41793-01-5Relevant articles and documents
Pd-Catalyzed Redox Divergent Coupling of Ketones with Terpenols
Zhao, Chao-Yang,Ji, Ding-Wei,Zheng, Hao,He, Gu-Cheng,Liu, Heng,Hu, Yan-Cheng,Chen, Qing-An
, p. 6825 - 6834 (2021/06/28)
Redox diversity is a common and important feature of nature. Herein, a Pd-catalyzed redox divergent coupling of ketones with terpenols has been developed to access α-substituted ketones with varying degrees of unsaturation. The control of oxidation states of the product is facilitated by employing different additives. With the aid of BnOH as an external hydrogen source, a reductive coupling pathway is thermodynamically favored. The use of LiBr as the additive will reduce the reactivity of Pd-H to divert the selectivity toward α,β-unsatuated ketones. By switching the solvent from toluene to chlorobenzene, the active species Pd-H will be fully quenched to enable oxidative coupling. Gram-scale reaction with lower catalyst loading (0.5 mol %) was also accomplished to highlight the practicability of this protocol. Furthermore, detailed experimental studies were carried out to elucidate the reaction mechanism and the factors enabling manipulation of the redox selectivity. This redox divergent coupling protocol provides an important complement for known precedents on Tsuji-Trost allylation of ketones.
Methods for preparing aldehydes by self-aldol condensation
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Page/Page column 6, (2009/10/31)
Methods for preparing self-aldol condensation products of prenyl aldehyde (3-methyl-2-butenal) by use of an amine catalyst under weakly acidic conditions at temperatures of 10° C. or higher are disclosed. Methods are disclosed for the selective formation of α-1,2-adducts and γ-1,2-adducts of prenyl aldehyde, and for the formation of specialty compositions useful in the flavor and fragrance industries.
Synthesis and cellular effects of cycloterpenals: Cyclohexadienal-based activators of neurite outgrowth
Bench, Bennie J.,Tichy, Shane E.,Perez, Lisa M.,Benson, Jenna,Watanabe, Coran M.H.
scheme or table, p. 7573 - 7581 (2009/04/04)
An unusual class of diterpenoid natural products, 'cycloterpenals' (with a central cyclohexadienal core), that arise in nature by condensation of retinoids and other isoprenes, have been isolated from a variety of organisms including marine sponges as well as from the human eye. A milk whey protein has also demonstrated the formation of a cycloterpenal derived from β-ionylidineacetaldehyde. Here, we generate a synthetic library of these molecules where we detail reaction conditions required to effect cross condensation of α,β-unsaturated aldehydes as opposed to homodimerization. The ability of this class of molecules to activate neurite outgrowth activity is reported.
Enantioselective organocatalytic formal [3 + 3]-cycloaddition of α,β-unsaturated aldehydes and application to the asymmetric synthesis of (-)-isopulegol hydrate and (-)-cubebaol
Hong, Bor-Cherng,Wu, Ming-Fun,Tseng, Hsing-Chang,Liao, Ju-Hsiou
, p. 2217 - 2220 (2007/10/03)
The first highly enantioselective organocatalyzed carbo [3 + 3] cascade cycloaddition of α,β-unsaturated aldehydes is reported. Using this methodology, crotonaldehyde is converted to 6-hydroxy-4-methylcyclohex-1- enecarbaldehyde, which is used in the synthesis of (-)-isopulegol hydrate, (-)-cubebaol, and p-tolualdehyde as well as (-)-6-hydroxy-4-methyl-1- cyclohexene-1-methanol acetate, an intermediate in the total synthesis of lycopodium alkaloid magellanine. Other α,β-unsaturated aldehydes give rise to chiral cyclohexadienes via formal [4 + 2] reactions.
Initial interaction of triphenylphosphonium-2-propenylide with prenal prior to Wittig olefination
Schneider, David F.,Venter, Abraham C.
, p. 3067 - 3081 (2007/10/03)
The interaction of triphenylphosphonium-2-propenylide (2) with prenal (6) is shown to proceed via initial C(γ)-C1 addition, followed by dissociation of the coupling product and C(α)-C1 recombination to produce the corresponding betaine, which eliminates triphenyphosphine oxide to yield (E)- and (Z)-6-methyl-1,3,5-triene (7a,b) as the Wittig olefination products.
Regioselective addition of the prenal potassium dienolate onto α,β- unsaturated aldehydes. A short access to polyenaldehydes
Cahard, Dominique,Poirier, Jean-Marie,Duhamel, Pierre
, p. 7093 - 7096 (2007/10/03)
The potassium dienolate of prenal obtained by treatment of the corresponding dienoxysilane with tBuOK was reacted with enaldehydes. In all cases a γ-specific reaction occurs. According to the reaction conditions a γ ;1,2 or a γ ;1,4 coupled product was selectively obtained with enals. The γ;1,2 reaction provided an efficient prenylation procedure. A short two- step synthesis of retinal is described.
Condensation of all-E-retinal
Verdegem, Peter J. E.,Monnee, Menno C. F.,Mulder, Patrick P. J.,Lugtenburg, Johan
, p. 5355 - 5358 (2007/10/03)
A novel base induced self condensation product of all-E-retinal is presented. The scope of the reaction is investigated with three analogous α,β-unsaturated aldehydes.
Synthesis of inverto-yuehchukene and its 10-(indol-3′-yl) isomer. X-Ray structure of (4aRS,10aRS)-1,1,3-trimethyl-1,2,4a,5,10,10a-hexahydroindene[1,2-b]indol-10-one
Cheng, Kin-Fai,Cheung, Man-Ki
, p. 1213 - 1218 (2007/10/03)
A total synthesis of inverto-yuehchukene 4 and its 10-(indo-3′-yl) isomer 7 is described. The key tetracyclic ketone intermediate 13 was synthesized by a coupling reaction between 3-indolylzinc reagent and acid chloride 11, followed by Nazarov cyclization
The proline and β-lactoglobulin mediated asymmetric self-condensation of β-ionylideneacetaldehyde, retinal and related compounds
Asato,Watanabe,Li,Liu
, p. 3105 - 3108 (2007/10/02)
Proline was found to effectively mediate the asymmetric reaction of β-ionylideneacetaldehyde 1A, retinal and related α,β-unsaturated aldehydes to form their corresponding self-condensation products in reasonable enantiomeric excess (up to 65% ee). This sa
CONDENSATION OF ETHYL AND METHYL 4-(TRIPHENYLPHOSPHORANYLIDENE)-3-OXOBUTANOATE WITH ENALS
Moorhoff, Cornelis M.,Schneider, David F.
, p. 4721 - 4724 (2007/10/02)
The manipulation of the mode of reaction of 4-(phosphoranylidene)-3-oxobutanoates with enals and a resulting new synthesis of ethyl β-safranate have been explored.
