- Palladium-Catalyzed Asymmetric Decarboxylative Addition of β-Keto Acids to Heteroatom-Substituted Allenes
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The Pd-catalyzed asymmetric addition reaction of β-keto acids to heteroatom-substituted allene is reported. This reaction generates β-substituted ketones in an asymmetric manner through a branch-selective decarboxylative allylation pathway. The reaction accommodates various alkoxyallenes as well as amidoallenes.
- Jang, Dong-Jin,Lee, Sukhyun,Lee, Juyeol,Moon, Dohyun,Rhee, Young Ho
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Read Online
- Development of a robust immobilized organocatalyst for the redox-neutral mitsunobu reaction
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A polystyrene-supported version of the Denton catalyst for redox-neutral Mitsunobu reactions, (2-hydroxybenzyl)diphenylphosphine oxide, has been developed and used in catalytic inversion of enantiopure secondary alcohols (21 examples, up to 97% yield and 98% ee) with 2-nitrobenzoic and 2,4-dinitrobenzoic acids. The use in the reaction of alternative pronucleophiles has also been explored (8 successful and 3 unsuccessful examples). The functional resin shows high recyclability (10 cycles, 30 days operation) and can be re-activated by simple treatment with butylamine with further extension of its useful life.
- Lai, Junshan,Llanes, Patricia,Mastandrea, Marco M.,Pericàs, Miquel A.,Perulli, Stefania,Zhou, Leijie
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p. 8859 - 8864
(2021/11/23)
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- Enantioselective addition of diethylzinc to aldehydes catalyzed by 5-cis-substituted proline derivatives
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5-Cis-substituted prolinols, prolinamines, and prolinamine sulfonamides proved to be efficient ligands for the enantioselective addition of diethylzinc to aldehydes, providing up to 99% ee. The sense of asymmetric induction can be controlled by the nature
- Prause, Felix,Wagner, Stefan,Breuning, Matthias
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- Chiral zinc amidate catalyzed additions of diethylzinc to aldehydes
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A series of bifunctional spiro ligands bearing “carboxamide–phosphine oxide” groups and ethylzinc carboxamidates from these ligands as catalysts for Et2Zn additions to aldehydes were reported. Excellent yields were obtained with moderate ee′s in Et2Zn additions to benzaldehyde derivatives, implying effectiveness of our newly designed catalytic structures as well as mediocre stereocontrol by these chiral ligands. Possible transition states were suggested based on the crystal structures of two ligands.
- Zhang, Jinxia,Li, Shasha,Zheng, Xinxin,Li, Hongjie,Jiao, Peng
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supporting information
p. 1913 - 1917
(2019/06/24)
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- Investigation of the Deprotonative Generation and Borylation of Diamine-Ligated α-Lithiated Carbamates and Benzoates by in Situ IR spectroscopy
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Diamine-mediated α-deprotonation of O-alkyl carbamates or benzoates with alkyllithium reagents, trapping of the carbanion with organoboron compounds, and 1,2-metalate rearrangement of the resulting boronate complex are the primary steps by which organoboron compounds can be stereoselectively homologated. Although the final step can be easily monitored by 11B NMR spectroscopy, the first two steps, which are typically carried out at cryogenic temperatures, are less well understood owing to the requirement for specialized analytical techniques. Investigation of these steps by in situ IR spectroscopy has provided invaluable data for optimizing the homologation reactions of organoboron compounds. Although the deprotonation of benzoates in noncoordinating solvents is faster than that in ethereal solvents, the deprotonation of carbamates shows the opposite trend, a difference that has its origin in the propensity of carbamates to form inactive parasitic complexes with the diamine-ligated alkyllithium reagent. Borylation of bulky diamine-ligated lithiated species in toluene is extremely slow, owing to the requirement for initial complexation of the oxygen atoms of the diol ligand on boron with the lithium ion prior to boron-lithium exchange. However, ethereal solvent, or very small amounts of THF, facilitate precomplexation through initial displacement of the bulky diamines coordinated to the lithium ion. Comparison of the carbonyl stretching frequencies of boronates derived from pinacol boronic esters with those derived from trialkylboranes suggests that the displaced lithium ion is residing on the pinacol oxygen atoms and the benzoate/carbamate carbonyl group, respectively, explaining, at least in part, the faster 1,2-metalate rearrangements of boronates derived from the trialkylboranes.
- Mykura, Rory C.,Veth, Simon,Varela, Ana,Dewis, Lydia,Farndon, Joshua J.,Myers, Eddie L.,Aggarwal, Varinder K.
