- Low-valent Tantalum-mediated Reaction
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Treatment of a mixture of α-halogeno-esters and carbonyl compounds with low valent tantalum prepared readily from tantalum(V) chloride and activated zinc, afforded β-hydroxy esters in moderate to good yields.
- Aoyagi, Yutaka,Tanaka, Wataru,Ohta, Akihiro
-
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Read Online
- A Ball-Milling-Enabled Reformatsky Reaction
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An operationally simple one-jar one-step mechanochemical Reformatsky reaction using in situ generated organozinc intermediates under neat grinding conditions has been developed. Notable features of this reaction protocol are that it requires no solvent, no inert gases, and no pre-activation of the bulk zinc source. The developed process is demonstrated to have good substrate scope (39–82 % yield) and is effective irrespective of the initial morphology of the zinc source.
- Cao, Qun,Stark, Roderick T.,Fallis, Ian A.,Browne, Duncan L.
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p. 2554 - 2557
(2019/06/17)
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- Synthesis and Applications of Unquaternized C-Bound Boron Enolates
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A general and facile method to prepare unquaternized C-bound boron enolates by a ligand-controlled O-to-C isomerization is reported. Using this protocol, C-bound pinacolboron enolates have been isolated in pure form for the first time, and have been fully characterized by NMR spectroscopy and X-ray crystallography. In contrast to the general perception, such C-boron enolates are stable without coordinative saturation at the boron. Moreover, C-boron enolates present reactivities that are distinct from the O-boron enolates, and their applications in C-O and C-C bond formations are demonstrated.
- Ng, Elvis Wang Hei,Low, Kam-Hung,Chiu, Pauline
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supporting information
p. 3537 - 3541
(2018/03/21)
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- Scope and mechanism of the electrochemical Reformatsky reaction of α-haloesters on a graphite powder cathode in aqueous anolyte
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Six α-haloesters and eighteen carbonyl compounds were submitted to electrochemical coupling on a graphite powder cathode using aqueous anolyte free of organic solvents. Preparative yields of coupling products could be obtained with ethyl 2-bromoisobutyrate and aromatic aldehydes. Ethyl 2-bromopropionate was much less efficient. Extensive variation of applied potential, electrolyte composition, stoichiometry, catalyst, leaving halogen and activating substituents on the carbonyl compound led to the conclusion that the reaction mechanism in most cases proceeds via a radical intermediate generated from the halide reduction. Ethyl chloroacetate produced only trace amounts of coupling product, most probably by a carbanionic mechanism.
- De Souza, Carlos A.,Navarro, Marcelo,Bieber, Lothar W.,Areias, Madalena C.C.
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p. 118 - 126
(2014/05/06)
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- Access to enantiopure α-alkyl-β-hydroxy esters through dynamic kinetic resolutions employing purified/overexpressed alcohol dehydrogenases
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α-Alkyl-β-hydroxy esters were obtained via dynamic kinetic resolution (DKR) employing purified or crude E. coli overexpressed alcohol dehydrogenases (ADHs). ADH-A from R. ruber, CPADH from C. parapsilosis and TesADH from T. ethanolicus afforded syn-(2R,3S) derivatives with very high selectivities for sterically not impeded ketones ('small-bulky' substrates), while ADHs from S. yanoikuyae (SyADH) and Ralstonia sp. (RasADH) could also accept bulkier keto esters ('bulky-bulky' substrates). SyADH also provided preferentially syn-(2R,3S) isomers and RasADH showed in some cases good selectivity towards the formation of anti-(2S,3S) derivatives. With anti-Prelog ADHs such as LBADH from L. brevis or LKADH from L. kefir, syn-(2S,3R) alcohols were obtained with high conversions and diastereomeric excess in some cases, especially with LBADH. Furthermore, due to the thermodynamically favoured reduction of these substrates, it was possible to employ just a minimal excess of 2-propanol to obtain the final products with quantitative conversions. Copyright
- Cuetos, Anibal,Rioz-Martinez, Ana,Bisogno, Fabricio R.,Grischek, Barbara,Lavandera, Ivan,De Gonzalo, Gonzalo,Kroutil, Wolfgang,Gotor, Vicente
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supporting information; experimental part
p. 1743 - 1749
(2012/07/28)
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- Cp2ZrCl2-induced Reformatsky and Barbier reactions on isatins: An efficient synthesis of 3-substituted-3-hydroxyindolin-2-ones
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A mild and rapid one-pot process for Reformatsky and Barbier reactions using a catalytic quantity of zirconocene dichloride (Cp2ZrCl 2) as a promoter and zinc as a terminal reductant at room temperature in dimethyl formamide was developed. The protocol has wide substrate suitability and afforded the desired 3-substituted-3-hydroxyindolin-2-ones from istains in good yields and short reaction time.
