- CuH-Catalyzed Asymmetric Conjugate Reductions of Acyclic Enones
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A powerful new reaction has been developed for the asymmetric 1, 4-reduction of prochiral enones (see scheme). The key ingredients in this exceedingly mild and straightforward procedure are catalytic quantities of CuH, a readily available nonracemic phosphane ligand such as that shown, and inexpensive polymethyl-hydrosiloxane (PMHS) as the stoichiometric source of hydride.
- Lipshutz, Bruce H.,Servesko, Jeff M.
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- Neutral iridium catalysts with chiral phosphine-carboxy ligands for asymmetric hydrogenation of unsaturated carboxylic acids
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We developed neutral iridium catalysts with chiral spiro phosphine-carboxy ligands (SpiroCAP) for asymmetric hydrogenation of unsaturated carboxylic acids. Different from the cationic Crabtree-type catalysts, the iridium catalysts with chiral spiro phosphine-carboxy ligands are neutral and do not require the use of a tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (BArF?) counterion, which is necessary for stabilizing cationic Crabtree-type catalysts. Another advantage of the neutral iridium catalysts is that they have high stability and have a long lifetime in air. The new iridium catalysts with chiral spiro phosphine-carboxy ligands exhibit unprecedented high enantioselectivity (up to 99.4% ee) in the asymmetric hydrogenations of various unsaturated carboxylic acids, particularly for 3-alkyl-3-methylenepropionic acids, which are challenging substrates for other chiral catalysts.
- Yang, Shuang,Che, Wen,Wu, Hui-Ling,Zhu, Shou-Fei,Zhou, Qi-Lin
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p. 1977 - 1980
(2017/03/09)
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- Syntheses of (R)- and (S)-3-methylheptanoic acids
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Starting from chiral methyl molecules 3 and 4, both derived from (R)-4-methyl-δ-valerolactone, we have accomplished the synthesis of (R) and (S)-3-methylheptanoic acids. Our methods are amendable to the syntheses of a wide variety of chiral 3-methyl alkanoic acids. Both enantiomers of 3-methylheptanoic acid have been synthesized from chiral methyl molecules which were derived from (R)-4-methyl-δ-valerolactone (5). A wide variety of chiral 3-methyl alkanoic acids can also be synthesized by the methods described herein.
- Zhang, Shunji,Shi, Yong,Tian, Weisheng
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supporting information
p. 674 - 678
(2015/06/25)
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- Anthracene cycloadducts as highly selective chiral auxiliaries
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(Chemical Equation Presented) A new chiral auxiliary was designed and easily prepared from a Diels-Alder cycloadduct of an enantiomerically pure anthracene with maleimide. Excellent diastereoselectivities in Diels-Alder reactions, conjugate additions, and aldol reactions employing these auxiliaries are now reported.
- Liu, Xiang,Snyder, John K.
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p. 2935 - 2938
(2008/09/19)
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- Asymmetric cascade reaction sequences via chiral lithiated intermediates
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(Chemical Equation Presented) The (-)-sparteine-mediated enantioselective intermolecular carbolithiation of (E)-2-propenylarylamines allows for the generation of chiral lithiated intermediates which have broad synthetic potential. These intermediates have been exploited in a series of further in situ reactions with electrophiles to generate a collection of products each containing a common stereogenic center. The stereogenic center, formed in high enantiomeric ratio in the first carbolithiation step, is carried through the cascade reaction sequence to the final products and is independent of electrophile used. The methodology is demonstrated by the synthesis of structurally diverse chiral anilines, indoles, and indolones all with an er of 92:8 (±1). The heterocyclic syntheses involve an enantioselective alkene carbolithiation and subsequent trapping of the intermediate organolithium with a suitable electrophile, followed by an in situ ring closure and dehydration to generate the indole or indolone rings.
- Hogan, Anne-Marie L.,O'Shea, Donal F.
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p. 2503 - 2509
(2008/09/19)
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- Applications of enantioselective carbolithiation of ortho-substituted β-methylstyrenes
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(Chemical Equation Presented) The enantioselective carbolithiation of ortho-substituted (E)-β-methylstyrenes provides access to chiral lithiated intermediates with broad synthetic potential. Specifically, β- methylstyrenes with o-aminomethyl, ether, and o
- Hogan, Anne-Marie L.,Tricotet, Thomas,Meek, Alastair,Khokhar, Shaista S.,O'Shea, Donal F.
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p. 6041 - 6044
(2008/12/21)
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- Rh-catalyzed highly enantioselective synthesis of 3-arylbutanoic acids
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(Chemical Equation Presented) It's in the mix: The reaction conditions - catalyst, additive, and solvent - have been optimized for the asymmetric hydrogenation of 3-aryl-3-butenoic acids. The rigid, chiral bisphospholane ligand (SP,RC)-DuanPhos is crucial to achieving high enantioselectivity.