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supporting information
p. 14677 - 14686
(2018/11/20)
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- Chiral Lithium Amido Zincates for Enantioselective 1,2-Additions: Auto-assembling Reagents Involving a Fully Recyclable Ligand
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A methodology consisting in carrying out enantioselective nucleophilic 1,2-additions (ee values up to 97 %) from cheap, easily accessible, and never described before, chiral lithium amido zincates is presented. These multicomponent reactants auto-assemble when mixing, in a 1:1 ratio, a homoleptic diorganozinc (R2Zn) with a chiral lithium amide (CLA). The latter, obtained after a single reductive amination, plays the role of the chiral inductor and is fully recoverable thanks to a simple acid–base wash, allowing being recycled and re-use without loss of stereochemical information.
- Rouen, Mathieu,Chaumont, Pauline,Barozzino-Consiglio, Gabriella,Maddaluno, Jacques,Harrison-Marchand, Anne
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supporting information
p. 9238 - 9242
(2018/06/04)
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- Noscapine Derivatives as New Chiral Catalysts in Asymmetric Synthesis: Highly Enantioselective Addition of Diethylzinc to Aldehydes
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Noscapine, a natural alkaloid, has never been used as a parent scaffold in chiral induction. The first examples of noscapinoid compounds as efficient catalysts in asymmetric synthesis are now reported. Three derivatives of noscapine were synthesized from its reaction with different Grignard reagents. Asymmetric addition of diethylzinc to aldehydes was performed in the presence of these catalysts in high yields and good to excellentees.
- Mohebbi, Maryam,Bararjanian, Morteza,Ebrahimi, Samad N.,Smie?ko, Martin,Salehi, Peyman
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p. 1841 - 1848
(2018/02/14)
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- Enantioselective addition of diethylzinc to aldehydes catalyzed by o-xylylene-type chiral 1,4-amino alcohols with an aminal structure
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A series of o-xylylene-type chiral 1,4-amino alcohols with an aminal structure was synthesized starting from (S)-2-(arylaminomethyl)pyrrolidine, o-bromobenzaldehyde, and a diaryl ketone. The enantioselective addition of diethylzinc to aldehydes was examined by using the 1,4-amino alcohols, and the corresponding chiral secondary alcohols were obtained with high enantioselectivities (up to 98% ee).
- Asami, Masatoshi,Hasome, Ayano,Yachi, Naoyuki,Hosoda, Naoya,Yamaguchi, Yoshitaka,Ito, Suguru
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p. 322 - 329
(2016/04/09)
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- Enantioselective addition of organozinc reagents to carbonyl compounds catalyzed by a camphor derived chiral γ-amino thiol ligand
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In this article, the design and synthesis of the chiral camphor derived γ-amino thiol ligand 17 and its application in catalytic enantioselective carbon-carbon forming reactions through the addition of organozinc reagents to carbonyl compounds is described. The catalytic activity and enantioselectivity of ligand 17 is demonstrated in the enantioselective addition of various organozinc reagents to aldehydes and ketoesters, offering the corresponding alcohols in high yields and enantioselectivities. The role of the mercapto group in the highly enantioselective 1,2-addition reaction of organozincs to aldehyde is also discussed.
- Wu, Hsyueh-Liang,Wu, Ping-Yu,Cheng, Ying-Ni,Uang, Biing-Jiun
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p. 2656 - 2665
(2016/05/10)
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- D-Penicillamine and L-cysteine derived thiazolidine catalysts: an efficient approach to both enantiomers of secondary alcohols
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D-Penicillamine derived thiazolidine ligands were prepared in a two-step synthetic sequence and used in the enantioselective alkylation of a variety of aromatic aldehydes with diethylzinc at room temperature. Excellent ee, up to >99%, and nearly complete conversions were observed. Structurally analogous L-cysteine derived thiazolidine ligands were also synthesized and tested for comparative purposes, resulting in very good, albeit slightly lower selectivities, up to 89%. The combined use of these two types of thiazolidines constitutes a very interesting strategy for synthesizing both (S) and (R) enantiomers of chiral secondary alcohols, thus leading the way to a myriad of useful optically active products with opposite absolute configurations.
- Serra, M. Elisa Silva,Costa, Dora,Murtinho, Dina,Tavares, Nélia C.T.,Pinho e Melo, Teresa M.V.D.
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p. 5923 - 5927
(2016/09/07)
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- Rhodium-Catalyzed Enantioselective Intermolecular Hydroalkoxylation of Allenes and Alkynes with Alcohols: Synthesis of Branched Allylic Ethers
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Regio- and enantioselective additions of alcohols to either terminal allenes or internal alkynes provides access to allylic ethers by using a RhI/diphenyl phosphate catalytic system. This method provides an atom-economic way to obtain chiral aliphatic and aryl allylic ethers in moderate to good yield with good to excellent enantioselectivities.