- Chouhan, Mangilal,Sharma, Ratnesh,Nair, Vipin A.
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experimental part
p. 470 - 475
(2012/02/01)
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- Solvent-free synthesis of β-hydroxy esters and β-amino esters by indium-mediated reformatsky reaction
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In a convenient and efficient procedure for the solvent-free synthesis of β-hydroxy esters and β-amino esters, various aldehydes and aldimines undergo a Reformatsky reaction mediated by non-activated indium at room temperature to give the corresponding esters in good to excellent yields. Georg Thieme Verlag Stuttgart.
- Chen, Xi'an,Zhang, Changfu,Wu, Huayue,Yu, Xiaochun,Su, Weike,Cheng, Jiang
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p. 3233 - 3239
(2008/09/16)
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- An efficient cobalt(I)-catalysed reformatsky reaction using α-chloro esters
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An efficient cobalt(I)-catalysed Reformatsky reaction using α-chloro esters has been developed. The catalyst is prepared by reducing the cobalt(II) chloride (5%)/1,2-bis(diphenylphosphino)ethane (dppe)(5%)/zinc iodide (10%) system with zinc metal in acetonitrile in the presence of both the α-chloro ester and the carbonyl compound; good to excellent conversions to β-hydroxy esters are obtained at room temperature in 2.5 h.
- Lombardo, Marco,Gualandi, Alessandra,Pasi, Filippo,Trombini, Claudio
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p. 465 - 468
(2008/02/08)
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- Metal chloride-promoted aldol reaction of α-dimethylsilylesters with aldehydes, ketones, and α-enones
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In the presence of a catalytic amount of LiCl, α-dimethylsilylesters (α-DMS-esters) 1 smoothly reacted with various aldehydes at 30°C to give aldols in good to high yields. On the other hand, the aldol reaction with ketones was effectively promoted by MgCl2 rather than by LiCl. α-Enones also underwent the metal chloride-promoted addition of 1 at the carbonyl carbon or β-carbon. Georg Thieme Verlag Stuttgart.
- Miura, Katsukiyo,Nakagawa, Takahiro,Hosomi, Akira
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p. 1917 - 1921
(2007/10/03)
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- Catalytic generation of activated carboxylates: Direct, stereoselective synthesis β-hydroxyesters from epoxyaldehydes
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The catalytic generation of activated carboxylates from epoxyaldehydes enables the direct, stereoselective synthesis of β-hydroxyesters under mild, convenient reaction conditions. In addition to providing a new method for the synthesis of anti-aldol adducts, this chemistry unveils a mechanistically viable solution to the catalytic, waste-free synthesis of esters. Copyright
- Chow, Kenneth Yu-Kin,Bode, Jeffrey W.
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p. 8126 - 8127
(2007/10/03)
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- Dynamic kinetic resolution with enantioselective borohydride reduction catalyzed by optically active β-ketoiminato cobalt(II) complexes: Highly diastereo- and enantioselective preparation of optically active anti-aldol compounds
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Optically active anti-2-alkyl-3-hydroxy esters were stereo-selectively obtained from the corresponding 2-alkyl-3-keto esters using enantioselective borohydride reduction along with dynamic kinetic resolution in the presence of optically active β-ketoimina
- Ohtsuka, Yuhki,Miyazaki, Daichi,Ikeno, Taketo,Yamada, Tohru
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- Magnesium Bromide Mediated Highly Diastereoselective Heterogeneous Hydrogenation of Olefins
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(Matrix Presented) Palladium on carbon combined with magnesium bromide catalyzed hydrogenation of Baylis-Hillman olefins to afford the corresponding aldol derivatives in a highly syn-diastereoselective manner is described.
