Showing papers on "Enone published in 1990"
TL;DR: In this article, a general strategy for the synthesis of highly substituted polycyclic aromatic and heteroaromatic compounds was developed, which is achieved simply by the irradiation of a dichloroethane solution of an acetylene derivative and a vinyl or aryl α-diazo ketone.
Abstract: A general strategy for the synthesis of highly substituted polycyclic aromatic and heteroaromatic compounds has been developed. The new aromatic annulation is achieved simply by the irradiation of a dichloroethane solution of an acetylene derivative and a vinyl or aryl α-diazo ketone. Mechanistically, the reaction proceeds via the photochemical Wolff rearrangement of the diazo ketone to generate an aryl- or vinylketene, followed by a cascade of three pericyclic reactions. A variety of substituted phenols, naphthalenes, benzofurans, benzothiophenes, indoles, and carbazoles can be prepared by using the method
166 citations
TL;DR: In this article, the presence of biphenylenediol 8 accelerates the rate of some Diels-Alder reactions, and a complex involving two hydrogen bonds is proposed.
127 citations
121 citations
TL;DR: In this paper, the cycloadditive strategy complements existing asymmetric aldol routes to such functional groups, such as β,γ-dihydroxy ketones, alcohols, and 1,2-and 1,3-diols.
Abstract: Syntheses of the three title natural products are used to illustrate that optically pure isoxazolines can be transformed into a wide variety of functional groups including β,γ-dihydroxy ketones, alcohols, 1,2- and 1,3-diols, 1,3,4-triols, 1,3-amino alcohols, and 1,3,4-amino diols. It is suggested that this cycloadditive strategy complements existing asymmetric aldol routes to such functionality
112 citations
109 citations
TL;DR: In this article, catalytic quantities of Rh(PPh 3 ) 3 Cl greatly accelerate the 1,4-addition process, effecting conjugate reduction of these substrates by catecholborane at -20°C.
Abstract: α,β-Unsaturated ketones which can readily adopt an s-cis conformation undergo conjugate reduction by catecholborane at room temperature. α,β-Unsaturated imides, esters, and amides are unreactive under the same conditions. However, catalytic quantities of Rh(PPh 3 ) 3 Cl greatly accelerate the 1,4-addition process, effecting conjugate reduction of these substrates by catecholborane at -20°C. The resulting boron enolates may be reacted with electrophiles to provide functionalized products
101 citations
90 citations
81 citations
TL;DR: The cyclization of 2'-aminochalcone (2a) and its side-chain additives has been studied for the development of syntheses of 2-aryl-4-quinolones.
Abstract: The cyclization of 2'-aminochalcone (2a) and its side-chain additives has been studied for the development of syntheses of 2-aryl-4-quinolones. 2a and its 2'-acetamido 2b and 2'-benzenesulfonamido 2c derivatives underwent acid- or base-catalyzed cyclization to 1,2,3,4-tetrahydro-4-quinolones
80 citations
71 citations
TL;DR: In this article, the use of the stable copper(I) hydride cluster, [(Ph3P)CuH]6, allows chemoselective conjugate reduction of α,β-unsaturated carbonyl compounds substituted at the γ-position with leaving groups.
TL;DR: The carbocyclic nucleosides (−)-aristeromycin and (−)-neplanocin A were made enantiospecifically in nine steps and ten steps, respectively, from D-ribonic acid γ-lactone.
Abstract: The carbocyclic nucleosides (−)-aristeromycin and (−)-neplanocin A were made enantiospecifically in nine steps and ten steps, respectively, from D-ribonic acid γ-lactone. Quenching of an organocuprate conjugate addition reaction with either acetic acid or methanesulfinyl chloride determines whether the divergent synthetic route branches toward (−)-aristeromycin or (−)-neplanocin A
TL;DR: The reaction de cyclobutenones avec le complexe Cl Rh (PPh 3 ) 3 donne les complexes (η 2 -vinylcetene) rhodacyclopent-3-en-2-ones as discussed by the authors.
TL;DR: In this paper, the electroreductive cyclization reaction has been successfully applied to an efficient formal total synthesis of quadrone and two of the four rings were created electrochemically, a third via a novel oxidativedecarboxylation and cyclization onto a remote nitrile functional group.
TL;DR: The cyclic methylene compounds (1, 2, 3) undergo diastereoselective free radical addition when treated with alkylmercury hydride or alkyln iodide/tributylstannane to give products useful for the enantioselectively synthesis of α-amino and α-hydroxy acids as discussed by the authors.
Abstract: The cyclic methylene compounds (1)–(3) undergo diastereoselective free radical addition when treated with alkylmercury hydride or alkyl iodide/tributylstannane to give products useful for the enantioselective synthesis of α-amino and α-hydroxy acids.
TL;DR: The corresponding epoxides were isolated in excellent yields via oxygen transfer by dimethyldioxirane ( as acetone solution) as discussed by the authors, and they were used to synthesize the corresponding epoxide.
TL;DR: In this paper, the glyoxalase 1 inhibitor COTC (2-crotonyloxymethyl-(4 R,5 R,6 R )-4,5,6-trihydroxycyclohex-2-enone) was synthesized from (-)-quinic acid in thirteen steps; an interesting rearrangement involving a silyl migration upon oxidation of ( l10 ) is also described.