- Liu, Zi,Breit, Bernhard
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p. 8440 - 8443
(2016/07/19)
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- Preparation of several BINOL-based polymeric ligands for the enantioselective addition of triethylaluminium to aromatic aldehydes
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The synthesis of several polystyrene-supported BINOL (1,1-binaphthol) ligands via radical polymerization is described. These BINOL-based polymeric ligands were applied to the enantioselective addition of triethylaluminium to aromatic aldehyde in the presence of titanium isopropoxide. The products were obtained with up to 93% enantiomeric excess (ee) in good to excellent yield. The ligands were easily recovered and reused without losing their catalytic activity as well as enantioselectivity.
- Liu, Dacai,Ouyang, Kunbing,Yang, Nianfa
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p. 1018 - 1023
(2016/01/30)
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- Enantioselective addition of diethylzinc to aldehydes catalyzed by diastereomeric 1,4-amino alcohols with o-xylylene skeleton
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Two diastereomeric 1,4-amino alcohols with o-xylylene structure (S,R)-2 and (S,S)-3, synthesized from chiral 1,4-diol (S,S)-1, were utilized as chiral ligands for the enantioselective addition of diethylzinc to aldehydes. The stereochemical outcome of the reactions was controlled solely by the absolute configuration of the benzylic carbon bearing amino group, and both enantiomers of 1-substituted propanol were obtained with up to 98% (S) and 96% (R) enantiomeric excesses.
- Asami, Masatoshi,Nagai, Atsushi,Sasahara, Yukihiro,Ichikawa, Ken-Ichi,Ito, Suguru,Hosoda, Naoya
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supporting information
p. 345 - 347
(2015/03/30)
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- Enantioselective addition of diethylzinc to aldehydes catalyzed by (R)-1-phenylethylamine-derived 1,4-amino alcohols
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A series of o-xylylene-type 1,4-amino alcohols, synthesized from (R)-1-phenylethylamine, were used as chiral ligands for the enantioselective addition of diethylzinc to benzaldehyde. (S)-1-Phenyl-1-propanol was obtained with high enantioselectivity in all cases since the stereochemical outcome of the reaction was controlled by the chiral benzylic carbon bearing amino group. Highest catalytic activity was obtained by using (R)-1-{2-[1-(pyrrolidin-1-yl)ethyl]phenyl}cyclohexan-1-ol (1n) derived from (R)-1-(1-phenylethyl)pyrrolidine and cyclohexanone. Various chiral secondary alcohols were obtained by the reaction of diethylzinc and aldehydes in the presence of 1n within 2 h with good to high enantioselectivities.
- Asami, Masatoshi,Miyairi, Naomichi,Sasahara, Yukihiro,Ichikawa, Ken-Ichi,Hosoda, Naoya,Ito, Suguru
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p. 6796 - 6802
(2015/08/24)
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- The synthesis of chiral amino diol tridentate ligands and their enantioselective induction during the addition of diethylzinc to aldehydes
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A series of C2-symmetric chiral amino diol tridentate ligands 3a-g were prepared from achiral bulky organolithiums, achiral bulky primary amines, and optically active epichlorohydrin (ECH). The prepared C 2-symmetric chiral amino diol tridentate ligands were capable of inducing enantioselectivity in the model reaction of aromatic and aliphatic aldehydes with diethylzinc with an ee of up to 96%. The enantioselectivity can be modulated by adjusting the steric hindrance of the achiral reagents employed in the synthesis of the chiral ligand. The configuration of the addition product depended on the configuration of the amino diol ligands, which can be simply controlled as desired by using the ECH with the desired configuration during the preparation of the ligand.
- Zhang, An-Lin,Yang, Li-Wen,Yang, Nian-Fa,Liu, Yan-Ling
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p. 289 - 297
(2014/04/03)
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- Enantioselective alkylation of aldehydes using dialkylzincs catalyzed by simple chiral diols derived from naturally occurring monosaccharides
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Enantioselective alkylation of aldehydes was achieved in up to 84% ee using dialkylzincs catalyzed by simple diols derived from naturally occurring monosaccharides.
- Michigami, Kyosuke,Hayashi, Masahiko
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supporting information
p. 4221 - 4225
(2013/06/27)
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- Polymer-supported chiral α-amino amides for the asymmetric addition of diethylzinc to aldehydes: Transforming an inactive homogeneous system into an efficient catalyst
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A series of polymer-supported α-amino amides derived from natural amino acids have been easily synthesized and fully characterized. Their chiral Zn (II) complexes catalyzed the enantioselective addition of diethylzinc to aldehydes to form chiral secondary alcohols in high yields and enantioselectivities up to 95% were obtained. The results showed that the immobilization of this chiral ligand onto a polymeric matrix transforms the inactive homogeneous system into an efficient catalyst. Moreover, the supported catalyst could be re-used at least five times without any significant loss of catalytic activity.