- Bouzide, Abderrahim
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p. 1347 - 1350
(2007/10/03)
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- Enantio- and diastereoselective reductive aldol reactions with iridium-pybox catalysts
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(formula presented) A catalytic amount of [(cod)IrCl]2 and indane-pybox converts diethylmethylsilane, methyl acrylate, and certain aldehydes to the derived reductive aldol adduct with good enantio- and diastereocontrol.
- Zhao, Cun-Xiang,Duffey, Matthew O.,Taylor, Steven J.,Morken, James P.
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p. 1829 - 1831
(2007/10/03)
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- Rhodium-catalyzed reformatsky-type reaction
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(equation presented) A novel Reformatsky-type reaction was developed using RhCl(PPh3)3 and diethylzinc. Inter- and intramolecular Reformatsky-type reactions were achieved efficiently under mild reaction conditions to give β-hydroxy esters.
- Kanai, Kazuo,Wakabayashi, Hitoshi,Honda, Toshio
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p. 2549 - 2551
(2007/10/03)
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- A facile preparation of indium enolates and their Reformatsky-and Darzens-type reactions
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Indium enolates were readily prepared by transmetalation of lithium enolates with indium trichloride, and were subsequently reacted with aldehydes to give β-hydroxy esters in high yields. Indium α-bromo enolates were also prepared and reacted with carbonyl compounds to give Darzens-type α,β-epoxy carbonyl products. The Royal Society of Chemistry 2000.
- Hirashita, Tsunehisa,Kinoshita, Kenji,Yamamura, Hatsuo,Kawai, Masao,Araki, Shuki
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p. 825 - 828
(2007/10/03)
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- Peroxycarbenium-mediated C-C bond formation: Applications to the synthesis of hydroperoxides and peroxides
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The Lewis acid-mediated reaction of alkene nucleophiles with peroxyacetals provides an effective route for the synthesis of homologated peroxides and hydroperoxides. In the presence of Lewis acids such as TiCl4, SnCl4, and trimethylsilyl triflate, peroxyacetals and peroxyketals undergo reaction with allyltrimethylsilane, silyl enol ethers, and silyl ketene acetals to afford homoallyl peroxides, 3-peroxyketones, and 3-peroxyalkanoates, respectively. Reactions of peroxyacetals are Lewis acid dependent; TiCl4 promotes formation of ethers while SnCl4 and trimethylsilyl triflate promote formation of peroxides. Lewis acid-promoted reactions of silylated hydroperoxyacetals furnish silylated hydroperoxides, which can be deprotected to homologated hydroperoxides. Hydroperoxyketals undergo Lewis acid-mediated allylation to furnish 1,2-dioxolanes via attack of hydroperoxide on the intermediate carbocation. Lewis acid-mediated cyclization of unsaturated peroxyacetals furnishes 1,2-dioxanes, 1,2-dioxepanes, and 1,2-dioxacanes through 6-endo/exo, 7-endo/endo, and 8-endo/endo pathways. The corresponding reactions involving 6-endo/endo and 5-endo/exo pathways were unsuccessful.
- Dussault,Lee, In Quen,Lee,Lee,Niu,Schultz,Zope
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p. 8407 - 8414
(2007/10/03)
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- Reversed stereochemical control in the presence of CeCl3 and TiCl4 in the Lewis acid mediated reduction of α-alkyl-β-keto esters by metal hydrides. A general methodology for the diastereoselective synthesis of syn- and anti-α-alkyl-β
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The Lewis acid-mediated reduction of α-alkyl-β-keto esters has been shown to proceed by different stereochemical control depending on the nature of the metal atom. Strongly chelating TiCl4 led to the syn isomer in high diastereomeric excess in
- Marcantoni, Enrico,Alessandrini, Sara,Malavolta, Marco,Bartoli, Giuseppe,Bellucci, Maria Cristina,Sambri, Letizia,Dalpozzo, Renato
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p. 1986 - 1992
(2007/10/03)
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- Conjugate addition of lithium enolates to aromatic carbonyl compounds complexed with aluminum tris(2, 6-diphenylphenoxide) (ATPH)
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Various lithium enolates of esters undergo effective 1, 6-addition to aromatic carbonyl compounds in the presence of aluminum tris(2, 6-diphenylphenoxide)(ATPH). Thieme.
