Total regiospecific synthesis of the selagine tricyclic ring system

Gravel, Denis; Bordeleau, Luc; Ladouceur, Gaétan; Rancourt, James D.; Thoraval, D.

doi:10.1139/v84-499

Cited by 7 publications

(4 citation statements)

References 4 publications

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“…Not surprisingly,c atalytic palladium was found to accelerate this process,b ut it also had an unexpectedly large impact on the diastereoselectivity;i nt he presence of Pd(PPh 3 ) 4 , 30 cyclized to 31 in a1 9:1r atio favoring the cisisomer. [20] Genet used as imilar stereospecific allylic alkylation reaction to install the cyclopropane moiety in his semi-synthesis of the marine sterol gluacasterol (43). [19] An intermolecular-intramoleculara llylic alkylation sequence with as tabilized carbonn ucleophile also figuredp rominently in Genet's synthesis of the dictyopterenes (Scheme 10).…”

Section: Carbon-carbon Nucleophilesmentioning

confidence: 99%

“…[41] Several years later,G ravel and co-workers showedt hat the same transformationc ould be achieved with cyclic b-ketoesters 128 (Scheme 29 a). In their efforts towards selagine, [43] whichwas later shown to be identical to (À)-huperzine A( 130), [44] Gravele tal. [41] The synthesis of 129 d in 76 %y ield is particularly notable, as it highlights the beneficial effect of palladium catalysis in promoting ac lean cyclization.…”

Section: Carbon-carbon Nucleophilesmentioning

confidence: 99%

“…The resulting trans-cyclopropane (38 a) was stable, but the analogous cis-c ompound spontaneously underwent aC ope rearrangement to give the ring-expanded product 38 b. [20] Genet used as imilar stereospecific allylic alkylation reaction to install the cyclopropane moiety in his semi-synthesis of the marine sterol gluacasterol (43). The route commenced with the addition of an alkynyl lithium to 39,which was synthesized from readily available stigmasterol in three steps using classical steroid chemistry (Scheme1 1).…”

Section: Carbon-carbon Nucleophilesmentioning

confidence: 99%

“…[41] The synthesis of 129 d in 76 %y ield is particularly notable, as it highlights the beneficial effect of palladium catalysis in promoting ac lean cyclization. In their efforts towards selagine, [43] whichwas later shown to be identical to (À)-huperzine A( 130), [44] Gravele tal. prepared the same compound 129 d under transition metal-free conditions from 128 d and dichloride 126 b and obtained am uch lower yield (Scheme 29 b).…”

Section: Carbon-carbon Nucleophilesmentioning

confidence: 99%

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Annulative Allylic Alkylation Reactions between Dual Electrophiles and Dual Nucleophiles: Applications in Complex Molecule Synthesis

Trost

Kalnmals

2019

Chemistry A European J

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Metal-catalyzed allylic alkylation reactions between dual nucleophiles and dual electrophiles represent ap owerful set of methodsf or the synthesis of small-, medium-, and even large-sized rings. Using this strategy,ahandful of simple allylic diol derivatives can be transformed into a broad array of complexc arbo-and heterocycles of varying ring sizes in just as ingle step. Because of their ability to rapidly generate complexity, annulative allylic alkylationr eactions between dual nucleophiles and dual electrophiles have been extensively employed in the total synthesis of both naturalp roducts and pharmaceuticalcompounds.Scheme1.GeneralScheme for metal-catalyzed allylic alkylation.Scheme2.GeneralScheme for annulative allylic alkylation reactionsu sing a dual electrophile.Scheme3.Differenttypesofa nnulativeallylic alkylation reactions.Scheme4.GeneralScheme for allylic alkylation reactionsi nvolving 1,1-substitutions.

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Section: Carbon-carbon Nucleophilesmentioning

confidence: 99%

Section: Carbon-carbon Nucleophilesmentioning

confidence: 99%

Section: Carbon-carbon Nucleophilesmentioning

confidence: 99%

Section: Carbon-carbon Nucleophilesmentioning

confidence: 99%

See 2 more Smart Citations

Annulative Allylic Alkylation Reactions between Dual Electrophiles and Dual Nucleophiles: Applications in Complex Molecule Synthesis

Trost

Kalnmals

2019

Chemistry A European J

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Preparation of α,β‐Unsaturated Carbonyl Compounds and Nitriles by Selenoxide Elimination

Reich

Wollowitz²

1993

Organic Reactions

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Hydrogenation and dehydrogenation reactions play a key role in synthetic organic chemistry. The discoveries that selenium and sulfur substituents could be easily introduced α to a variety of acidifying functional groups, and that these derivatives could be smoothly converted to olefins by selenoxide or sulfoxide syn elimination under mild conditions greatly broadened the range of α,β‐unsaturated carbonyl compounds that could be prepared from their saturated analogs. This chapter covers the preparation from enols or enolates of α‐RSe substituted carbonyl compounds and nitriles and their conversion to olefins by thermolysis of the derived selenoxides. Other procedures for preparing these compounds are discussed in a limited way, and they are included in the tables, but the two‐step dehydrogenation is by far the most frequently used. The rapid acceptance of the selenoxide elimination as a synthetic procedure was the result of two factors: the ease with which many organoselenium compounds could be prepared using readily available, powerful electrophilic and nucleophilic selenium reagents, and the mild conditions (−50° to 40°) under which selenoxides fragment to olefins. Recognized selenoxide eliminations to form olefins were reported in 1967 and 1970, well after the related sulfoxide eliminations had been studied extensively. The application of the sulfoxide and selenoxide eliminations were reported almost simultaneously by several groups in 1973. These reactions have been the subject of several reviews. The principal procedures and reagents for the preparation of the requisite selenium compounds were also identified at that point. Preparations discussed in this chapter are Method A: Reaction of enolates, enols, enol ethers, and enamines with benzeneselenenyl chloride or bromide, or diphenyl diselenide. Method B: Reaction of enols with seleninylating agents [C 6 H 5 Se(O)Cl, (C 6 H 5 SeO) 2 O]. Method C: Nucleophilic substitution of α‐halo carbonyl compounds with metal selenolates. Method D: Alkylation of α‐phenylseleno carbonyl compounds and acylation of α‐lithio selenides or selenoxides.

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Synthetic studies of huperzine A and its fluorinated analogues. 1. Novel asymmetric syntheses of an enantiomeric pair of huperzine A

et al. 1998

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Total regiospecific synthesis of the selagine tricyclic ring system

Cited by 7 publications

References 4 publications

Annulative Allylic Alkylation Reactions between Dual Electrophiles and Dual Nucleophiles: Applications in Complex Molecule Synthesis

Annulative Allylic Alkylation Reactions between Dual Electrophiles and Dual Nucleophiles: Applications in Complex Molecule Synthesis

Preparation of α,β‐Unsaturated Carbonyl Compounds and Nitriles by Selenoxide Elimination

Synthetic studies of huperzine A and its fluorinated analogues. 1. Novel asymmetric syntheses of an enantiomeric pair of huperzine A

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