- Sun, Xianfeng,Zhou, Le,Wang, Chun-Jiang,Zhang, Xumu
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p. 2623 - 2626
(2008/02/13)
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- (S,S)-(+)-pseudoephedrine as chiral auxiliary in asymmetric conjugate addition and tandem conjugate addition/α-alkylation reactions
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(Chemical Equation Presented) Organolithium reagents undergo highly regio- and diastereoselective 1,4-addition to (S,S)-(+)-pseudoephedrine enamides furnishing the corresponding β-alkyl-substituted adducts in excellent yields and diastereoselectivities. In addition, the intermediate lithium enolates generated after the conjugate addition step undergo a highly diastereoselective alkylation reaction, furnishing α,β-dialkyl- substituted amides in high yields. The obtained adducts have been converted into chiral nonracemic β-alkyl- and α,β-dialkyl-substituted carboxylic acids and γ-alkyl- and β,γ-dialkyl-substituted alcohols using very simple and high-yielding procedures.
- Reyes, Efraim,Vicario, Jose L.,Carrillo, Luisa,Badia, Dolores,Uria, Uxue,Iza, Ainara
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p. 7763 - 7772
(2007/10/03)
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- (R)-4-menthenone in the synthesis of optically pure sex pheromone of the peach leafminer moth (Lyonetia clerkella)
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The synthesis of (14S)-methyloctadec-1-ene, sex pheromone of the peach leafminer moth (Lyonetia clerkella), is described to demonstrate a new potential of the synthetic use of (R)-4-menthenone.
- Kharisov,Latypova,Talipov,Muslukhov,Ishmuratov,Tolstikov
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p. 2267 - 2269
(2007/10/03)
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- Semiochemicals of the Scarabaeinae: VI. Identification of EAD-active constituents of abdominal secretion of male dung beetle, Kheper nigroaeneus.
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Using gas chromatography with flame ionization detection (FID) and electroantennographic detection (EAD) in parallel, and employing chiral and achiral capillary columns, three constituents of the abdominal sex-attracting secretion of male Kheper nigroaeneus dung beetles were found to elicit reproducible EAD responses in male and female K. nigroaeneus antennae. One of these constituents is present in the secretion in such a small quantity that it could not be detected by FID, and it was not identified. The other constituents were identified as 3-methylindole (skatole) and (R)-(+)-3-methylheptanoic acid.
- Burger,Petersen
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p. 501 - 513
(2007/10/03)
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- The 1,4-addition of organometallic reagents to enoates derived from pinanediol
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The complex-induced, proximity effect-promoted 1,4-addition of RCu·BF3 and R2CuLi to enoates derived from (-)-pinanediol leads to adducts with the opposite sense of chirality (up to 98% d.e.).
- Pinheiro, Sergio,Pedraza, Sergio F.,Peralta, Monica A.,Teixeira, Rafael C.,De Farias, Florence M. C.,Ferreira, Vitor F.,Costa, Paulo R. R.
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p. 2513 - 2517
(2007/10/03)
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- Enantioselective carbometalation of cinnamyl derivatives: New access to chiral disubstituted cyclopropanes - Configurational stability of benzylic organozinc halides
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A stoichiometric or catalytic amount of (-)-sparteine can serve asa promoter for the enantioselective carbolithiation of cinnamyl derivatives by primary and secondary organolithium compounds. The enantiofacial choice of the addition reaction is dependent on the stereochemistry of the initial double bond. The resulting benzylic organolithium compounds can be derivatized to a linear phenylated chain that bears two contiguous stereogenic centers with given configurations. The use of the dimethyl acetal of the (E)-cinnamyl alcohol allows the highest enantioselective carbolithiation and by simply warming the reaction mixture to room temperature, the resulting benzylic organo-lithium intermediate undergoes a 1,3-elimination to give the chiral disubstituted cyclopropane in high enantiomeric excess (90-95% ee). Another significant finding is the observation that the Li-Zn transmetalation in a benzylic species occurs with inversion of configuration, and the corresponding acyclic benzylic zinc halides have observable configurational stability at - 30°C.
- Norsikian, Stephanie,Marek, Ilan,Klein, Sophie,Poisson, Jean F.,Normant, Jean F.
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p. 2055 - 2068
(2007/10/03)
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- Enantioselective carbolithiation of β-alkylated styrene
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Stoichiometric or catalytic amounts of (-) sparteine serve as promoter for enantioselective carbolithiation of β-alkylated, non functionalized styrene.
- Norsikian, Stephanie,Marek, Ilane,Normant, Jean-F.