- Saito, Susumu
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- Uncatalyzed aldol reaction using a dimethylsilyl enolate and α- dimethylsilyl ester in N,N-dimethylformamide
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Dimethylsilyl enolates and α-dimethylsilyl esters reacted with aldehydes in N,N-dimethyl-formamide without an activator to give aldol adducts in moderate to good yields. Under the same conditions, the corresponding trimethylsilyl derivatives exhibited lower reactivities toward the aldol reaction.
- Miura, Katsukiyo,Sato, Hiroshi,Tamaki, Kentaro,Ito, Hajime,Hosomi, Akira
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p. 2585 - 2588
(2007/10/03)
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- Chelation-controlled reduction of α- and β-oxygenated ketones with lithium tri-n-butylborohydride
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Lithium tri-n-butyl borohydride showed high selectivity in the reduction of α- and β-oxygenated ketones, giving a preponderance of the chelation controlled products.
- Faucher, Anne-Marie,Brochu, Christian,Landry, Serge R.,Duchesne, Isabelle,Hantos, Susanne,Roy, Amelie,Myles, Andrew,Legault, Claude
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p. 8425 - 8428
(2007/10/03)
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- Reformatsky Reaction in Water: Evidence for a Radical Chain Process
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The Reformatsky reaction of 2-bromo esters and carbonyl compounds in the presence of zinc can be carried out in concentrated aqueous salt solutions without any cosolvent. The reaction of bromoacetates is greatly enhanced by catalytic amounts of benzoyl peroxide or peracids and gives satisfactory yields with aromatic aldehydes. Preparative yields comparable to those of the traditional procedure are obtained with ethyl 2-bromoisobutyrate. This ester needs no catalyst and reacts even with saturated aldehydes and aromatic ketones, although in low yields. A radical chain mechanism, initiated by electron abstraction from the organometallic Reformatsky reagent, is proposed. Two nonchain pathways, involving radicals directly produced on the metal surface, may compete, especially in the case of secondary and tertiary halides.
- Bieber, Lothar W.,Malvestiti, Ivani,Storch, Elisabeth C.
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p. 9061 - 9064
(2007/10/03)
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- Surface-mediated solid phase reaction. Part 9. A convenient procedure for aldol reaction of ketene silyl acetals with aldehydes on the solid surface of alumina
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The aldol reaction of ketene silyl acetals with aldehydes proceeds efficiently on the solid surface of alumina impregnated with anhydrous zinc chloride under sonication providing aldol products in high yields and with good stereoselectivity.
- Ranu, Brindaban C.,Saha, Manika,Bhar, Sanjay
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p. 3065 - 3077
(2007/10/03)
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- A highly diastereoselective synthesis of α-substituted-β-hydroxy compounds from corresponding β-stannyl compounds
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Anti- β -stannyl- α -substituted carbonyl compounds were completely converted to its syn-analogues, and each diastereomer was oxidized to its β -hydroxylated analogues with retention of the stereochemistry.
- Yamamoto, Makoto,Itoh, Kiyoshi,Kishikawa, Keiki,Kohmoto, Shigeo
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p. 1035 - 1036
(2007/10/03)
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- Samarium(II) triflate as a new reagent for the grignard-type carbonyl addition reaction
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On treatment of a THF solution of Sm(OTf)3 with 1 equiv of an organolithium or organomagnesium reagent at ambient temperature, the purple or deep green solution of the divalent samarium triflate [Sm(OTf)2] was readily obtained. For this preparation, s-BuLi was the most effective as was evidenced by the reduction of 2-phenylethyl iodide in the presence of HMPA. The Sm(OTf)2 reagent mediated the Grignard-type reaction effectively in THF/HMPA; alkylation and allylation of ketones or aldehydes with alkyl, allyl, or benzyl halides proceeded via organosamarium intermediates. Diastereoselectivity of the samarium-Grignard reaction was examined using 2-methylcyclohexanone, 4-tert-butylcyclohexanone, and 2-phenylpropanal and was found to be higher in each case than that with SmI2. With 2-methylcyclohexanone, for example, Sm(OTf)2 gave the greatest ratio of axial alcohol:equatorial alcohol = 99:1, and SmI2 gave a ratio of 91:9. Halides containing an ester or a silyl group were reactive in the Reformatsky- or Peterson-type reaction, respectively, using the Sm(OTf)2 reagent.
