- Mukaiyama aldolisation reactions of α,β-epoxyaldehydes in aqueous media
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The Mukaiyama aldolisation reaction in aqueous media of cis and trans α,β-epoxyaldehydes with tert-butyldimethylsilyl ketene acetal in the presence of Lewis's acids was studied. Sc(OTf)3 gave the best results in terms of selectivity. The same r
- Ruland, Yvan,Noereuil, Pierre,Baltas, Michel
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- Synthesis of Phostones via the Palladium-Catalyzed Ring Opening of Epoxy Vinyl Phosphonates
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The reaction of epoxy aldehydes with tetraethyl methylenediphosphonate gave γ,δ-epoxy vinyl phosphonates. The palladium-catalyzed addition of primary alcohols gave the monoprotected diols as single diastereoisomers. The trans- and cis-epoxides lead to opp
- Gnawali, Giri Raj,Rath, Nigam P.,Spilling, Christopher D.
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p. 8724 - 8730
(2019/07/03)
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- Palladium-catalyzed stereospecific epoxide-opening reaction of γ,δ-epoxy-α,β-unsaturated esters with an alkylboronic acid leading to γ,δ-vicinal diols with double inversion of the configuration
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A palladium-catalyzed stereospecific epoxide-opening reaction of γ,δ-epoxy-α,β-unsaturated esters with an alkylboronic acid leading to γ,δ-vicinal diols is described, which proceeds with retention of the configuration, i.e., via two consecutive SN/s
- Hirai, Atsushi,Yu, Xiao-Qiang,Tonooka, Terumichi,Miyashita, Masaaki
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p. 2482 - 2483
(2007/10/03)
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- A study on the chelation control in the regioselective opening of 2,3-bifunctionalized epoxides
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The results obtained in the MgBr2-mediated opening of 2,3-bifunctionalized epoxides are reported. The studies showed that the chelation control of MgBr2 between different functionalities can in some cases be selective.
- Righi, Giuliana,Pescatore, Giovanna,Bonadies, Francesco,Bonini, Carlo
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p. 5649 - 5656
(2007/10/03)
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- Aminolysis of vinyl epoxides as an efficient entry to N-H vinylaziridines
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Vinyl epoxides 8a-f 11 and 12 have been prepared from the corresponding epoxy alcohols while 8g was formed by a regioselective epoxidation of the parent diene. Aminolysis of these materials resulted in a regio- and stereoselective nucleophilic opening at C3 in good yields except for the sterically hindered substrates. The trans-oxiranes gave the anti-amino alcohols while the cis derivative 12 gave the syn isomer 17. Cyclization of the anti-amino alcohols was best effected using the Mitsunobu protocol giving the corresponding N-H vinylaziridines in 50-54% yields, while the syn-amino alcohol 17 was transformed into the cis-vinylaziridine 31 with chlorosulfonic acid followed by base treatment in 20% yield. The outcome of these cyclizations seems to indicate that they are controlled by subtle steric effects in the substrate. The N-H vinylaziridine 24 was alkylated with tert-butyl bromoacetate and the product subjected to an aza[2,3]-Wittig rearrangement to give tetrahydropyridine 30 while acetylation of 24 followed by base treatment resulted in an aza-[3,3]-Claisen rearrangement yielding the seven-membered lactam 32.
- Lindstroem, Ulf M.,Somfai, Peter
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p. 109 - 117
(2007/10/03)
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- HIGHLY REGIOSELECTIVE PALLADIUM-MEDIATED SUBSTITUTION OF ALLYLIC AND DIENYLIC CYCLIC CARBONATES
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Reaction of chiral allylic and dienylic cyclic carbonates with various nucleophiles in the presence of (PPh3)4Pd as a catalyst afforded α-, γ-, or ε-substituted products with high regio-, (E)-stereo-, and diastereoselectivity depending on nucleophiles.
- Kang, Suk-Ku,Park, Dong-Chul,Jeon, Jae-Ho,Rho, Ho-Sik,Yu, Chan-Mo
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p. 2357 - 2360
(2007/10/02)
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- Reductive Cleavage Reaction of γ-Functionalized α,β-Unsaturated Esters and Halomethyls Mediated with Magnesium in Methanol
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Reductive cleavage of various types of C-O and C-N bonds tethered to α,β-unsaturated esters and halomethyls was mediated with magnesium in methanol, which provided a facile method for the synthesis of δ-hydroxy or δ-amino β,γ-unsaturated esters and allylic alcohols.Regardless of the geometry (E or Z) of the α,β-unsaturated esters, 1a-b, 5a-c, 11, 13, and 23, the cleavage product obtained was exclusively the E isomer of the corresponding deconjugated hydroxy and amino esters.The steric bias and ring strain of 15, 17, and 21 gave rise to a product mixture of E and Z isomers.
- Pak, Chwang Siek,Lee, Eun,Lee, Ge Hyeong
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p. 1523 - 1530
(2007/10/02)
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