- Ring-closing metathesis approaches towards the total synthesis of rhizoxins
-
Efforts are described towards the total synthesis of the bacterial macrolide rhizoxin F, which is a potent tubulin assembly and cancer cell growth inhibitor. A significant amount of work was expanded on the construction of the rhizoxin core macrocycle by ring-closing olefin metathesis (RCM) between C(9) and C(10), either directly or by using relay substrates, but in no case was ringclosure achieved. Macrocycle formation was possible by ring-closing alkyne metathesis (RCAM) at the C(9)/C(10) site. The requisite diyne was obtained from advanced intermediates that had been prepared as part of the synthesis of the RCM substrates. While the direct conversion of the triple bond formed in the ring-closing step into the C(9)-C(10) E double bond of the rhizoxin macrocycle proved to be elusive, the corresponding Z isomer was accessible with high selectivity by reductive decomplexation of the biscobalt hexacarbonyl complex of the triple bond with ethylpiperidinium hypophosphite. Radical-induced double bond isomerization, full elaboration of the C(15) side chain, and directed epoxidation of the C(11)-C(12) double bond completed the total synthesis of rhizoxin F.
- Altmann, Karl-Heinz,Liniger, Marc,Neuhaus, Christian M.
-
-
- Controlled Reduction of Nitriles by Sodium Hydride and Zinc Chloride
-
A new protocol for the controlled reduction of nitriles to aldehydes was developed using a combination of sodium hydride and zinc chloride. The iminyl zinc intermediates derived from aromatic nitriles could be further functionalized with allylmetal nucleophiles to afford homoallylamines. As the method allows the reduction of various aliphatic and aromatic nitriles with a concise procedure under milder reaction conditions and exhibits wide functional group compatibility, it is well suited for use in various opportunities in chemical synthesis.
- Chiba, Shunsuke,Ong, Derek Yiren
-
p. 1369 - 1378
(2020/04/27)
-
- SUBSTITUTED HETEROARYL COMPOUNDS AND METHODS OF USE
-
The present invention provides novel heteroaryl compounds, pharmaceutical acceptable salts and formulations thereof. They are useful in preventing, managing, treating or lessening the severity of a protein kinase-mediated disease. The invention also provides pharmaceutically acceptable compositions comprising such compounds and methods of using the compositions in the treatment of protein kinase-mediated disease.
- -
-
Paragraph 0492
(2017/04/14)
-
- Substituted heteroaryl compound and composition thereof, and uses of substituted heteroaryl compound and composition thereof
-
The present invention provides a substituted heteroaryl compound and a composition thereof, and uses of the substituted heteroaryl compound and the composition, wherein the compound is a compound represented by a formula (I) or a stereoisomer, a tautomer, a nitrogen oxide, a solvate, a metabolite, a pharmaceutically acceptable salt or a prodrug of the compound represented by the formula (I). The present invention further provides a pharmaceutical composition containing the compound, wherein the pharmaceutical composition can regulate activity of protein kinases, particularly Aurora kinases and JAK kinases, and can be used for prevention, treatment, therapy and alleviation of protein kinases, particularly Aurora kinases and JAK kinase activity mediated diseases or disorders.
- -
-
Paragraph 1175; 1176; 1177; 1178
(2017/04/29)
-
- Total synthesis of haliclamide
-
A stereoselective approach for the synthesis of haliclamide 1, a marine natural product, has been developed. The notable features of our synthesis include MacMillan cross aldol, Mitsunobu inversion, Yamaguchi-Hirao alkylation, Steglich esterification and
- Gahalawat, Suraksha,Pandey, Satyendra Kumar
-
p. 9287 - 9293
(2016/10/13)
-
- Biocatalytic Approach for the Total Synthesis of (-)-Malyngolide and Its C(5)-Epimer
-
An enzymatic approach has been successfully utilized in the total synthesis of (-)-malyngolide and its C(5)-epimer. The required configuration was established by an enzymatic kinetic resolution and Sharpless asymmetric dihydroxylation.
- Srivastava, Nikhil,Subba Reddy, Basi V.