- Fukuzawa, Shin-Ichi,Mutoh, Keisuke,Tsuchimoto, Teruhisa,Hiyama, Tamejiro
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p. 5400 - 5405
(2007/10/03)
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- Preparation of manganous enolates and its applications
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A method of preparing manganous enolates by the treatment of alkali metal or alkaline earth metal enolates with manganous compounds in a solvent for the Mn enolate to be prepared.
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- Bifunctional chiral auxiliaries 7: Aldol reactions of enolates derived from 1,3-diacylimidazolidine-2-thiones and 1,3-diacylimidazolidin-2-ones
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Dibutylboron enolates of 1,3-diacylimidazolidine-2-thiones and 1,3-diacylimidazolidin-2-ones undergo highly syn-stereoselective aldol reactions with aldehydes to allow elaboration of both acyl sidechains. The reaction is proposed to occur via sequential e
- Davies,Edwards,Evans,Mortlock
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p. 6621 - 6642
(2007/10/02)
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- Enolboration. 6. Dicyclohexyliodoborane, a Versatile Reagent for the Stereoselective Synthesis of Either Z or E Enolates from Representative Esters
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A smooth, rapid, quantitative, and highly stereoselective synthesis of either Z or E enolates from representative esters has been achieved with dicyclohexyliodoborane, Chx2BI, in the presence of a suitable tertiary amine, such as triethylamine or N,N-diis
- Ganesan, Kumaraperumal,Brown, Herbert C.
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p. 2336 - 2340
(2007/10/02)
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- Stereoselective reduction of 2-methyl-3-oxo esters (or amides) with sodium borohydride catalyzed by manganese (II) chloride or tetrabutylammonium borohydride. A practical preparation of erythro and threo-3-hydroxy-2-methyl esters (or amides)
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erythro-3-Hydroxy-2-methylpropionates or erythro-3-hydroxy-2-methylpropionamides were prepared with high stereoselectivity by NaBH4 reduction of the corresponding 2-methyl-3-oxo esters or 2-methyl-3-oxo amides in the presence of a catalytic amount of manganese(II) chloride. On the other hand, reduction of these substrates with n-Bu4NBH4 provided threo-isomers selectively. erythro-Selective reduction of 2-methyl-3-oxo amides with NaBH3CN in 1N HCl-MeOH is also described.
- Taniguchi, Masahiko,Fujii, Hideaki,Oshima, Koichiro,Utimoto, Kiitiro
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p. 11169 - 11182
(2007/10/02)
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- Lithium Benzenetellurolate-induced Reformatsky-type Reaction in the Presence of Cerium Trichloride
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Reformatsky-type reactions with PhTeLi in the presence of CeCl3 proceeded smoothly under mild conditions.The PhTeLi-CeCl3 reagent was particularly efficient for the reactions of sterically hindered and enolizable ketones; in the absence of CeCl3 unsatisfactory yields of the desired β-hydroxy ketone were obtained.It is assumed that CeCl3 reactions involve a cerium enolate intermediate.The stereoselectivity of the reaction between ethyl 2-bromopropionate and benzaldehyde is also described.
- Fukuzawa, Shin-ichi,Hirai, Katsuhiko
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p. 1963 - 1966
(2007/10/02)
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- Catalytic Asymmetric Aldol-Type Reactions Using a Chiral (Acyloxy)borane Complex
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In the presence of 20 molpercent of a chiral (acyloxy)borane (CAB) complex prepared from BH3*THF and a chiral mono-O-acylated tartaric acid, achiral silyl enol ethers or ketene silyl acetals react with achiral aldehydes to afford the corresponding aldol-t
- Ishihara, Kazuaki,Maruyama, Tohru,Mouri, Makoto,Gao, Qingzhi,Furuta,Kyoji,Yamamoto, Hisashi
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p. 3483 - 3491
(2007/10/02)
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- Investigation of a Model for 1,2-Asymmetric Induction in Reactions of α-Carbalkoxy Radicals: A Stereochemical Comparison of Reactions of α-Carbalkoxy Radicals and Ester Enolates
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The stereochemical course of reductions and allylations of α-carbalkoxy radicals with chiral centers at the β-position are reported.Radicals without polar substituents, with alkoxyl or acetoxyl groups, and with hydroxyl groups at the β-position were exami
- Hart, David J.,Krishnamurthy, Ramanarayanan
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p. 4457 - 4470
(2007/10/02)
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- One-pot Preparation of β-Hydroxy Esters Catalysed by a Bis(cyclopentadienyl)titanium(IV) Dichloride-Zinc System
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The reaction of α-haloesters with carbonyl compounds catalysed by Cp2TiCl2(cat.)-Zn gives β-hydroxy esters.
