ku, Yi-Yin
p. 2733 - 2736
(2007/10/02)

An Efficient and Versatile Synthesis of the Butenolide Subunit of 4-Hydroxylated Annonaceous Acetogenins
Title butenolides 2 have been synthesized by an efficient and versatile route that provides access to any stereoisomer by use of individual enantiomers of the precursors 3-butyn-2-ol and terminal epoxides.
Hoye, Thomas R.,Humpal, Paul E.,Jimenez, Jorge I.,Mayer, Michael J.,Tan, Lushi,Ye, Zhixiong
p. 7517 - 7520
(2007/10/02)

Convenient Preparation of Optically Pure Propargylic Alcohols Using 2-(Trimethylsilyl)vinyl Sulfoxide As A Novel Chiral Synthon
Both enentiomers of optically pure propargylic alcohols are conveniently prepared by the reaction of α-vinyl anion of 2-(trimethylsilyl)vinyl p-tolyl sulfoxide with aldehydes and subsequent either desilylsulfination or thermal elimination of the sulfinyl group.
Kusuda, Shinya,Kawamura, Kiyoshi,Ueno, Yoshio,Toru, Takeshi
p. 6587 - 6590
(2007/10/02)

Synthesis of Enantioenriched Homopropargylic Alcohols through Diastereoselective SE' Additions of Chiral Allenylstannanes to Aldehydes
Allenylstannanes (S)-4 and (R)-4, available in ca. 90percent ee from alkynones 1 through reduction with the LiAlH4-Darvon alcohol or -ent-Darvon alcohol complex, followed by SN2' displacement on the derived mesylates (R)-3 or (S)-3 with Bu3SnLi*CuBr*Me2S, readily add to various aldehydes under Lewis acid catalysis to afford optically active homopropargylic alcohols with good to excellent syn diastereoselectivity.With 2-(benzyloxy)propanal (48), MgBr2-catalyzed reactions are highly stereoselective, affording the syn adduct 49 from the (S)-stannane (S)-4 and the anti adduct 52 from the (R)-stannane (R)-4.BF3-promoted additions give mainly or exclusively the syn adducts 49 and 51.Additions of (S)- and (R)-4 to (R)-3-(benzyloxy)-2-methylpropanal (61) yield the syn adducts 62 and 64 as major or exclusive products.
Marshall, James A.,Wang, Xiao-jun
p. 1242 - 1252
(2007/10/02)

A Regioselective and Stereospecific Synthesis of Allylsilanes from Secondary Allylic Alcohol Derivatives
Primary and secondary allylic acetates and benzoates react with the dimethyl(phenyl)silyl-cuprate reagent to give allylsilanes, provided that the THF in which the cuprate is prepared is diluted with ether before addition of the allylic ester.The reaction is reasonably regioselective in some cases: (i) when the allylic system is more-substituted at one end than the other, as in the reactions 4->5 and 9->10; (ii) when the steric hindrance at one end is neopentyl-like, as in the reactions 15->16; and (iii) when the disubstituted double bond has the Z configuration, as in th e reactions Z-19->E-21 or, better, because the silyl group is becoming attached to the less-sterically hindered end of the allylic system, Z-20->E-22.The regioselectivity is better if a phenyl carbamate is used in place of the ester, and a three-step protocol assembling the mixed cuprate on the leaving group is used, as in the reactions 23->24 and E- or Z-29->E-21, or, best of all, because the silyl group is again becoming attached to the less-sterically hindered end of the allylic system, E- or Z-30->E-22.This sequence works well to move the silyl group onto the more substituted end of an allyl system, but only when the move is from a secondary allylic carbamate to a tertiary allylsilane, as in the reaction 38->39.Allyl(trimethyl)silanes can be made using alkyl- or aryl-cuprates on trimethylsilyl-containing allylic esters and carbamates, as in the reactions 40->41, and 43->44.The reaction of the silyl-cuprate with allylic esters and the three-step sequence with the allylic carbamates are stereochemically complementary, the former being stereospecifically anti and the latter stereospecifically syn.Homochiral allylsilanes can be ma de by these methods with high levels of stereospecificity, as shown by the synthesis of the allylsilanes 54, 58 and 59.
Fleming, Ian,Higgins, Dick,Lawrence, Nicholas J.,Thomas, Andrew P.
p. 3331 - 3350
(2007/10/02)