-
p. 267 - 272
(2016/05/02)
-
- Total synthesis of odoamide, a novel cyclic depsipeptide, from an Okinawan marine cyanobacterium
-
Odoamide is a novel cyclic depsipeptide with highly potent cytotoxic activity isolated from the Okinawan marine cyanobacterium Okeania sp. It contains a 26-membered macrocycle composed of a fatty acid moiety, a peptide segment and isoleucic acid. Four pos
- Kaneda, Masato,Sueyoshi, Kosuke,Teruya, Toshiaki,Ohno, Hiroaki,Fujii, Nobutaka,Oishi, Shinya
-
p. 9093 - 9104
(2016/10/07)
-
- DIHYDROPYRONE COMPOUNDS AND HERBICIDES COMPRISING THE SAME
-
The present invention provides a compound having an excellent efficacy for controlling weeds. A dihydropyrone compound of formula (I): wherein m is 1, 2 or 3; n is an integer of any one of 1 to 5; X represents O, S, S(O) or S(O)2; R1 /sup
- -
-
Paragraph 0089
(2014/06/23)
-
- Palladium on charcoal as a catalyst for stoichiometric chemo- and stereoselective hydrosilylations and hydrogenations with triethylsilane
-
Stoichiometric quantities of triethylsilane in the presence of activated Pd/C as the catalyst can be used to effect chemo-, regio-, and stereoselective hydrosilylation and transfer hydrogenation reactions. α,β-Unsaturated aldehydes and ketones are selectively hydrosilylated to give the corresponding enol silanes or transfer hydrogenated to give the saturated carbonyl compounds in the presence of other reducible functional groups.
- Tuokko, Sakari,Pihko, Petri M.
-
p. 1740 - 1751
(2015/02/19)
-
- Synthesis of a C1-C11 fragment of Zincophorin using planar chiral, neutral π-allyl iron complexes
-
A key step in the synthesis of a C1-C11 fragment of the ionophore antibiotic Zincophorin involves the addition of an α-alkoxyalkylcopper(i) reagent to a planar chiral, neutral π-allyl iron complex. The key allylic alkylation reaction is highly regio- and
- Cooksey, John P.
-
p. 5117 - 5126
(2013/08/23)
-
- COMPOUNDS FOR THE TREATMENT OF METABOLIC DISORDERS
-
The present invention is directed to therapeutic compotmds of the following formula (I) which have activity as agonists of GPR 119 and are useful for the treatment of metabolic disorders including type II diabetes.
- -
-
Page/Page column 28
(2010/10/03)
-
- Solvent-free olefin hydroformylation using hemispherical diphosphites
-
With rhodium complexes containing hemispherical diphosphite ligands derived from a calixarene skeleton, olefins can be hydroformylated efficiently under solvent-free conditions. For example, in the hydroformylation of 1-octene (T = 80 °C, P = 20 bar, olefin:Rh = 200 000:1) one of the catalysts investigated resulted in a TOP of 17290 mol (converted 1-octene)mol(Rh)-1h -1, the regioselectivity towards the linear aldehyde reaching then 97.9%.
- Monnereau, Laure,Semeril, David,Matt, Dominique
-
experimental part
p. 3068 - 3073
(2010/08/07)
-
- Process for total synthesis of pladienolide B and pladienolide D
-
[Problems to be Solved] To provide an effective process for total synthesis of pladienolide B and pladienolide D having excellent anti-tumor activity and to provide useful intermediates in the above-described process. [Measure for Solving the Problem] A process for producing a compound represented by Formula (11): wherein P1, P7, P8, P9 and R1 are the same as defined below, characterized by including reacting a compound represented by Formula (12): wherein P7 means a hydrogen atom or a protecting group for hydroxy group; R1 means a hydrogen atom or a hydroxy group, with a compound represented by Formula (13): wherein P1 means a hydrogen atom or a protecting group for hydroxy group; P8 means a hydrogen atom, an acetyl group or a protecting group for hydroxy group; P9 means a hydrogen atom or a protecting group for hydroxy group; or P8 and P9 may form together a group represented by a formula: wherein R5 means a phenyl group which may have a substituent, in the presence of a catalyst.