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p. 7523 - 7526
(2007/10/03)
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- A practical synthesis of 3(S)-methyl-heptanoic acid from (S)-citronellol
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Chiral 3-methyl-heptanoic acid is readily accessible by functional group manipulation of optically active citronellol. In principle, this approach is general and could be applied to the synthesis of chiral 3-methyl-alkanoic acids seven carbon atoms in length and longer.
- Breitenbach, Ralph,Chiu, Charles K.-F.,Massett, Stephen S.,Meltz, Morgan,Murtiashaw, C. William,Pezzullo, Susan L.,Staigers, Thomas
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p. 435 - 442
(2007/10/03)
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- Dispiroketals in synthesis (Part 16): Functionalised dispiroketals as new chiral auxiliaries; the synthesis of dihydroxylated dispiroketals in optically pure form and their application as bifunctional , C2-symmetrical, chiral auxiliaries for highly stereoselective Michael additions
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A range of rigid, architecturally complex diols derived from dispiroketals have been synthesised.A bifunctional, C2-symmetrical, chiral auxiliary derived from these dihydroxylated dispiroketals has been used to induce a high degree of asymmetry in Michael additions of cuprates to a variety of di-α,β-unsaturated ester systems.
- Bezuidenhoudt, Barend C. B.,Castle, Grant H.,Innes, Jean E.,Ley, Steven V.
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p. 184 - 194
(2007/10/02)
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- Diastereoselectivity in Iodotrimethylsilane-promoted Conjugate Additions of Organocopper Reagents to Chiral α,β-Unsaturated Imides and Amides
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Conjugate additions of MeCu, PhCu and BuCu to the chiral enoylimides 2 a-c in the presence of iodotrimethylsilane and lithium iodide in THF give the adducts, 4a-c in yields above 90percent and diastereoselectivities from 80 to 93percent.The dominating diastereomers are different from those formed with LiR2Cu/TMSCl or in copper(I)-mediated addition of Grignard reagents.Corresponding additions to enoyl-amides of O-tritylprolinol also give high yields of conjugate adducts, but lower diastereoselectivities, with dominating configuration in the acyl part opposite to those from the imides.
- Bergdahl, Mikael,Iliefski, Tommy,Nilsson, Martin,Olsson, Thomas
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p. 3227 - 3230
(2007/10/02)
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- Dispiroketals in Synthesis (Part 14): Functionalised Dispiroketals as New Chiral Auxiliaries; Highly Stereoselective Michael Additions to a Bifunctional, C2-Symmetrical Chiral Auxiliary.
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A bifunctional, C2-symmetrical chiral auxiliary derived from dihydroxylated dispiroketals has been used to induce a high degree of asymmetry in Michael additions of cuprates to a variety of di-α,β-unsaturated ester systems.
- Castle, Grant H.,Ley, Steven V.
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p. 7455 - 7458
(2007/10/02)
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- Crystalline n-(s-3-methylheptanoyl)-D-gamma-glutamyl-glycyl-D-alanine, and processes and intermediates therefor
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A process and intermediates for the manufacture of S-3-methylheptanoic acid from S-citronellol; a novel crystalline form of immunoregulatory N-(S-3-methylheptanoyl)-D-gamma-glutamyl-glycyl-D-alanine, an immunoregulatory agent; and an improved process and intermediates therefor.
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- Processes and intermediates for N-(S-3-alkyl-heptanoyl)-D-gamma-glutamyl-D-alanine
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Immunoregulatory N-(S-3-alkyl-4-heptenoyl)- and N-(S-3-alkylheptanoyl)-D-gamma-glutamyl-glycyl-D-alanine and esters thereof are synthesized via R-trans-2-hexen-4-ols, R-3-alkyl-4-heptenoic acid and S-3-alkylheptanoic acid.
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- Processes and intermediates for N-(S-3-alkylheptanoyl)-D-gamma-glutamyl-glycyl-D-alanine
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Immunoregulatory N-(S-3-alkyl-4-heptenoyl)- and N-(S-3-alkylheptanoyl)-D-gamma-glutamyl-glycyl-D-alan-ine and esters thereof are synthesized via R-trans-2--hexen-4-ols, R-3-alkyl-4-heptenoic acid and S-3--alkylheptanoic acid.
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- Crystalline N-(S-3-methylheptanoyl)-D-gamma-glutamyl-glycyl-D-alanine, and processes and intermediates therefor
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A process and intermediates for the manufacture of S-3-methylheptanoic acid from S-citronellol; a novel crystalline form of immunoregulatory N-(S-3-methyl--heptanoyl)-D-gamma-glutamyl-glycyl-D-alanine, an immunoregulatory agent; and an improved process and intermediates therefor.