Enantioselective esterifications of unsaturated alcohols mediated by a lipase prepared from Pseudomonas sp.
Competition experiments and measurements of enantioselectivities were used to develop a simple active-site model (Figure 1) for resolutions of β-hydroxy-α-methylene carbonyl compounds III via acyl transfers mediated by lipase from Pseudomonas sp. (AK). Further experiments were used to test and refine this model with respect to resolutions of allylic, propargylic, homopropargylic, and other alcohols (Tables I-IV, respectively). The model proved extremely reliable for predicting the sense of the asymmetric induction, and the combined data collected in this paper give an indication of what structural features of the substrates can be correlated with high enantioselectivities in these resolutions. Furthermore, the results account for the conspicuous reversal of enantioselectivity previously observed in resolutions of γ-hydroxy-α,β-unsaturated esters 35. Kinetic resolutions of two substrates (allenol 14 and dienol 9) via asymmetric epoxidations were performed for comparison with the methodology presented in this paper.
Burgess, Kevin,Jennings, Lee D.
p. 6129 - 6139
(2007/10/02)

Kinetic Resolution of Chiral Unsaturated Alcohols That Cannot Be Resolved Efficently via Enantioselective Epoxidation
-
Burgess, Kevin,Jennings, Lee D.
p. 7434 - 7435
(2007/10/02)

Optically active compounds and process for producing thereof
The present invention provides optically active compounds and a process for producing the optically active compounds by a biochemical method in which specific compounds having hydroxyl or acyloxy groups are reacted with esters in the presence of hydrolase. The compounds have the following general formula: STR1 wherein R1, R2 and R3 are selected from alkyl groups having 1-4 carbon atoms and phenyl groups, X is selected from a hydrogen atom and STR2 R is selected from alkyl groups having 1-20 carbon atoms, and C* indicates an asymmetric carbon atom.
-
(2008/06/13)

EPOXY-SILANES IN ORGANIC SYNTHESIS
Stereoselective reactions involving functionalised β,γ-epoxysilanes and epoxide-allylsilanes provide a range of synthetically useful transformations.
Procter, Garry,Russell, Andrew T.,Murphy, Patrick J.,Tan, T.S.,Mather, Andrew N.
p. 3953 - 3974
(2007/10/02)

Synthesis of Allenylsilanes from Propargyl Carbamates
Pent-3-yn-2-yl acetate (1) reacts with dimethyl(phenyl)silyl cuprate reagent to give a mixture of allenylsilane and propargylsilane.The corresponding N-phenylcarbamate (4) gives only the allenylsilane.Four other examples of this regioselective reaction are reported.The stereochemistry is largely syn.
Fleming, Ian,Takaki, Ken,Thomas, Andrew P.
p. 2269 - 2274
(2007/10/02)

ALLYLSILANES IN ORGANIC SYNTHESIS; STEREOSELECTIVE HYDROXYLACTONISATION OF CHIRAL AMIDE-ALLYLSILANES
The amide-allylsilanes (1) and (10) undergo stereoselective hydroxylactonisation on treatment with m-CPBA; the major products from (1) and (10) were converted into parasorbic acid (9) and the carpenter bee pheromone (13) respectively.
Russell, Andrew T.,Procter, Garry
p. 2041 - 2044
(2007/10/02)

Chemical Properties

Boiling Point: 170.2 °C at 760 mmHg
Flash Point:56.8 °C
Density: 0.883 g/cm³
Solubility:highly soluble in all standard organic solvents (hexanes, toluene, CH2Cl2, EtOAc, alcohols, ethers). Partially soluble in water.
Storage Temp.:2-8°C
Vapor Pressure: 0.477mmHg at 25°C
Refractive Index: n 20/D 1.446
PKA: 13.78±0.20(Predicted)
BRN: 1923632
PSA: 20.23000
LogP: 1.24800

Global suppliers and manufacturers of 6999-19-5total 27 suppliers on LookChem

Company Name
Business Type
Min Order
FOB Price
Main Products
Contact

Dayang Chem (Hangzhou) Co.,Ltd.
Business Type:Lab/Research institutions
Min Order:1 Kilogram
FOB Price:USD $ 3.0-3.0 / Kilogram
Main Products:994
Country:

Zhuozhou Wenxi import and Export Co., Ltd
Business Type:Trading Company
Min Order:1 Kilogram
FOB Price:USD $ 139.0-210.0 / Kilogram
Main Products:1
Country:

Ality Chemical Corporation
Business Type:Other
Min Order:No Data
FOB Price:No Data
Main Products:165
Country:

Hangzhou J&H Chemical Co., Ltd.
Business Type:Lab/Research institutions
Min Order:No Data
FOB Price:No Data
Main Products:46
Country:

Zibo Hangyu Biotechnology Development Co., Ltd
Business Type:Lab/Research institutions
Min Order:10 Gram
FOB Price:USD $ 100.0-100.0 / Gram
Main Products:3496
Country:

Shanghai Minstar Chemical Co., Ltd
Business Type:Lab/Research institutions
Min Order:100 Gram
FOB Price:No Data
Main Products:120
Country:

GIHI CHEMICALS CO.,LIMITED
Business Type:Lab/Research institutions
Min Order:No Data
FOB Price:No Data
Main Products:80
Country:

Kunshan Push Trading Co.,LTD
Business Type:Lab/Research institutions
Min Order:No Data
FOB Price:No Data
Main Products:25
Country:

Henan Allgreen Chemical Co.,Ltd
Business Type:Manufacturers
Min Order:No Data
FOB Price:No Data
Main Products:34
Country:

Wuxi TAA Chemical Industry Co.,LTD.
Business Type:Other
Min Order:No Data
FOB Price:No Data
Main Products:105
Country:

Chemsigma International Co.,Ltd.
Business Type:Lab/Research institutions
Min Order:No Data
FOB Price:No Data
Main Products:84
Country:

Antimex Chemical Limied
Business Type:Lab/Research institutions
Min Order:No Data
FOB Price:No Data
Main Products:163
Country:

HANGZHOU TIANYE CHEMICALS CO., LTD.
Business Type:Trading Company
Min Order:No Data
FOB Price:No Data
Main Products:73
Country:

Hangzhou Sartort Biopharma Co., Ltd
Business Type:Lab/Research institutions
Min Order:No Data
FOB Price:No Data
Main Products:80
Country:

Hangzhou Fandachem Co.,Ltd
Business Type:Other
Min Order:No Data
FOB Price:No Data
Main Products:52
Country:

ZHEJIANG JIUZHOU CHEM CO.,LTD
Business Type:Trading Company
Min Order:No Data
FOB Price:No Data
Main Products:26
Country:

HENAN SUNLAKE ENTERPRISE CORPORATION
Business Type:Trading Company
Min Order:10 Gram
FOB Price:No Data
Main Products:1
Country:

Zhengzhou Kingorgchem Chemical Technology Co., Ltd.
Business Type:Lab/Research institutions
Min Order:No Data
FOB Price:No Data
Main Products:1
Country:

ENAO Chemical Co, Limited
Business Type:Lab/Research institutions
Min Order:No Data
FOB Price:No Data
Main Products:1
Country:

Yinghao Pharm Co.,Ltd.
Business Type:Lab/Research institutions
Min Order:No Data
FOB Price:No Data
Main Products:1
Country:

Post a RFQ

Cas No.:

Product Name:

Quantity:

Email:

Company name:

Valid Period:

Detailed Requirements:

Enter 15 to 2000 letters.Word count: 0 letters

Attach files(File Format: Jpeg, Jpg, Gif, Png, PDF, PPT, Zip, Rar,Word or Excel Maximum File Size: 3MB)

What can I do for you?
Get Best Price

Get Best Price for 6999-19-5

Article Database

6999-19-5

Articles about 6999-19-5Total 56 be found

More Articles about upstream products of 6999-19-5

More Articles about downstream products of 6999-19-5

Chemical Properties

Boiling Point: 170.2 °C at 760 mmHg

Flash Point:56.8 °C

Density: 0.883 g/cm³

Solubility:highly soluble in all standard organic solvents (hexanes, toluene, CH2Cl2, EtOAc, alcohols, ethers). Partially soluble in water.

Storage Temp.:2-8°C

Vapor Pressure: 0.477mmHg at 25°C

Refractive Index: n 20/D 1.446

PKA: 13.78±0.20(Predicted)

BRN: 1923632

PSA: 20.23000

LogP: 1.24800

Global suppliers and manufacturers of 6999-19-5total 27 suppliers on LookChem

Article Database

6999-19-5

Articles about 6999-19-5Total 56 be found

More Articles about upstream products of 6999-19-5

More Articles about downstream products of 6999-19-5

Chemical Properties

Boiling Point: 170.2 °C at 760 mmHg

Flash Point:56.8 °C

Density: 0.883 g/cm3

Solubility:highly soluble in all standard organic solvents (hexanes, toluene, CH2Cl2, EtOAc, alcohols, ethers). Partially soluble in water.

Storage Temp.:2-8°C

Vapor Pressure: 0.477mmHg at 25°C

Refractive Index: n 20/D 1.446

PKA: 13.78±0.20(Predicted)

BRN: 1923632

PSA: 20.23000

LogP: 1.24800

Global suppliers and manufacturers of 6999-19-5total 27 suppliers on LookChem

Density: 0.883 g/cm³