- -
-
Page/Page column 33-34
(2010/11/29)
-
- Highly regioselective hydroformylation with hemispherical chelators
-
The hemispherical diphosphites (R,R)- or (S,S)-5,11,17,23-tetratert-butyl- 25,27-di(OR)-26,28-bis(1,1′-binaphthyl-2,2′-dioxyphosphanyloxy) -calix[4]arene (R = OPr, OCH2Ph, OCH2-naphtyl, O-fluorenyl; R = H, R' = OPr) (LR), all with C2 symmetry, have been synthesised starting from the appropriate di-O-alkylated calix[4]-arene precursor. In the presence of [Rh(acac)(CO)2], these ligands straightforwardly provide chelate complexes in which the metal centre sits in a molecular pocket defined by two naphthyl planes related by the C 2 axis and the two apically situated R groups. Hydroformylation of octene with the LPr/Rh system turned out to be highly regioselective, the linear-to-branched (l:b) aldehyde ratio reaching 58:1. The l:b ratio significantly increased when the propyl groups were replaced by -CH 2Ph (l:b = 80) or -CH2naphthyl (1:b = 100) groups, that is, with substituents able to sterically interact with the apical metal sites, but without inducing an opening of the cleft nesting the catalytic centre. The trend to preferentially form the aldehyde the shape of which fits with the shape of the catalytic pocket was further confirmed in the hydroformylation of styrene, for which, in contrast to catalysis with conventional diphosphanes, the linear aldehyde was the major product (up to ca. 75 % linear aldehyde). In the hydroformylation of frarts-2-octene with the Lbenzyl/ Rh system, combined isomerisation/hydroformylation led to a remarkably high 1:b aldehyde ratios of 25, thus showing that isomerisation is more effective than hydroformylation. Unusually large amounts of linear products were also observed with all the above diphosphites in the tandem hydroformylation/amination of styrene (1:b of ca. 3:1) as well as in the hydroformylation of allyl benzyl ether (1:b ratio up to 20).
- Semeril, David,Matt, Dominique,Toupet, Loic
-
experimental part
p. 7144 - 7155
(2009/08/07)
-
- Total synthesis of epothilones B and D: Stannane equivalents for β-keto ester dianions
-
(Chemical Equation Presented) Studies leading to a total synthesis of epothilones B and D are described. The overall synthetic plan was based on late-stage fragment assembly of two segments representing C1-C 9 and C10-C21 of the structure. The C 1-C9 fragment was prepared by elaboration of commercially available (2R)-3-hydroxy-2-methylpropanoate at both ends of the three-carbon unit. Introduction of carbons 1-4 containing the gem-dimethyl unit was achieved in a convergent manner using a diastereoselective addition of a stannane equivalent of a β-keto ester dianion. An enantioselective addition of such a stannane equivalent for a β-keto ester dianion was also used to fashion one version of the C10-C21 subunit; however, the fragment assembly (using bimolecular esterification followed by ring-closing metathesis) with this subunit failed. Therefore, fragment assembly was achieved using a Wittig reaction; this was followed by macrolactonization to close the macrocycle. The C10-C21 subunit needed for this approach was prepared in an efficient manner using the Corey-Kim reaction as a key element. Other key reactions in the synthesis include a stereoselective SmI 2 reduction of a β-hydroxy ketone and a critical opening of a valerolactone with aniline which required extensive investigation.
- Keck, Gary E.,Giles, Robert L.,Cee, Victor J.,Wager, Carrie A.,Yu, Tao,Kraft, Matthew B.
-
supporting information; experimental part
p. 9675 - 9691
(2009/04/07)
-
- PIPERIDINES AND RELATED COMPOUNDS FOR TREATMENT OF ALZHEIMER’S DISEASE
-
Compounds of formula (I) are modulators of gamma-secretase, and hence are useful in treatment of Alzheimer’s disease.
- -
-
Page/Page column 43
(2008/06/13)
-
- Synthesis of the C15-C23 fragment of dictyostatin using a highly stereoselective Carreira alkynylation
-
A straightforward synthesis of the C15-C23 fragment of dictyostatin has been achieved by a highly stereoselective Carreira alkynylation between alkyne 1 and aldehyde 2, followed by three chemoselective reductions.
- Sharon, Ofer,Monti, Chiara,Gennari, Cesare
-
p. 5873 - 5878
(2008/02/02)
-
- Total synthesis of the potent antitumor macrolides pladienolide B and D
-
Getting cross: The total syntheses of two pladienolides (see picture), which have prominent antitumor activity based on a unique mechanism of action, have been accomplished, and their absolute configurations were verified. The 12-membered aliphatic macrolide structure was formed by ring-closing metathesis, and the side-chain moiety was coupled to the macrolide by Julia-Kocienski olefination or cross-metathesis. (Chemical Equation Presented).