- Ding, Yu,Zhao, Gang
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p. 941 - 942
(2007/10/02)
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- A PRACTICAL AND STEREOSELECTIVE REDUCTION OF 3-KETO-2-METHYL ESTERS OR 3-KETO-2-METHYL AMIDES INTO ERYTHRO-3-HYDROXY-2-METHYL ESTERS OR ERYTHRO-3-HYDROXY-2-METHYL AMIDES WITH NaBH4 CATALYZED BY MnCl2
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Erythro-3-hydroxy-2-methylpropionates or erythro-3-hydroxy-2-methylpropionamides were prepared with high stereoselectivity by NaBH4 reduction of the corresponding 3-keto esters or 3-keto amides in the presence of a catalytic amount of MnCl2.
- Fujii, Hideaki,Oshima, Koichiro,Utimoto, Kiitiro
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p. 6147 - 6150
(2007/10/02)
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- ACTIVATION OF KETENE SILYL ACETALS BY 10-METHYLACRIDINIUM PERCHLORATE: A NOVEL CATALYSIS IN MUKAIYAMA REACTION
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10-Methylacridinium perchlorate (1) effectively promotes various reactions of ketene silyl acetals: aldol and Michael addition products are obtained with aldehydes, ketones, acetals, and α-enones.The reactions exhibit unusual dependency upon 1, namely the yields are excellent when a catalytic amount of 1 is employed whereas no desired products are accessible by the use of 1 in a stoichiometric quantity.A novel catalytic cycle is proposed.
- Otera, Junzo,Wakahara, Yoshiyuki,Kamei, Hidenobu,Sato, Tsuneo,Nozaki, Hitosi,Fukuzumi, Shunichi
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p. 2405 - 2408
(2007/10/02)
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- Diastereoselective aldol condensation of directly generated titanium enolates of activated esters
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Simply generated (TiCl4, Et3N, -78°C) titanium enolates of some thioesters and α-thio substituted esters undergo aldol condensations with achiral and chiral aldehydes with low to high stereoselectivity. An 1H-NMR study of
- Annunziata, Rita,Cinquini, Mauro,Cozzi, Franco,Cozzi, Pier Giorgio,Consolandi, Emanuela
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p. 7897 - 7910
(2007/10/02)
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- REFORMATSKY REACTION USING Zn/Ag COUPLE
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The Reformatsky reaction is easy to run in ethereal solvents in the presence of Zn/Ag couple.From methyl γ-bromocrotonate and krtones, remified esters are fromed in refluxing Et2O, linear ones in refluxing THF.
- Bortolussi, Michel,Seyden-Penne, Jacqueline
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p. 2355 - 2362
(2007/10/02)
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- Reactivity of α-Metal(group 4) Esters. Lewis Acid Mediated Reactions of α-Triphenyltin Esters with Aldehydes and Acetals
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Ethyl triphenylstannylacetate and ethyl α-triphenylstannylpropionate reacted with aldehydes and acetals to give β-hydroxy and β-alkoxy esters at room temperature in the presence of TiCl4 in moderate yields.Under these conditions ethyl triphenylgermylacetate and ethyl trimethylsilylacetate did not work.
- Kiyooka, Syun-ichi,Nakata, Masumi
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p. 721 - 722
(2007/10/02)
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- IMPROVED ENANTIOSELECTIVE SYNTHESIS OF ANTI α-METHYL-β-HYDROXYESTERS THROUGH TiCl4-PPh3 MEDIATED ALDOL CONDENSATION
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The complex between TiCl4 and PPh3 effectively catalyses the aldol addition of silyl ketene acetals to aldehydes dramatically improving the anti-syn ratios.