- Escorihuela, Jorge,González, Laura,Altava, Belén,Burguete, M. Isabel,Luis, Santiago V.
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- Synthesis of enantioenriched tertiary boronic esters by the lithiation/borylation of secondary alkyl benzoates
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Simple, secondary 2,4,6-triisopropyl benzoates (TIB esters) and secondary dialkyl N,N-diisopropyl carbamates have been reported to be resistant to deprotonation by strong bases. We have found that the combination of sBuLi (1.6 equiv) and TMEDA (6 equiv) in CPME at -60 C enables deprotonation of unactivated secondary dialkyl TIB esters, but not the carbamates. These carbanions were reacted with a range of neopentyl boronic esters which, after 1,2-metalate rearrangement and oxidation, gave a range of tertiary alcohols in high yield and universally high er. Further functional group transformations of the tertiary boronic esters were demonstrated (conversion to quaternary centers, C-tertiary amines) together with application of the methodology to the synthesis of the simplest unbranched hydrocarbon bearing a quaternary center, (R)-4-ethyl-4-methyloctane, validating the synthetic utility of the methodology.
- Pulis, Alexander P.,Blair, Daniel J.,Torres, Eva,Aggarwal, Varinder K.
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supporting information
p. 16054 - 16057
(2013/11/19)
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- Polystyrene-supported (2S)-(-)-3-exo-piperazinoisoborneol: An efficient catalyst for the batch and continuous flow production of enantiopure alcohols
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A polystyrene-supported analog (PS-PIB) of 3-exo-morpholinoisoborneol (MIB), designed for increased chemical stability, has been synthesized and used as a ligand in the asymmetric alkylation of aldehydes with Et2Zn. The supported ligand turned out to be highly active and enantioselective for a broad scope of substrates (92-99% ee), allowing repeated recycling. A single-pass, continuous flow process implemented with PS-PIB shows only a marginal decrease in conversion after 30 h of operation.
- Osorio-Planes, Laura,Rodriguez-Escrich, Carles,Pericas, Miquel A.
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supporting information; experimental part
p. 1816 - 1819
(2012/07/03)
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- Enantioselective addition of diethylzinc to aldehydes catalyzed by (S)-1-alkyl-2-(arylamino)methylpyrrolidine
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Several chiral diamines, (S)-1-alkyl-2-(arylamino)methylpyrrolidine, were used as chiral catalysts for the enantioselective addition of diethylzinc to aldehydes. The best results were obtained by employing 0.15 equiv of (S)-2-anilinomethyl-1-benzylpyrrolidine, and chiral secondary alcohols were obtained with high enantiomeric excesses (up to 94% ee).
- Hosoda, Naoya,Ito, Hiroki,Takimoto, Tatsuya,Asami, Masatoshi
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p. 1014 - 1022
(2012/11/07)
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- Enantioselective addition of dialkylzincs to aldehydes catalyzed by (-)-MITH
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An effective catalytic system that imparts high enantioselectivity has been disclosed for the synthesis of optically active alcohols, which may undergo further chemical transformations. The enantioselective alkylation of aldehydes with dialkylzincs to afford the corresponding optically active alcohols with excellent enantioselectvities has been achieved in the presence of 0.1-0.5 mol % of the camphor-derived chiral ligand (-)-2-exo-morpholinoisobornane-10-thiol (MITH) (1) at room temperature or at 0 °C. I zinc so too: The enantioselective alkylation of aldehydes with dialkylzincs yielded the desired alcohol products with up to 99 % ee in the presence of 0.1-0.5 mol % of ligand (-)-2-exo-morpholinoisoborne-10-thiol (1) at room temperature or at 0°C. Copyright
- Cheng, Ying-Ni,Wu, Hsyueh-Liang,Wu, Ping-Yu,Shen, Ying-Ying,Uang, Biing-Jiun
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supporting information
p. 2921 - 2924
(2013/02/22)
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- Enantioselective addition of diethylzinc to aldehydes by chiral oxazolidine-titanium complex
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A series of chiral oxazolidines derived from (1R, 2S)-cis-1-amino-2-indanol was found to be effective in promoting the asymmetric addition of diethylzinc to aldehydes. Among the ligands developed, it was found that ligand 1b in the presence of Ti(OiPr)4 yielded the highest enantioselectivities when it was applied in the catalytic asymmetric addition of diethylzinc to aldehydes (up to 91% ee).