- Kanada, Regina M.,Itoh, Daisuke,Nagai, Mitsuo,Niijima, Jun,Asai, Naoki,Mizui, Yoshiharu,Abe, Shinya,Kotake, Yoshihiko
-
p. 4350 - 4355
(2008/03/12)
-
- Studies directed towards the synthesis of antascomicin A: stereoselective synthesis of the C22-C34 fragment of the molecule
-
A stereoselective synthesis of the C22-C34 fragment of the non-immunosuppressive immunophilin-binding natural product, antascomicin A was achieved using d-quinic acid as the starting material and highly stereoselective aldol reactions were employed, as ke
- Chakraborty, Tushar Kanti,Mohan, Bajjuri Krishna,Sreekanth, Midde
-
p. 5003 - 5005
(2007/10/03)
-
- MACROCYCLIC COMPOUNDS USEFUL AS PHARMACEUTICALS
-
The present invention provides compounds having formula (I), and additionally provides methods for the synthesis thereof and methods for the use thereof in the treatment of various disorders including inflammatory or autoimmune disorders, and disorders involving malignancy or increased angiogenesis, wherein R1 -R11, t, X, Y, Z, and n are as defined herein.
- -
-
Page/Page column 201
(2010/02/07)
-
- Convergent enantioselective synthesis of vinigrol, an architecturally novel diterpenoid with potent platelet aggregation inhibitory and antihypertensive properties. 1. Application of anionic sigmatropy to construction of the octalin substructure
-
The coupling of building blocks 15 and 36e in the presence of MgBr2·OEt2 at 0 °C proceeds with an exo stereoselectivity (3.2:1) considerably more advantageous for the acquisition of carbinol 37e than in the absence of the additive (exo/endo = 1:5.7). The pivotal transformation that sets all of the relevant stereocenters of the cis-octalin 55 is the oxyanionic-accelerated [3,3]-sigmatropic rearrangement of 37e. A salient feature is the structurally enforced adoption of a boatlike transition state that serves to properly set four vicinal methine hydrogens in an all-cis arrangement. The ensuing conversion of 55 into iodo sulfone 62 has permitted X-ray crystallographic confirmation of all absolute stereochemical assignments since the isopropyl substituent was initially installed enantioselectively via the Evans oxazolidinone protocol. No intramolecular anionic cyclization of 62 to generate the tricyclic framework was seen. This absence of reactivity is attributed to conformational factors that inhibit attainment of the proper SN2 reaction trajectory.
- Paquette, Leo A.,Guevel, Ronan,Sakamoto, Shuichi,Kim In Ho,Crawford, Jason
-
p. 6096 - 6107
(2007/10/03)
-
- Chemoenzymatic Approach toward the Pure Enantiomers of 2-Methyl-1,3-propanediol Mono(p-Methoxybenzyl Ether)
-
In a route towards the enantiomerically pure 2-methylpropane-1,3-diol mono(p-methoxybenzyl ether), which is an important starting material for natural product synthesis, a kinetic resolution approach by means of lipase-catalyzed hydrolysis as well as acyl
- Akeboshi, Tomohiro,Ohtsuka, Yoshikazu,Ishihara, Takashi,Sugai, Takeshi
-
p. 624 - 637
(2007/10/03)
-
- A convergent synthesis of (S)-β-methyl-2-aryltryptamine based gonadotropin releasing hormone antagonists
-
A practical synthesis of (S)-β-methyl-2-aryltryptamine based gonadotropin releasing hormone antagonists which features a palladium-catalyzed Larock indole synthesis and a palladium-catalyzed Suzuki-Miyaura sequence to install the 2-position aryl substitue
- Walsh, Thomas F,Toupence, Richard B,Ujjainwalla, Feroze,Young, Jonathan R,Goulet, Mark T
-
p. 5233 - 5241
(2007/10/03)
-
- Palladium(II)-catalyzed oxidation of alcohols to aldehydes and ketones by molecular oxygen
-
A novel combination of Pd(OAc)2/pyridine/MS3A catalyzes the aerobic oxidation in toluene of a variety of primary and secondary alcohols into the corresponding aldehydes and ketones in high yields. Various substituents and protecting groups are compatible with this oxidation. The ca. 2:3 ratio of O2 uptake to product yield is observed, whereas in the absence of MS3A, the ratio is ca. 1:1, suggesting the in situ formation of H2O2 and its decomposition by MS3A into water and oxygen. A catalytic cycle including the formation of a Pd(II)-alcoholate followed by β-elimination of a Pd(II)H species and a carbonyl compound and then the formation of a Pd(II)OOH species is proposed.