- Palazzi, Camillo,Colombo, Lino,Gennari, Cesare
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p. 1735 - 1738
(2007/10/02)
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- Effective Kinetic Resolution in the Asymmetric Hydrogenation of α-(Hydroxyalkyl)acrylate Esters
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The title compounds are reduced by H2 and biphosphine-rhodium catalysts with high anti-selectivity; asymmetric catalysts gave up to 7:1 discrimination between the enantiomers of starting material.
- Brown, John M.,Cutting, Ian
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p. 578 - 579
(2007/10/02)
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- SYNTHETIC CONTROL LEADING TO CHIRAL COMPOUNDS
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A highly diastereoselective cross aldol reaction is developed using divalent tin enolates formed from stannous trifluoromethanesulfonate and carbonyl compounds.The reaction is extended to a highly enantioselective cross aldol reaction employing chiral dia
- Mukaiyama, Teruaki,Iwasawa, Nobuharu,Stevens, Rodney W.,Haga, Toru
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p. 1381 - 1390
(2007/10/02)
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- ALDOL REACTIONS, CONJUGATE ADDITIONS, AND ALKYLATION REACTIONS OF O-SILYLATED KETENE ACETALS UNDER NEUTRAL CONDITIONS
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Aldol reactions, conjugate additions, and alkylation reactions of O-silylated ketene acetals take place under neutral conditions by using a high pressure technique.
- Yamamoto, Yoshinori,Maruyama, Kazuhiro,Matsumoto, Kiyoshi
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p. 1075 - 1078
(2007/10/02)
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- Carbon-Carbon Bond-Forming Reactions Using Cerium Metal or Organocerium(III) Reagents
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Carbon-carbon bond-forming reactions using cerium metal or organocerium(III) reagents have been investigated.Cerium amalgam is an effective reagent for the chemoselective preparation of homoallylic alcohols from allyl halides and carbonyl compounds.These same reagent can also be satisfactorily employed for the Reformatsky-type reaction of α-halo esters with carbonyl compounds.It has been shown that organocerium(III) reagents are conveniently generated by the reaction of organolithiums with cerium(III)iodide or cerium(III)chloride.The reagents are less basic thanorganolithiums or Grignard reagents, and they react cleanly at -78 to -65 deg C with various carbonyl compounds to afford the addition products in high yields, even though the substrates are susceptible to enolization or metal-halogen exchange with simple organolithiums.The same reagents react also with α,β-unsaturated compounds to yield 1,2-addition products in high selectivity.
- Imamoto, Tsuneo,Kusumoto, Tetsuo,Tawarayama, Yoshinori,Sugiura, Yasushi,Mita, Takeshi,et al.
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p. 3904 - 3912
(2007/10/02)
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- Photoreduction of 2-Benzoylalkanoates
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2-Benzoylalkanoates 1 undergo photoreduction with 2-propanol.The photoreduction products are classified into three types according to their origin: the homo-pinacol-type products 2, 5, 7, and 8, the mixed-pinacol-type product 3, and the β-hydroxy ester 6.
- Yoshioka, Michikazu,Aoki, Satoshi,Shimizu, Toshio,Hasegawa, Tadashi
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p. 2230 - 2233
(2007/10/02)
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- A NEW METHOD FOR THE SYNTHESIS OF β-HYDROXYESTERS BY USING METALLIC TIN
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Metallic tin or activated metallic tin, prepared by reduction of stannous chloride with lithium aluminum hydride, smoothly reacts with α-haloesters to yield tin enolates, which in turn react with carbonyl compounds under mild conditions to give, after hydrolysis, β-hydroxyesters in high yields.
- Harada, Taira,Mukaiyama, Teruaki
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p. 161 - 164
(2007/10/02)
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- STANNOUS TRIFLATE MEDIATED ALDOL REACTION OF 3-ACYLTHIAZOLIDINE-2-THIONE: A CONVENIENT METHOD FOR THE STEREOSELECTIVE SYNTHESIS OF β-HYDROXY ALDEHYDE AND β-HYDROXY CARBOXYLIC ACID DERIVATIVES
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Divalent tin enolates, formed from stannous triflate and 3-acylthiazolidine-2-thiones, react with aldehydes with erythro-selectivities.The adducts are easily transformed into β-hydroxy aldehyde and β-hydroxy carboxylic acid derivatives.
- Mukaiyama, Teruaki,Iwasawa, Nobuharu
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p. 1903 - 1906
(2007/10/02)
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