- Wu, Nan,Bo, Rongcheng,Zhang, Rongli,Jiang, Xi,Wan, Yu,Xu, Zhou,Wu, Hui
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p. 644 - 649
(2013/02/23)
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- Use of alkyl 2,4,6-triisopropylbenzoates in the asymmetric homologation of challenging boronic esters
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(-)-Sparteine induced lithiation of primary 2,4,6-triisopropylbenzoates and subsequent homologation of boronic esters is reported. A comparative study with lithiated N,N-diisopropylcarbamates has demonstrated the superiority of the hindered benzoate. The Royal Society of Chemistry 2011.
- Larouche-Gauthier, Robin,Fletcher, Catherine J.,Couto, Irantzu,Aggarwal, Varinder K.
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supporting information; experimental part
p. 12592 - 12594
(2012/01/05)
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- Switching of enantioselectivity in the catalytic addition of diethylzinc to aldehydes by regioisomeric chiral 1,3-amino sulfonamide ligands
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Twenty chiral 1,3-amino sulfonamides of two classes (2a-i and 3a-k) have been prepared from (-)-cis-2-benzamidocyclohexanecarboxylic acid (1) and studied as ligands for catalytic enantioselective addition of Et2Zn to a variety of aromatic and aliphatic aldehydes. The ligands 2 and 3 are regioisomers in which the position of the amine and sulfonamide groups is exchanged. Each class of ligands with the same chirality was shown to afford sec-alcohols with the opposite stereochemistry. Structural surveys revealed that the combination of tertiary amino and p-toluenesufonylamido groups works most effectively for the reaction. Through optimization of the structural and reaction conditions, the best ligands quantitatively provided both enantiomeric secondary alcohols in good to excellent enantioselectivity of up to 94% and 98% ee for (S)- and (R)-enantiomers, respectively.
- Hirose, Takuji,Sugawara, Kazuyuki,Kodama, Koichi
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experimental part
p. 5413 - 5428
(2011/08/05)
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- Applications of conformational design: Rational resign of chiral ligands derived from a common chiral source for highly enantioselective preparations of (R)- and (S)-enantiomers of secondary alcohols
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A pair of diastereomers 7 and 8 were easily synthesized in only two steps from a single common chiral source according to the concept of conformation design. The efficiency of these chiral ligands was evaluated by their application to the asymmetric addition of diethylzinc to aldehydes. This catalytic asymmetric process afforded the a most efficient access to the (R)- and (S)-enantiomers of a given secondary alcohol with similarly outstanding enantioselectivities and high yields. Our results also showed that the control of the desired conformer's population by conformation design is a new and practical strategy for the rational and precise design of highly enantioselective chiral ligands for metal-catalyzed reactions. The mechanism and possible transition states for the catalytic asymmetric addition have been proposed on the basis of previous studies as well as the crystal structure of the chiral ligands 7 and 8.
- Wang, Min-Can,Wang, Yong-Hui,Li, Gao-Wei,Sun, Ping-Ping,Tian, Jie-Xi,Lu, Hui-Jie
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experimental part
p. 761 - 768
(2011/08/06)
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- L-proline-derived tertiary amino alcohols as chiral ligands for enantioselective addition of diethylzinc to aldehydes
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A series of L-proline derived tertiary amino alcohols was used as chiral ligands in the asymmetric addition reaction of Et2Zn to aldehydes. Among these ligands, it was found that ligand 1b which has the biggest steric and electrondonating substituent at the nitrogen position yielded the highest enantioselectivities when applied in the catalytic asymmetric addition of diethylzinc to p-chlorobenzadehyde. The experiment results of our paper may supply useful experience to help in revealing the relationship between ligand structure and ee values of the products.
- Xu, Zhou,Bo, Rongcheng,Wu, Nan,Wan, Yu,Wu, Hui
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experimental part
p. 582 - 586
(2012/05/31)
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- (1R,5R)-1-(1-dimethylaminoethyl)-2-isopropylidene-5-methylcyclohexanol as a chiral ligand in the enantioselective addition of diethylzinc to aldehydes
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An efficient chiral ligand, (1R,5R)-1-(1-dimethylaminoethyl)-2- isopropylidene-5-methylcyclohexanol, has been developed for the enantioselective addition of diethylzinc to some prochiral aldehydes to afford S-alcohols. The overall conversion rate was 80-98% with excellent enantiomeric excess (79-98%). Georg Thieme Verlag Stuttgart ? New York.