- Nishimura, Takahiro,Onoue, Tomoaki,Ohe, Kouichi,Uemura, Sakae
-
p. 6750 - 6755
(2007/10/03)
-
- Synthetic studies toward ansatrienines: Application of the Evans- Tishchenko reaction to chiral enones
-
Practical syntheses of the C9-C14 sterotriade 5 and the C1-C8 polyene unit 6 in ansatrienine A (mycotriene) (1a), and other ansamycin antibiotics is described. A key step for controlling the configuration of the stereogenic center at C13 involves the stereoselective reduction of enone 10 using the Evans-Tishchenko reaction.
- Schoening, Kai-Uwe,Hayashi,Powell, Douglas R.,Kirschning, Andreas
-
p. 817 - 820
(2007/10/03)
-
- Constructing the side-chain of the polyketide herbicide herboxidiene: A protocol for the synthesis of enantiomerically enriched C-11 to C-19 fragments
-
The aldehyde 5, corresponding to the C-11 to C-19 fragment of the polyketide herbicide herboxidiene 1, has been prepared in enantio-enriched form.
- Banwell, Martin G.,Bui, Chinh T.,Hockless, David C. R.,Simpson, Gregory W.
-
p. 1261 - 1263
(2007/10/03)
-
- Synthetic studies toward potent cytotoxic agent amphidinolide B : Synthesis of the entire C14-C26 moiety of the top half
-
Regioselective hydroboration of a 4-methyl-2-alkene, oxidation of the resulting mixture of isomeric alcohols, and finally diastereoselective reduction of the ketone are the key steps in the stereoselective synthesis of C19-C26 fragment of amphidinolide B
- Chakraborty, Tushar K.,Thippeswamy, Devasamudram,Suresh, Vayalakkada R.,Jayaprakash, Sarva
-
p. 563 - 564
(2007/10/03)
-
- The synthesis of the C-9 to C-21 sector of discodermolide: An efficient route to the C13-14 Z-trisubstituted alkene
-
The synthesis of the C-9 to C-21 sector of the immunosuppressive marine natural product discodermolide is described. The C-9 to C-15 subunit is synthesized in five steps from aldehyde 5 using the diene aldehyde cyclocondensation reaction. Diastereoselective alkylation of the previously synthesized C-16 to C-21 subunit by a suitably functionalized C-9 to C-15 synthon (3) leads to the C-9 to C-21 sector of discodermolide.
- Yang, Ge,Myles, David C.
-
p. 2503 - 2504
(2007/10/02)
-
- An Alkylative Strategy to the C-13 to C-21 Sector of Discodermolide
-
An approach to the C-13 to C-21 sector if the immunosuppressive marine natural product discodermolide (1) is described.The C-15 to C-16 bond is formed by diastereoselective alkylation of a ketone enolate.Either diastereomer of alkylation can be obtained by selecting the appropriate counter ion.The C-16 to C-21 subunit is prepared in two steps from 11.
- Yang, Ge,Myles, David C.
-
p. 1313 - 1316
(2007/10/02)
-
- 1,5-Asymmetric Induction in Lewis Acid-promoted Reactions of (5-Alkoxy-2,4-dimethylpent-2-enyl)tributylstannanes and Aldehydes
-
Allyltin trihalides generated in situ from (5-alkoxy-2,4-dimethylpent-2-enyl)tributylstannanes 8-10 and tin(IV) halides react with aldehydes with excellent 1,5-stereocontrol.
- Teerawutgulrag, Aphiwat,Thomas, Eric J.