TL;DR: Hetero-Diels-alder reaction of β,β-bis(trifluoroacetyl)vinyl ethers, which are prepared by acylation of vinyl ethers with trifluoracetic anhydride, with electron-rich alkenes such as vinyl ether, ethyl vinyl sulfide and 1,1-diphenoxyethylene proceed quite easily under mild conditions to afford 2,4-dialkoxy-, 2,ethoxy-4-phenoxy-, 3,4dihydro-2H
Abstract: Hetero-Diels-alder reaction of β,β-bis(trifluoroacetyl)vinyl ethers, which are prepared by acylation of vinyl ethers with trifluoroacetic anhydride, with electron-rich alkenes such as vinyl ethers, ethyl vinyl sulfide and 1,1-diphenoxyethylene proceed quite easily under mild conditions to afford 2,4-dialkoxy-, 2-ethoxy-4-phenoxy-, 2-ethylthio-4-alkoxy-, 2-2diphenoxy-4-ethoxy- and 2,4-diaryloxy-5-trifluoroacetyl-6-trifluoromethyl-3,4-dihydro-2H-pyrans in excellent yields
TL;DR: In this article, a wide variety of easily accessible Hagemann's esters are converted to p-methoxybenzoates with iodine and methanol, and the conversion is shown to be successful.
TL;DR: In the presence of bromure de lithium/1,8-diazabicyclo [5.4.0] undec-7-ene, de [(2,2-dimethylpropylidene)-amino] acetate de methyle and de 2-[(2, 2 -dimethylproylidenes) amino] propanoate, obtention d'une addition anti-and syn-selective de Michael avec, respectivement, des isomeres E et Z d'esters α,β-insatures
Abstract: En presence de bromure de lithium/1,8-diazabicyclo [5.4.0] undec-7-ene, de [(2,2-dimethylpropylidene)-amino] acetate de methyle et de 2-[(2,2-dimethylproylidene) amino] propanoate, obtention d'une addition anti- et syn-selective de Michael avec, respectivement, des isomeres E et Z d'esters α,β-insatures et des cetones. La cyclisation hydrolytique des composes d'addition de Michael conduit a des 5-oxopyrrolidine-2-carboxylates et a des 1-pyrroline-5-carboxylates
TL;DR: Trialkylsilyl triflate promotes conjugate addition of alkynylzinc compounds to α,β-enones to afford γ,δ-acetylenic silyl enol ethers.
TL;DR: Addition d'homoenolates de zinc a des esters acetyleniques conduisant a une addition conjuguee suivie d'une acylation intramoleculaire de l'allenolate intermediaire pour donner des 2-carbalkoxycyclopentenones, il s'agit d'un cycloaddition formelle [3+2] en une seule operation as discussed by the authors.
Abstract: Addition d'homoenolates de zinc a des esters acetyleniques conduisant a une addition conjuguee suivie d'une acylation intramoleculaire de l'allenolate intermediaire pour donner des 2-carbalkoxycyclopentenones, il s'agit d'une cycloaddition formelle [3+2] en une seule operation
TL;DR: In this article, 1-Alkenyldialkoxyboranes react with α,β-unsaturated ketones in the presence of BF 3 etherate through a facile 1,4-addition manner to give γ,δ-uniform ketones stereoselectively.
TL;DR: The syn-selective aldol reaction of β-chlorovinyl ketones using dienol borinates can be coupled with a trimethylsilyltriflate promoted cyclisation to give cis-dihydropyrones.
TL;DR: In this article, the synthesis of enantiomerically pure grasshopper ketons (i.e., 4-(2,4,dihydroxy-2,6, 6, 6), but-3-en-2-ons) and their oxo derivatives was performed.
Abstract: Synthesis of Optically Pure Grasshopper Ketone and of Its Diastereoisomers and Related Compounds
Starting from our previously described synthon 1, the synthesis of four enantiomerically pure grasshopper ketons (diastereoisomeric 4-(2′,4′-dihydroxy-2′,6′,6′-trimethylcyclohexylidene)but-3-en-2-ons) and of their oxo derivatives was performed. Spectral and chiroptical data are presented.
TL;DR: In this article, the reaction of 1 with cyclic and acyclic α,β-unsaturated carbonyl compounds and α-nitro olefins in the presence of TiCl 4 to give the corresponding conjugate propargylation products was described.
Abstract: Stannylallenes (1) reacted with α,β-unsaturated carbonyl compounds and α-nitro olefins in the presence of TiCl 4 to give the corresponding conjugate propargylation products. Thus, the reaction of 1 with cyclic and acyclic α,β-unsaturated carbonyl compounds (2) gave β-propargylic ketones (3) in high yields. With α-nitro olefins (4), two types of products, β-propargylic nitroalkanes (5) and α-propargylic ketones (6), were obtained selectively depending on the presence or absence of the α-substituent of 4. Transformations of the products (6) to cyclopentenone derivatives are also described
TL;DR: In this article, a facile synthesis of isopropyl 2,2-difluorovinyl ketone and 3,3-Difluoroacrylate and some unusual addition reactions of these olefins with nitronate anions and β-nitro al
Abstract: This report describes a facile synthesis of isopropyl 2,2-difluorovinyl ketone and isopropyl 3,3-difluoroacrylate and some unusual addition reactions of these olefins with nitronate anions and β-nitro al