- Yadav, Ashok K.,Kumar, Manoj,Yadav, Tripti,Jain, Renuka
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scheme or table
p. 712 - 714
(2010/06/13)
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- Synthesis, resolution, and applications of 3-amino-2,2-dimethyl-1,3- diphenylpropan-1-ol, a conformationally restricted 1,3-aminoalcohol
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Efficient synthetic routes to both syn and anti diastereomers of a conformationally restricted 1,3-aminoalcohol were devised. Resolution of the aminoalcohols was accomplished through diastereomeric salt with R-(-)-O-acetyl mandelic acid. These aminoalcoho
- Patil,Gonnade,Joshi
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scheme or table
p. 5036 - 5041
(2010/08/20)
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- Highly enantioselective addition of diethylzinc to aldehydes catalyzed by novel chiral tert-amino alcohols
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A series of novel chiral tert-amino alcohols 4a-h derived from enantiomerically pure phenylalanine were synthesized efficiently and used as chiral ligands in the catalytic enantioselective ethylation of aldehydes with diethylzinc (diethylzinc-to-aldehyde addition). The use of 10 mol % of the amino alcohols led to the corresponding sec-alcohols with excellent enantioselectivities (up to 100% ee) and high yields.
- Zhang, Cong-Hai,Yan, Sheng-Jiao,Pan, Sheng-Qiang,Huang, Rong,Lin, Jun
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experimental part
p. 869 - 873
(2010/10/04)
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- NICOTINE-BASED COMPOUNDS USEFUL FOR ASYMMETRIC SYNTHESIS
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Chiral amino alcohol and amino phosphine compounds are provided herein, which compounds are useful for asymmetric synthesis.
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Page/Page column 35-40
(2010/04/27)
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- Improved method for the conversion of pinacolboronic esters into trifluoroborate salts: facile synthesis of chiral secondary and tertiary trifluoroborates
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A general method for the preparation of virtually any potassium trifluoroborate salt from the corresponding pinacolboronic ester is reported. Thus, conditions for an azeotropic removal of pinacol from the reaction mixture were found to afford the desired potassium trifluoroborates of sufficient purity (>95%) in nearly quantitative yields irrespective of the nature of the product. The utility of this method is illustrated by the preparation of a broad range of enantioenriched secondary and tertiary potassium trifluoroborates.
- Bagutski, Viktor,Ros, Abel,Aggarwal, Varinder K.
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supporting information; experimental part
p. 9956 - 9960
(2010/02/27)
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- Rapid screening for asymmetric catalysts: The efficient connection of two different catalytic asymmetric reactions
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A screening method for asymmetric catalysts is reported in which a metal-containing optically-active product of an asymmetric reaction is employed as a chiral catalyst in another asymmetric reaction; the rapid preparation and instant testing system of cat
- Yoshida, Kazuhiro,Toyoshima, Takeharu,Akashi, Naohisa,Imamoto, Tsuneo,Yanagisawa, Akira
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supporting information; experimental part
p. 2923 - 2925
(2009/11/30)
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- Chiral amino alcohols derived from (S)-6-chloronicotine as catalysts for asymmetric synthesis
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Commercially available (S)-nicotine was converted in two or three synthetic steps to various chiral amino alcohols. These nicotine derivatives were evaluated as potential chiral ligands for metal-catalyzed asymmetric reactions by using the addition of die
- Capracotta, Sonja S.,Comins, Daniel L.
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scheme or table
p. 1806 - 1808
(2009/07/17)
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- The synthesis of new oxazoline-containing bifunctional catalysts and their application in the addition of diethylzinc to aldehydes
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The straightforward preparation of new modular oxazoline-containing bifunctional catalysts is reported employing a microwave-assisted Buchwald-Hartwig aryl amination as the key step. Covalent attachment of 2-(o-aminophenyl)oxazolines and pyridine derivati
- Coeffard, Vincent,Mueller-Bunz, Helge,Guiry, Patrick J.
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experimental part
p. 1723 - 1734
(2009/06/27)
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- Synthesis of camphorsulfonamide-based quinoline ligands and their N-oxides: first use in the enantioselective addition of organozinc reagents to aldehydes
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The preparation of several camphorsulfonamide-based quinoline derivatives and their N-oxides was accomplished via an indirect Friedlaender synthesis using aminobenzylic alcohols and RuCl2(DMSO)4 as a catalyst. These ligands were tested in the enantioselective addition of dialkylzinc reagents to aldehydes, with enantiomeric excesses up to 96%. A similar protocol using triphenylborane and diethylzinc gave the corresponding phenylation process.
- Martinez, Ricardo,Zoli, Luca,Cozzi, Pier Giorgio,Ramon, Diego J.,Yus, Miguel
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experimental part
p. 2600 - 2607
(2009/04/11)
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- The first enantioselective addition of diethylzinc to aldehydes in ionic liquids catalysed by a recyclable ion-tagged diphenylprolinol
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The new procedure for the asymmetric addition of diethylzinc to aryl aldehydes in room-temperature ionic liquids (RTILs) was developed, in the field of chemical synthesis and catalysis. The use of tailored catalysts for metathesis, cross coupling and hydroformylation reactions in RTILs was also explored. A solution of diethylzinc was added to a solution of catalyst 1d and the mixture was stirred at RT for 5 min. The reaction was quenched with a few drops of water and resulting mixture was directly on the top of a silica gel column diluting with CH2Cl2. The results showed that the diphenylprolinol-derived 1d is a promising candidate to accelerate the asymmetric addition of diethylzinc to aromatic aldehydes. This also showed that operation is simple and efficient and is easily recyclable, making use of 10 mol% loading of 1d.