-
p. 2863 - 2864
(2007/10/02)
-
- Super-acid Catalysed Addition of Allylsilanes to Carbonyl Compounds; Synthetic and Mechanistic Aspects
-
The addition of allyltrimethylsilane 8 to a variety of aldehydes and one ketone (cyclohexanone) was found to be induced by the super-acid TfOH2(1+)B(OTf)4(1-) (Tf = CF3SO2).In contrast to the analogous Lewis acid catalysed reaction, only catalytic amounts
- Davis, Anthony P.,Jaspars, Marcel
-
p. 2111 - 2118
(2007/10/02)
-
- An asymmetric synthesis of (+)-phyllanthocin
-
An enantiocontrolled synthesis of (+)-phyllanthocin from methyl R-3-hydroxylisobutyrate and the acrylic ester of D-pantolactone is accomplished in 20 steps in 5% overall yield.
- Trost,Kondo
-
p. 1613 - 1616
(2007/10/02)
-
- NOREPHEDRINE DERIVED 2-METHOXY OXAZOLIDINES AS CHIRAL FORMYL CATION EQUIVALENTS
-
Lewis acid catalyzed reaction of silylenolethers with 1 followed by a straightforward nondestructive removal of the chiral auxiliary affords the corresponding aldehydes in good e.e.Compound 1 respresents the first effective synthetic equivalent of formyl cation.
- Bernardi, Anna,Cardani, Silvia,Carugo, Oliviero,Colombo, Lino,Scolastico, Carlo,Villa, Roberto
-
p. 2779 - 2782
(2007/10/02)
-
- Chelation-Controlled Enantioselective Synthesis of Key Intermediates for the Preparation of Carbapenem Antibiotics PS-5 and 1β-Methyl-PS-5
-
Reaction of the E silyl ketene acetal derived from (1S,2R)-N-methylephedrine butyrate (7) with TiCl4 and β-alkoxy aldehyde 5 gave the aldol product in 75percent yield as a 78:11:11 mixture of stereoisomers.In agreement with a chelated transition structure
- Gennari, Cesare,Cozzi, Pier Giorgio
-
p. 4015 - 4021
(2007/10/02)
-
- Stereochemistry of SN2' Additions to Acyclic Vinyloxiranes
-
The isomeric trans-(E)-, trans-(Z)-, cis-(E)-, and cis-(Z)-vinyloxiranes 7,9,17 and 19 were prepared from 2-(benzyloxy)ethanol by sequential Swern-Wittig or Swern-Horner-Emmons propionate condensation, DIBAH reduction, Sharpless epoxidation, Swern oxidation, Wittig or Horner-Emmons acetate condensation, and a second DIBAH reduction.Addition of lithium dimethylcuprate and lithium methylcyanocuprate to these epoxides in THF-eather at -20 to 0 deg C afforded the allylic alcohols 22,25, ent-23, and ent-22 as the major products.These products are formed by anti addition to the lower energy conformer (s-trans for 7,17, and 19 and s-cis for 9) of the respective vinyloxirane.The conformational preferences of transition-state-like geometries of the vinyl-oxiranes, calculated with the aid of Still's MACROMODEL program, were in agreement with the observed trends.
- Marshall, James A.,Trometer, Joseph D.,Blough, Bruce E.,Crute, Thomas D.
-
p. 4274 - 4282
(2007/10/02)
-
- ALDOL CONDENSATIONS OF CHIRAL ETHYLKETONES: CONTROL BY CHIRAL BORON REAGENTS.
-
The chiral reagents (+)- and (-)-(Ipc)2BOTf, in the presence of Et3N, are used to control the aldol condensation reactions of chiral ethylketone 5 with prochiral aldehydes.The SS isomer, 6 or 8, or SA isomer, 7 or 9, is then formed in >99 percentee and wi
- Paterson, Ian,Lister, Anne M.
-
p. 585 - 588
(2007/10/02)
-
- Electrochemical Oxidation of (S)-Malic-Acid Derivatives: a Route to Enantiomerically Pure Alkylmalonaldehydic Esters
-
The 3,3-dialkylmalic-acid diesters, prepared by the previously described diastereoselective alkylations through dilithium alkoxide enolates, are saponified to the monoesters containing a free α-hydroxycarboxylic-acid moiety.The monoesters are subjected to electrochemical oxidative decarboxylation in MeOH.If the intermediate monoacids are purified, the malonaldehydic esters (2-formyl-2-alkoxycarboxylates) obtained by this procedure are enantiomerically pure; they have the same structural features, i.e. two enantiotopic functionalized branches on the (persubstituted) stereogenic center, as the well known 3-hydroxy-2-methylpropanoic acid ('Roche acid') which was employed frequently as a starting material for the preparation of either enantiomer of various target molecules.
