- 3,3′-Bithiophene-Based Chiral Bisphosphine Oxides as Organocatalysts in Silicon-Derived Lewis Acid Mediated Reactions
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This account summarizes the development of new biheteroaromatic chiral bisphosphine oxides. 3,3′-Bithiophene-based phosphine oxides (BITIOPOs) have been successfully used as organocatalysts to promote Lewis base catalyzed, Lewis acid mediated stereoselective transformations. These highly electron-rich compounds, in combination with trichorosilyl derivatives (allyltrichlorosilane and silicon tetrachloride), generate hypervalent silicon species that act as chiral Lewis acids in highly diastereo- and enantioselective organic reactions. Several relevant examples related to these applications are discussed in detail. 1 Introduction 2 The BITIOPO Family 3 Enantioselective Opening of Epoxides 4 Enantioselective Allylation of Aldehydes 5 Stereoselective Direct (Double) Aldol-Type Reaction with Ketones 6 Stereoselective Direct Aldol-Type Reaction with Ester Derivatives 7 Conclusions.
- Benaglia, Maurizio,Benincori, Tiziana,Raimondi, Laura Maria,Rossi, Sergio
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p. 535 - 546
(2020/03/27)
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- Enantio- and diastereoselective synthesis of (E)-1,5-syn-diols: Application to the synthesis of the C(23)-C(40) fragment of tetrafibricin
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A highly stereoselective synthesis of (E)-1,5-syn-diols 6 is described. The kinetically controlled hydroboration of allenyltrifluoroborate 8 with Soderquist borane 2 provides the (Z)-allylic trifluoroborate 9, which undergoes sequential allylboration with two different aldehydes to provide (E)-1,5-syn-diols 6 in 72-98% yields with >95% ee and >20:1 dr. Application of this method to the synthesis of the tetrafibricin C(23)-C(40) fragment 19 is described.
- Kister, Jeremy,Nuhant, Philippe,Lira, Ricardo,Sorg, Achim,Roush, William R.
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supporting information; experimental part
p. 1868 - 1871
(2011/06/22)
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- Diastereo- and enantioselective anti-alkoxyallylation employing allylic gem-dicarboxylates as allyl donors via iridium-catalyzed transfer hydrogenation
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(Chemical Equation Presented) Enantioselective transfer hydrogenation of gem-dibenzoate 1e in the presence of aromatic, α,β-unsaturated, or aliphatic aldehydes 2a-i mediated by isopropyl alcohol and employing a cyclometalated iridium C,O-benzoate derived from allyl acetate, 4-cyano-3-nitrobenzoic acid, and (R)-SEGPHOS delivers products of alkoxyallylation 3a-i, 4a, 4e, 4f, and 4i in good isolated yields (62-82%) with good to excellent diastereoselectivities (7:1 to 18:1 dr) and exceptional enantioselectivities (90-99% ee). This protocol provides an alternative to the use of premetalated nucleophiles in carbonyl alkoxyallylation. Copyright
- Han, Soo Bong,Han, Hoon,Krische, Michael J.
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supporting information; experimental part
p. 1760 - 1761
(2010/04/25)
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- 3-bromozinc propenyl esters: An experimental and theoretical study of the unique stereocrossover observed in their addition to aromatic and aliphatic aldehydes
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(Chemical Equation Presented) We report the results of a combined experimental and theoretical study on the reaction of 3-bromopropenyl acetate in the presence of zinc with three different aldehydes (i.e., benzaldehyde, 2-methylpropanal, and cyclohexaneca
- Bottoni,Lombardo,Miscione,Pujol Algue,Trombini
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p. 418 - 426
(2008/09/17)
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- Synthesis of homoallylic chiral tertiary alcohols via chelation-controlled diastereoselective nucleophilic addition on α-alkoxyketones: Application for the synthesis of the C1-C11 subunit of 8-epi-fostriecin
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(Matrix presented) Chiral β-syn-alkoxyhomoallylic alcohols derived from alkoxyallylboration of aldehydes upon oxidation provided the corresponding chiral ketones. Chelation-controlled nucleophilic addition to these ketones occurred in a highly stereoselec
- Ramachandran, P. Veeraraghavan,Liu, Haipeng,Reddy, M. Venkat Ram,Brown, Herbert C.
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p. 3755 - 3757
(2007/10/03)
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- Stereoselective syntheses of (+)-goniodiol, (-)-8-epigoniodiol, and (+)-9-deoxygoniopypyrone via alkoxyallylboration and ring-closing metathesis
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A convenient synthesis of (+)-goniodiol, (-)-8-epigoniodiol, and (+)-9-deoxygoniopypyrone has been developed via asymmetric alkoxyallylboration and ring-closing metathesis pathways.