- Lombardo, Marco,Chiarucci, Michel,Trombini, Claudio
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scheme or table
p. 11288 - 11291
(2009/10/23)
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- Structural optimization of enantiopure 2-cyclialkylamino-2-aryl-1,1- diphenylethanols as catalytic ligands for enantioselective additions to aldehydes
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(Chemical Equation Presented) The structural optimization of a family of modular, enantiopure β-amino alcohol ligands with a common 2-amino-2-aryl-1,1-diphenylethanol skeleton, whose stereogenicity was introduced through the Jacobsen epoxidation of 1,1-diphenyl-2-arylethylenes, has led to the identification of a small set of optimal catalysts with enhanced activity and enantioselectivity in the addition of alkylzinc and arylzinc reagents to aldehydes. Criteria for the discrimination between apparently analogous, highly enantioselective ligands are proposed.
- Rodriguez-Escrich, Sergi,Reddy, Katamreddy Subba,Jimeno, Ciril,Colet, Gisela,Rodriguez-Escrich, Carles,Sola, Lluis,Vidal-Ferran, Anton,Pericas, Miquel A.
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p. 5340 - 5353
(2008/12/20)
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- Synthesis of novel chiral tridentate aminophenol ligands for enantioselective addition of diethylzinc to aldehydes
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Novel chiral tridentate aminophenol ligand (S)-3a was obtained by a Mannich-type reaction of cresol, paraformaldehyde, and (S)-1-(2-methoxyphenyl)-2-methylpropan-1-amine followed by a deprotection step. This tridentate aminophenol ligand shows high yield and enantioselectivity in the diethylzinc additions to a broad range of substrates, including alkyl, aryl, and α,β-unsaturated aldehydes.
- Yang, Xiao-Feng,Hirose, Takuji,Zhang, Guang-You
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p. 1670 - 1675
(2008/12/20)
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- Oxazaborolidine-catalyzed enantioselective reduction of α-methylene ketones to allylic alcohols
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(Chemical Equation Presented) Oxazaborolidine-catalyzed enantioselective reduction of α-methylene ketones was efficiently carried out by using borane-diethylaniline as a stoichiometric reducing agent. The combination of this method and subsequent hydrogen
- Matsuo, Jun-Ichi,Kozai, Takaaki,Nishikawa, Osamu,Hattori, Yu,Ishibashi, Hiroyuki
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p. 6902 - 6904
(2008/12/22)
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- Catalytic asymmetric alkylation of aldehydes with Grignard reagents
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(Chemical Equation Presented) Added benefits: Grignard reagents can be employed in the asymmetric alkylation of aldehydes by using a titanium(IV) catalyst derived from binol in the presence of excess titanium tetraisopropoxide (see scheme). The reaction proceeds with a low catalyst loading (2 mol%) and exhibits high enantioselectivity for both aromatic and unsaturated aldehydes and for both alkyl and aryl Grignard reagents.
- Muramatsu, Yusuke,Harada, Toshiro
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p. 1088 - 1090
(2008/09/21)
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- Lithiated carbamates: Chiral carbenoids for iterative homologation of boranes and boronic esters
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(Chemical Equation Presented) Take your pick: Either enantiomer of either diastereomer of substrates bearing adjacent stereogenic centers is accessible through reaction of an (R)- or (S)-lithiated carbamate with an (R)- or (S)-boronic ester (see scheme; pin = pinacolate, OCb = substituted carbamate).
- Stymiest, Jake L.,Dutheuil, Guillaume,Mahmood, Adeem,Aggarwal, Varinder K.
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p. 7491 - 7494
(2008/09/17)
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- Syntheses of novel chiral sulfinamido ligands and their applications in diethylzinc additions to aldehydes
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(Chemical Equation Presented) A novel class of sulfinamido alcohol ligands 1-6 was synthesized from (S)-tert-butanesulfinamide. These ligands showed excellent catalytic activities and enantiomeric selectivities in asymmetric additions of diethylzinc to aromatic aldehydes.