- Renaud, Philippe,Muerzeler, Marianne,Seebach, Dieter
-
p. 292 - 298
(2007/10/02)
-
- Neighboring Group Participation by Oxygen in the Solvolysis of Acyclic γ-Alkoxy Substituted p-Toluenesulfonates
-
Methanolysis of branched 3-(benzyloxy)propyl p-toluenesulfonates, PhCH2OCR1R2CR3R4CHR5OTs (R1 = Me, R2-R5 = H; R1 = R2 = Me, R3-R
- Eliel, Ernest L.,Clawson, Leigh,Knox, David E.
-
p. 2707 - 2711
(2007/10/02)
-
- STEREOSELECTIVE ALDOL REACTIONS USING TiCl4 AS STEREOCHEMICAL TEMPLATE
-
TiCl4 mediated aldol condensations establish multiple contiguous chiral centers in an almost complete enantio- and diastereoselective way.
- Gennari, Cesare,Bernardi, Anna,Scolastico,Carlo,Potenza, Donatella
-
p. 4129 - 4132
(2007/10/02)
-
- Acyclic Stereoselection. 22. Diastereofacial Selectivity in the Lewis Acid Mediated Reactions of Allylsilanes with Chiral Aldehydes and Enones
-
The Lewis acid mediated reactions of chiral aldehydes 1-4 and enones 5-8 with allylsilanes 9 and 10 have been investigated.With aldehyde 1 and enones 5-7, modest diastereofacial preferences are seen, in the sense predicted by application of Felkin's model for asymmetric induction.Aldehydes 2-4 and enone 8 appear to react by way of chelated intermediates.With these four compounds, the diastereofacial preferences are rather large and are in the sense that is consistend with attack of the allylsilane on the least hindered face of the chelated intermediate.In the reaction of the trans and cis enones 6 and 8 with allyltrimethylsilane, a dramatic reversal of diastereofacial preference is observed; enone 6 gives a 84:14 ratio of products, while enone 8 provides a 10:90 mixture of the same products.
- Heathcock, Clayton H.,Kiyooka, Syun-ichi,Blumenkopf, Todd A.
-
p. 4214 - 4223
(2007/10/02)
-
- STUDIES IN MACROLIDE SYNTHESIS: AN EFFICIENT SYNTHESIS OF TWO CHIRAL FRAGMENTS OF ERYTHRONOLIDE A
-
An efficient asymmetric synthesis of the C1-C5 fragment (3) together with the epimeric C7-C11 fragment (4) used in the Stork approach to the synthesis of erythronolide A is described.
- Paterson, Ian,Patel, Shailesh K.,Porter, John R.
-
p. 3395 - 3396
(2007/10/02)
-
- REGIOSELECTIVITY OF THE REACTIONS OF TRIALKYLALUMINUM REAGENTS WITH 2,3-EPOXYALCOHOLS: APPLICATION TO THE SYNTHESIS OF α-CHIRAL ALDEHYDES
-
Treatment of optically active 2,3-epoxyalcohols with trialkylaluminum reagents followed by periodate cleavage constitutes a convenient synthesis of α-chiral aldehyde derivatives, especially when the branching alkyl group is methyl.
- Roush, William R.,Adam, Michael A.,Peseckis, Steven M.
-
p. 1377 - 1380
(2007/10/02)
-
- Total synthesis of (-)-maysine
-
A convergent synthesis of the natural macrocycle (-)-maysine (3) has been accomplished involving only a single separation of epimers at C-10. The scheme involved the preparation of three major fragments: (a) the western zone, 4; (b) the southern zone, 6;
- Meyers,Babiak,Campbell,et al.
-
p. 5015 - 5024
(2007/10/02)
-
- ENANTIOSELECTIVE SYNTHESIS OF C3-C10 FRAGMENT (NORTHEASTERN ZONE) OF MAYTANSINOIDS WITH 4-CHIRAL CENTERS (4S,5S,6R,7S)
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The major precursor to the maytansinoids containing 4 non-racemic chiral centers has been prepared in gram quantities, suitable for further synthesis.The route to (+)-1 was accomplished in 13 steps including several highly stereocontrolled reactions which
- Meyers, A. I.,Hudspeth, James P.
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p. 3925 - 3928
(2007/10/02)
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