- Synthesis of (E)-1-Propenyl Ketones from Carboxylic Esters and Carboxamides by Use of Mixed Organolithium-Magnesium Reagents
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The novel reagents formed by combination of allylmagnesium chloride and a strong non-nucleophilic lithium base (LiNR2) convert non- or slowly enolizable carboxylic esters or carboxamides into 2-propenyl ketones which are protected from further reaction by their in situ conversion into enolates.This modified Grignard reaction is applied to efficient syntheses of α-damascone, β-damascone, β-damascenone, and various other (E)-1-propenyl ketones.
- Fehr, Charles,Galindo, Jose
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- Synthesis of chlorins and bacteriochlorins from cycloaddition reactions with porphyrins
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Chlorins and bacteriochlorins are reduced porphyrin-type derivatives displaying characteristic structural, physical, and chemical features. Such features make chlorins and bacteriochlorins key “players” in several fields, and specifically in medicine as p
- Cavaleiro, José A. S.,Monteiro, Carlos J. P.,Moura, Nuno M. M.,P. M. S. Neves, M. Gra?a,Tomé, Augusto C.
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- Synthesis method of beta-damascenone
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The invention provides a synthesis method of beta-damascenone. The synthesis method comprises the following steps: 1) carrying out nucleophilic addition reaction on a compound II and acetylene to generate a compound III; (2) carrying out condensation reaction on the compound III and acetaldehyde to generate a compound IV, and (3) carrying out Meyer-Schureter rearrangement reaction on the compoundIV to obtain a compound V, namely the beta-damascenone.
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- DIASTEREOCONTROLLED SYNTHESIS OF FUNCTIONALIZED TRANS-DECALINS VIA ELECTROCYCLIC REACTION OF TRIENOL ETHERS
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(E)-Trienol silyl ethers 10 and 11, selectively prepared by mono-Grignard reaction on methyl β-cyclogeranate (7) or by deprotonation of enone 8 were transformed to trans-decalins 5 and 6 by a thermal electrocyclic reaction.The hithero unknown enones 5 and 6 exhibit interesting organoleptic properties and show promise as versatile synthetic intermediates.The herein described transformation opens a new route for the direct construction of C(6)-functionalized drimanes such as cinnamodial (3) and forskolin (4).
- Fehr, Charles,Galindo, Jose,Guntern, Olivier
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p. 4021 - 4024
(2007/10/02)
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- 172. β-Cleavage of Bis(homoallylic) Potassium Alkoxides. Two-Step Preparation of Propenyl Ketones from Carboxylic Esters. Synthesis of ar-Turmerone, α-Damascone, β-Damascone, and β-Damascenone
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The transformation of 36 bis(homoallylic) alcohols VII to alkenones IX and X via β-cleavage of their potassium alkoxides VIIa in HMPA has been investigated (cf.Scheme 2).These studies have established an order of β-cleavage for 2-propenyl, 1-methyl-2-propenyl, 2-methyl-2-propenyl, 1,1-dimethyl-2-propenyl, and benzyl groups in alkoxides 49a-56a and have allowed a comparison between the β-cleavage reaction and the oxy-Cope rearrangement in alkoxides 74a-83a.As illustrative synthetic applications, a two-step preparation of propenyl ketones 15-42 from carboxylic esters is described, together with syntheses of ar-turmerone (48), α-damascone ((E)-71), β-damascone ((E)-109), and β-damascenone ((E)-111).
- Snowden, Roger L.,Linder, Simon M.,Muller, Bernard L.,Schulte, Karl H.
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p. 1858 - 1878
(2007/10/02)
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- An Improved Two-step Route for the Preparation of β-Diketones from Aldehydes and its Application to the Synthesis of β-Damascone
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α-Diazo-β-hydroxyketones, obtained by condensation of aldehydes with 1-diazo-1-lithioacetone, are efficiently transformed into the corresponding β-diketones by exposure to rhodium(II) acetate, The sequence is applied to a new synthesis of β-damascone (10).
- Pellicciari, Roberto,Fringuelli, Renata,Sisani, Ettore,Curini, Massimo
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p. 2566 - 2569
(2007/10/02)
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- A NEW SYNTHESIS OF β-DAMASCONE
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A new synthetic route to β-damascone (7) starting from β-cyclocitral is described.The crucial intermediate 9-oxo-dihydro-β-damascone (3) is prepared in two steps by treatment of (1) with 1-diazo-1-lithioacetone followed by the rhodium (II) acetate conversion of 3-diazo-4-hydroxy-4(2,2,6-trimetylcyclohex-6-enyl) butan-2-one (2) thus formed to (3).
- Pellicciari, Roberto,Sisani, Ettore,Fringuelli, Renata
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p. 4039 - 4042
(2007/10/02)
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- Alkenoyl-cyclohexadienes
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New cycloaliphatic unsaturated ketones and their use as perfuming and odour-modifying agents in the manufacture of perfumes and perfumed products, and as flavouring and taste-modifying agents in the preparation of foodstuffs in general and imitation flavours for foodstuffs, beverages, animal feeds, pharmaceutical preparations and tobacco products. Methods for the preparation of said cycloaliphatic unsaturated ketones.
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- 147. Model reactions for the biosynthesis of damascone-related compounds and their preparative application
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We report a new general synthesis of damasconcs. In the presence of acids, 7, 8-dehydro-β-ionole (10) or the related diols 11 are converted into a mixture of β-damascone (2) and the 7, 8-dehydrotheaspiranes (19). In the same way the 6-hydroxy-7, 8-dehydro-α-ionoles 12 are transformed into a mixture of β-damascenone (3) and the 8-oxatheaspiranes (20). The reaction provides access to damascone derivatives 4-7 which have been found in nature. These synthetic experiments lend support to our hypotheses concerning the biogenesis of damascones from suitable carotenoids or their metabolites.
- Ohloff, Guenther,Rautenstrauch, Valentin,Schulte-Elte, Karl H.
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p. 1503 - 1513
(2007/10/10)
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- 148. The synthesis of damascenone and β-damascone and the possible mechanism of their formation from carotenoids
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A brief synthesis of damascenone (5) from the acetylenic diol 2 and also that of β-damascone (8) from β-ionol, resembling the biogenetic synthesis, are described. A possible mechanism for the formation of damascenone from neoxanthin is proposed.
- Isoe, Sachihiko,Katsumura, Shigeo,Sakan, Takeo
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p. 1514 - 1516
(2007/10/11)
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