- Ramachandran, P. Veeraraghavan,Chandra, J. Subash,Reddy, M. Venkat Ram
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p. 7547 - 7550
(2007/10/03)
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- A new protocol for the acetoxyallylation of aldehydes mediated by indium in THF
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matrix presented A new precursor of a formal 1-hydroxy allyl anion is represented by 3-bromo-1-acetoxy-1-propene, which is synthesized by the ZnCl2-catalyzed addition of acetyl bromide to propenal. 3-Bromo-1-acetoxy-1-propene reacts with indium
- Lombardo, Marco,Girotti, Rugiada,Morganti, Stefano,Trombini, Claudio
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p. 2981 - 2983
(2007/10/03)
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- Synthetic Studies on Calyculin A: A Convenient Asymmetric Synthesis of anti-Vicinal Diols
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anti-Vicinal diols have been prepared with excellent relative and absolute stereocontrol via the reaction of aldehydes with B-allyl>diisopinocampheylborane in THF and diethyl ether and work-up using potassium fluoride,
- Barrett, Anthony G. M.,Malecha, James W.
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p. 1901 - 1906
(2007/10/02)
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- Enantioselective allyltitanation of aldehydes with cyclopentadienylialkoxyallylitanium complexes
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The preparation, analysis, and reactions of novel, highly stereoselective cyclopentadienyldialkoxyallyltitanium reagents, available in both enamiomeric forms, are described. Chiral monochlorotitanates are readily prepared from CpTiCl3 or Cp*TiC
- Hafner, Andreas,Duthaler, Rudolf O.,Marti, Roger,Rihs, Grety,Rothe-Streit, Petra,Schwarzenbach, Franz
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p. 2321 - 2336
(2007/10/02)
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- B-diisopinocampheylborane: An Excellent Reagent for the Stereoselective Synthesis of Anti Vicinal Diols
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Aldehydes reacted stereoselectively with B-diisopinocampheylborane, derived from (+)- and (-)-α-pinene, to provide, on workup with hydrogen peroxide, (3S,4R)- and (3R,4S)-dihydroxy-1-alkenes, respectively.
- Barrett, Anthony G. M.,Malecha, James W.
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p. 5243 - 5245
(2007/10/02)
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- Metalated Allylaminosilane: A New, Practical Reagent for the Stereoselective α-Hydroxyallylation of Aldehydes to Erythro-1,2-diol Skeletons
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A zinc reagent derived from allyl(diisopropylamino)dimethylsilane reacts with aldehydes regio- and stereoselectively to form erythro-3-silyl-1-alken-4-ols, which are further transformed into erythro-1-alkene-3,4-diols by hydrogen peroxide oxidation of the
- Tamao, Kohei,Nakajo, Eiji,Ito, Yoshihiko
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p. 957 - 958
(2007/10/02)
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- Regiochemical Convergence in the Reaction of Heterosubstituted Allylic Carbanions via Allylic Aluminum and Boron "Ate" Complexes
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The regiochemistry in reactions of heterosubstituted allylic carbanions (1) is highly controlled via allylic aluminum or boron "ate" complexes which direct both carbonyl compounds and reactive halides to the α-position with high regioselectivity.For example, carbonyl compounds react with the oxygen- (3), sulfur- (12), selenium- (20), and silicon- (25) substituted allylic carbanions at the α-position via the ate complexes.Although the reactions of the ate complexes (2) with aldehydes generally produce a mixture of erythro and threo isomers, the aluminum ate comlex of 3b gives the erythro isomer (5) with very high stereoselectivity.This procedure is applied to the stereoselective synthesis of exo-brevicomin (9).With allylic halides, the oxygen- (3a) and sulfur- (12) substituted allylic carbanions again react at the α-position via the ate complexes.However, the coupling mode is entirely different; the α-α' coupling product (10) is obtained from 3a, while the α-γ' coupling product (15) is produced from 12.
- Yamamoto, Yoshinori,Yatagai, Hidetaka,Saito, Yoshikazu,Maruyama, Kazuhiro
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p. 1096 - 1104
(2007/10/02)
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- Stereoselective Acyclic Synthesis via Allylmetals: Vicinal Diols from γ-Alkoxyallylaluminium Compounds and Aldehydes or Ketones
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The reaction of in situ generated γ-alkoxyallylaluminium compounds with aldehydes or ketones at -78 deg C leads to the highly diastereoselective formation of mono-protected vicinal diols; the precursor to exo-brevicomin was efficiently synthesised using t
- Koreeda, Masato,Tanaka, Yoshio
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p. 845 - 847
(2007/10/02)
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