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- Asymmetric Conjugate Addition to Unsaturated Chiral Amido Alcohols Using Grignard Reagents Co-ordinated with Tertiary Amines or DBU. Preparation of Optically Active 3-Substituted Carboxylic Acids and (S)-(-)-Citronellol
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Optically active 3-substituted carboxylic acids and (S)-(-)-citronellol have been obtained by diastereoselective conjugate addition of Grignard reagents co-ordinated with 1,8-diazabicyclo-undec-7-ene (DBU) to chiral amidoalcohols derived from (S)-proline.
- Soai, Kenso,Machida, Hideaki,Yokota, Noriko
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p. 1909 - 1914
(2007/10/02)
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- ASYMMETRIC CONJUGATE ADDITION REACTION BY THE USE OF (S)-γ-TRITYLOXYMETHYL-γ-BUTYROLACTAM AS A CHIRAL AUXILIARY
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(S)-γ-Trityloxymethyl-γ-butyrolactam (2) serves as a chiral auxiliary in the conjugate addition reaction of the corresponding imide (3) of α,β-unsaturated carboxylic acids with Grignard reagents in the presence of CuBr-SMe2 in THF to give, after hydrolysis, the β,β-disubstituted carboxylic acids (5) with predictable absolute configuration and high enantiomeric excess.
- Tomioka, Kiyoshi,Suenaga, Toshiro,Koga, Kenji
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p. 369 - 372
(2007/10/02)
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- EFFICIENT ASYMMETRIC HYDROGENATIONS OF CAMPHOR-SULTAM-IMIDE-CONJUGATED ALKENES.
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The trisubstituted olefinic bond of sultam-imides 2 was hydrogenated in the presence of Pd/C with >90percent diastereoface discrimination to give after saponification recovered auxiliary 7 and the β-substituted carboxylic acids 5 or 6 in high e.e..
- Oppolzer, Wolfgang,Mills, Robert J.,Reglier, Marius
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p. 183 - 186
(2007/10/02)
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- Asymmetric Conjugate Addition of Organometallic Reagents to Chiral Vinyl Sulfoximines
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The chiral vinyl sulfoximines 1 and 2 (R' = C6H5, CH3, n-Bu, C6H5CH2CH2) have been prepared; they undergo conjugate addition reactions with organometallic reagents with high asymmetric induction.These conjugate addition adducts have been converted to chiral 3-alkylalkanoic acids in high enantiomeric excess (>90percent)
- Pyne, Stephen G.
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- Camphorsulfonamide-Shielded, Asymmetric 1,4-Additions and Enolate Alkylations; Synthesis of a Southern Corn Rootworm Pheromone
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Using readily accessible 10-sulfonamido-isoborneols as regenerable, chiral auxiliaries, highly face-selective C-C-bond formations at Cα and Cβ of carboxylates could be conveniently achieved.Thus, conjugated additions of RCu to enoates (1->2) furnished, after saponification, β-substituted carboxylic acids 3 in 94-98 percent e.e.Similarly, propionates 12 yielded after deprotonation, enolate alkylation, and reductive ester cleveage the (R)-alcohols 15 in 78-98 percent e.e.The acid (+)-3e was converted to the pheromone (-)-11.
- Oppolzer, Wolfgang,Dudfield, Philip,Stevenson, Thomas,Godel, Thierry
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p. 212 - 215
(2007/10/02)
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- High Asymmetric Induction in Conjugate Additions of RCu*BF3 to Chiral Enoates
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1,4-Additions of PhCu*BF3, n-BuCu*BF3 and MeCu*BF3 to the trans-8-phenylmenthyl enoates 1 proceeded with high chiral induction.Saponification of the resulting esters 2 gave the corresponding enantiomerically pure β-substituted alkanoic acids 3 and the recovered (-)-8-phenylmenthol in good overall yields.Analogous additions to the cis-crotonate 1 led preferentially to the acids 3 enantiomeric to those obtained from the trans-crotonate 1, although with lower selectivity.A stereochemical model is proposed consistent with the observed results (Scheme 2, Table).
- Opplzer, Wolfgang,Loeher, Heinz J.
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p. 2808 - 2811
(2007/10/02)
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- A FACILE ASYMMETRIC SYNTHESIS OF β-SUBSTITUTED ALKANOIC ACID. THE HIGHLY STEREOSELECTIVE MICHAEL ADDITION OF GRIGNARD REAGENTS TO α,β-UNSATURATED CARBOXYLIC AMIDES DERIVED FROM L-EPHEDRINE
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The Michael addition of Grignard reagents to chiral α,β-unsaturated carboxylic amides derived from l-ephedrine affords highly optically active β-substituted alkanoic acids after acid hydrolysis.This high stereoselectivity is explained by considering the formation of rigid internal chelate complexes.
- Mukaiyama, Teruaki,Iwasawa, Nobuharu
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p. 913 - 916
(2007/10/02)
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