- Huang, Zhiyan,Lai, Hongshan,Qin, Yong
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p. 1373 - 1378
(2007/10/03)
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- Practical and highly enantioselective alkylation of aldehydes catalyzed by a titanium complex of 3-aryl H8-BINOL
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A titanium complex derived from 3-(3,5-diphenylphenyl)-H8-BINOL exhibits high catalytic activity and enantioselectivity in the alkylation of aldehydes. Enantioselectivities comparable to or higher than 20 mol % of the parent H8-BINOL
- Harada, Toshiro,Ukon, Takahiro
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p. 2499 - 2502
(2008/03/15)
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- Iterative stereospecific reagent-controlled homologation of pinacol boronates by enantioenriched α-chloroalkyllithium reagents
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Reaction of pinacol boronates with putative enantioenriched α-chloroalkyllithium species, generated in situ from homochiral α-chloroalkylsulfoxides by sulfoxide ligand exchange with t-BuLi in PhMe at -78 °C, gave chain-extended boronic ester products with generally excellent stereochemical fidelity. Iteration of this stereospecific reagent-controlled homologation (StReCH) process enabled the programmed synthesis of all four stereoisomers of a stereodiad-containing model system (4-benzyl-1,6-diphenylhexan-2-ol) with er ≥ 97:3 in all cases. Copyright
- Blakemore, Paul R.,Burge, Matthew S.
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p. 3068 - 3069
(2008/02/05)
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- New axially dissymmetric ligand recoverable with fluorous solvent
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Axially dissymmetric ligands with perfluoroalkyl groups, (Ra)-2,2′-bis[(R)-1-hydroxy-1H-perfluorooctyl]biphenyl [(Ra)-(R) 2-1c] and its enantiomer, have been synthesized successfully by the coupling reaction of the corresponding aryl bromide us
- Omote, Masaaki,Nishimura, Yuji,Sato, Kazuyuki,Ando, Akira,Kumadaki, Itsumaro
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p. 1886 - 1894
(2007/10/03)
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- Synthesis of chiral C/N-functionalized morpholine alcohols: Study of their catalytic ability as ligand in asymmetric diethylzinc addition to aldehyde
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A broad variety of chiral C/N-functionalized morpholine alcohols sharing a common structural motif in the 3-(hydroxymethyl)morpholine 6 were prepared from enantiomerically pure serine for the purpose of studying their catalytic ligand properties. The asym
- Dave, Rajesh,Sasaki, N. Andre
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p. 388 - 401
(2007/10/03)
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- De novo chiral amino alcohols in catalyzing asymmetric additions to aryl aldehydes
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A de novo structural class of chiral amino alcohol catalysts has been identified through a synergistic effort combining novel architectures from [4 + 3] cycloadditions and quantum mechanical interaction field predictions that closely match subsequent experimental measurements.
- Huang, Jian,Ianni, James C.,Antoline, Jennifer E.,Hsung, Richard P.,Kozlowski, Marisa C.
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p. 1565 - 1568
(2007/10/03)
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- 3,3′-diphosphoryl-1,1′-bi-2-naphthol-Zn(II) complexes as conjugate acid-base catalysts for enantioselective dialkylzinc addition to aldehydes
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A highly enantioselective dialkylzine (R22Zn) addition to a series of aromatic, aliphatic, and heteroaromatic aldehydes (5) was developed based on conjugate Lewis acid-Lewis base catalysis. Bifunctional BINOL ligands bearing phosphine oxides [P(=O)R2] (7), phosphonates [P(=O)(OR)2] (8 and 9), or phosphoramides [P(=O)(NR2) 2] (10) at the 3,3′-positions were prepared by using a phospho-Fries rearrangement as a key step. The coordination of a NaphO-Zn(II)-R2 center as a Lewis acid to a carbonyl group in a substrate and the activation of R22Zn(II) with a phosphoryl group (P=O) as a Lewis base in the 3,3′-diphosphoryl-BINOL- Zn(II) catalyst could promote carbon-carbon bond formation with high enantioselectivities (up to >99% ee). Mechanistic studies were performed by X-ray analyses of a free ligand (7) and a tetranuclear Zn(II) cluster (21), a 31P NMR experiment on Zn(II) complexes, an absence of nonlinear effect between the ligand (7) and Et-adduct of benzaldehyde, and stoichiometric reactions with some chiral or achiral Zn(II) complexes to propose a transition-state assembly including monomeric active intermediates.
- Hatano, Manabu,Miyamoto, Takashi,Ishihara, Kazuaki
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p. 6474 - 6484
(2007/10/03)
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- Immobilization of a BINOLate-titanium catalyst by use of aggregation phenomenon
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Upon treatment with titanium tetraisopropoxide, tris-BINOL with a rigid aromatic tether forms an insoluble polymeric aggregate, which shows a catalytic activity in asymmetric addition of diethylzinc to aldehydes. Georg Thieme Verlag Stuttgart.
- Harada, Toshiro,Nakatsugawa, Masashi
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p. 321 - 323
(2007/10/03)
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