- Regioselective and Stereoselective Heck-Matsuda Arylations of Trisubstituted Allylic Alkenols and Their Silyl and Methyl Ether Derivatives to Access Two Contiguous Stereogenic Centers: Expanding the Redox-Relay Process and Application in the Total Synthesis of meso-Hexestrol
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Novel palladium-catalyzed redox-relay Heck arylation reactions of trisubstituted allylic alkenols were developed employing silyl and methyl ethers. The reactions proceeded under mild conditions in moderate to high yields in an excellent anti diastereoselectivity to form α,β-disubstituted methyl ketones containing two contiguous stereocenters. The new redox-relay arylations using silyl and methyl ethers of the starting alkenols demonstrate that the presence of a free hydroxyl group is not a sine qua non condition for an effective redox-relay process as previously thought. Deuterium-labeled alkenols 2-d-10a, 2-d-10b, and 2-d-10c permitted tracking the palladium-hydride reinsertion steps in the conversion of the starting free alcohols, silyl, and methyl ethers into the corresponding methyl ketone 3-d-11a, with >98% deuterium retention. Moreover, the synthetic potential of the method was demonstrated with a straightforward synthesis of the meso-hexestrol in 4 steps, in 41% overall yield from alkenol 10a.
- Frota, Carlise,Polo, Ellen Christine,Esteves, Henrique,Correia, Carlos Roque Duarte
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p. 2198 - 2209
(2018/02/23)
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- ODOUR COMPOUNDS
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A compound of formula (I) wherein R1 and R2 are independently selected from hydrogen, methyl, ethyl, propyl and isopropyl; or R and R together form a saturated or monounsaturated 5- or 6-membered hydrocarbon ring, as represented by the arcuate dotted line; R3 is selected from methyl and ethyl; R4 is selected from methyl, ethyl, propyl, isopropyl, cyclopropyl, butyl, isobutyl, cyclobutyl and cyclopentyl; R5 is selected from hydrogen and methyl, and the dotted line between positions 3" and 4" represents an optional double bond. The compounds have a musk odour and are useful in fine and functional fragrances.
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Page/Page column 7-8
(2011/04/18)
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- The reaction of trialkylstannylmethyllithium with α,β-epoxy ketones and α-chloro ketones
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The reactions of trialkylstannylmethyllithium with α,β-epoxy ketones afforded mainly cyclopropanols, while α-chloro ketones afforded allyl alcohols and/or cyclopropanols, in varying amounts depending upon the molar ratio of the reagent to the substrate.
- Sato, Tadashi,Kikuchi, Toshihiro,Tsujita, Hiroshi,Kaetsu, Atsushi,Sootome, Norio,Nishida, Ken-Ichiro,Tachibana, Kazutaka,Murayama, Eigoro
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p. 3281 - 3304
(2007/10/02)
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- ACTION DES DIALKYLCUPRATES DE LITHIUM SUR LES ALDEHYDES α,β-ETHYLENIQUES
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Nearly exclusive 1-4 addition products are obtained by action of lithium dialkylcuprates with α,β-ethylenic aldehydes.Non polar solvents and low temperatures favor this reaction.Only α,β-ethylenic aldehydes having a trisubstituted double bond give a relatively important proportion of 1-2 addition product.
- Chuit, C.,Foulon, J. P.,Normant, J. F.
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p. 2305 - 2310
(2007/10/02)
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