New acetylenic michael receptor equivalents,

Leyendecker, F.; Comte, Marie-Thérèse

doi:10.1016/s0040-4039(00)85565-3

Cited by 28 publications

(5 citation statements)

References 24 publications

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“…No evidence of the C(3) substituted regioisomer was found either by chromatography or by 1 H-NMR, even after stopping the reaction before the heterodiene had disappeared. This regioselectivity corresponds to that expected for the cycloaddition between enones acting as heterodienes activated with electron-withdrawing substituents at the conjugated p-system [1a] [2], and monosubstituted or unsubstituted captodative olefins [6b] [6c] [17]. In the case of heterodiene 1a, its dimeric [4 þ 2] adduct was the main byproduct, as previously reported for the thermal attempt of a Diels -Alder reaction with a hindered diene [18].…”

Section: Hetero-diels -Alder Reactions Of Captodative Olefins With Alsupporting

confidence: 81%

ChemInform Abstract: Reactivity and Selectivity of Captodative Olefins as Dienes in Hetero‐Diels—Alder Reactions.

Sanabria¹,

Herrera²,

Aguilar³

et al. 2009

ChemInform

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The reactivity and selectivity of the the captodative olefins 1-acylvinyl benzoates 1a -1f and 3a as heterodienes in hetero-Diels -Alder reactions in the presence of electron-rich dienophiles is described. Heterodienes 1 undergo regioselective cycloaddition with the alkyl vinyl etherdienophiles 6a,b and 9 to give the corresponding dihydro-2H-pyrans 7, 8, and 10 under thermal conditions. The reactivity of these cycloadditions depends, to a large extent, on the electronic demand of the substituent in the aroyloxy group of the heterodiene. Frontier-molecular-orbital (FMO; ab initio) and density-functional-theory (DFT) calculations of the ground and transition states account for the reactivity and regioselectivity observed in these processes.

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Section: Hetero-diels -Alder Reactions Of Captodative Olefins With Alsupporting

confidence: 81%

ChemInform Abstract: Reactivity and Selectivity of Captodative Olefins as Dienes in Hetero‐Diels—Alder Reactions.

Sanabria¹,

Herrera²,

Aguilar³

et al. 2009

ChemInform

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“…[2 + 1] Cycloaddition with 2-Sulfonylacrylates. Since Lewis acid-promoted reactions of α,β-unsaturated sulfoxides have received much attention recently, we initially attempted reaction of a sulfoxide analogue of methylenemalonate, the 2-sulfinylacrylate 2 , with 1 . However, reaction did not proceed in the presence of SnCl 4 and ZnBr 2 , which are the most effective Lewis acids in this type of [2 + 1] cycloaddition reaction .…”

Section: Resultsmentioning

confidence: 99%

[2 + 1] Cycloaddition Reactions of a 1-Seleno-2-silylethene to 2-Sulfonylacrylates: Stereoselective Synthesis of Sulfone-Substituted Cyclopropanes

et al. 1999

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Reaction of 1-(phenylseleno)-2-(trimethylsilyl)ethene 1 and methyl or ethyl 2-p-toluene-or benzenesulfonylacrylates 3 in the presence of SnCl 4 at -78°C gave sulfone-substituted cyclopropanes 4 as single stereoisomers. The structure of one of these crystalline cyclopropane products was elucidated by X-ray crystallographic analysis. The relative stereochemistry of the cyclopropane ring carbon (C 2 ) and selenosilylmethyl group was determined as R,R and S,S, which is consistent with previous mechanical considerations and the NOE determination. 2-Sulfinyl acrylate 2 did not undergo this cycloaddition. The difference in reactivity of the sulfoxide 2 and sulfones 3 toward 1 was explained by comparison of LUMO levels of 2-SnCl 4 and 3-SnCl 4 complexes and activation energies in the synclinal addition of 1 to the complexes.

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“…Enone 6 was prepared as shown in Scheme 3. Preparation of α-(phenylsulfoxy) keto esters 14a/15a , as mixtures of diastereomers, was accomplished by the method of Leyendecker [treatment of 3-methyl-2-cyclohexenone with LiCu(CH 3 ) 2 and reaction of the resulting enolate with methyl or ethyl α-(phenylsulfinyl)acrylate] and reduction with Raney nickel or aluminum amalgam gave keto esters 14b/15b , respectively. Chemoselective methylenylation of the ketone carbonyl in 15b was effected with the Nozaki−Lombardo reagent, and the product 16 was converted to ketone 17 in 92% overall yield by the sequence shown.…”

Section: Resultsmentioning

confidence: 99%

Studies on the Synthesis of Acanthodoral and Nanaimoal: Evaluation of Cationic Cyclization Routes

1996

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Intramolecular Lewis acid-promoted reactions of α,β-unsaturated ketone 6 and aldehydes 7 and 8 were examined as potential routes to acanthodoral (1), a structurally interesting natural product. Ketone 6 afforded ene product 22 exclusively, and both 7 and 8 gave mixtures of bicyclic aldehydes 3 and 26 and tricyclic aldehyde 25. The latter most likely results from 7 by intramolecular cyclization of the alkene onto the Lewis acid-activated carbonyl moiety affording carbocation 31 followed by a 1,2-hydride shift and ring closure. Starting from 8, tricyclic aldehyde 25 apparently forms by cyclization to cation 35 and ring closure to cyclobutane 36, followed by ring opening to 31, the same cation as formed in reactions of 7. Nanaimoal (3) results from loss of H+ from 31, and bicyclic aldehyde 26 may be formed in a similar manner or by a concerted ene reaction. The configuration of 25 establishes that the stereochemistry of the initial cyclization to 31 precludes the possible use of this strategy for the synthesis of acanthodoral. However, acid-promoted cyclization of allylic alcohol 23 efficiently gives diene 29 which undergoes selective hydroboration/oxidation to afford nanaimoal.

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New acetylenic michael receptor equivalents,

Cited by 28 publications

References 24 publications

ChemInform Abstract: Reactivity and Selectivity of Captodative Olefins as Dienes in Hetero‐Diels—Alder Reactions.

ChemInform Abstract: Reactivity and Selectivity of Captodative Olefins as Dienes in Hetero‐Diels—Alder Reactions.

[2 + 1] Cycloaddition Reactions of a 1-Seleno-2-silylethene to 2-Sulfonylacrylates: Stereoselective Synthesis of Sulfone-Substituted Cyclopropanes

Studies on the Synthesis of Acanthodoral and Nanaimoal: Evaluation of Cationic Cyclization Routes

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