2017
DOI: 10.1002/adsc.201700932
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Synthesis of Spiroindolenines via Regioselective Gold(I)‐Catalyzed Cyclizations of N‐Propargyl Tryptamines

Abstract: N-Propargyl tryptamines bearing N-substituents such as propargyl, allyl, alkyl or benzyl groups undergo regioselective gold-catalyzed cyclizations to the corresponding spiroindolenines, while it was previously shown that N-sulfonyl-N-propargyl tryptamines lead to achiral azepino [4,5-b]indoles. An asymmetric approach to these spiroindolenines is disclosed using chiral gold complexes, leading to enantiomeric ratios up to 84/16. The spiroindolenines could be late-stage functionalized using Huisgen cyclizations, … Show more

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Cited by 65 publications
(31 citation statements)
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“…After the pioneering findings of Echavarren, [33,47] several research groups studied the synthesis of six-, seven-, or eight-membered-ring derivatives through carbocyclization of different alkynylindoles. [47] A similar mechanism -involving gold activation of an alkyne, nucleophilic addition of C-3 of indole to form a spirocyclic compound, and vinyl 1,2-migration, prior to rearomatization and protodeauration -was also invoked by Enders [48] and Van Der Eycken, [49,50] among others, [51][52][53] to justify the cyclization of alkynylindoles to afford different polycycles. Thus, gold(III) afforded 34 through an unprecedented 8-endo-dig process, whereas cationic gold(I) catalyst led to 35 through a 7-exo-dig cyclization.…”
Section: Intramolecular Hydroarylation Of Alkynesmentioning
confidence: 94%
See 1 more Smart Citation
“…After the pioneering findings of Echavarren, [33,47] several research groups studied the synthesis of six-, seven-, or eight-membered-ring derivatives through carbocyclization of different alkynylindoles. [47] A similar mechanism -involving gold activation of an alkyne, nucleophilic addition of C-3 of indole to form a spirocyclic compound, and vinyl 1,2-migration, prior to rearomatization and protodeauration -was also invoked by Enders [48] and Van Der Eycken, [49,50] among others, [51][52][53] to justify the cyclization of alkynylindoles to afford different polycycles. Thus, gold(III) afforded 34 through an unprecedented 8-endo-dig process, whereas cationic gold(I) catalyst led to 35 through a 7-exo-dig cyclization.…”
Section: Intramolecular Hydroarylation Of Alkynesmentioning
confidence: 94%
“…In both cases the first reaction step is an intramolecular cyclization, leading to spirocyclic intermediates XVII and XVIII, which further evolve to the final products after 1,2-migration of the vinyl group (Scheme 14). [47] A similar mechanism -involving gold activation of an alkyne, nucleophilic addition of C-3 of indole to form a spirocyclic compound, and vinyl 1,2-migration, prior to rearomatization and protodeauration -was also invoked by Enders [48] and Van Der Eycken, [49,50] among others, [51][52][53] to justify the cyclization of alkynylindoles to afford different polycycles. On the other hand, different research groups have concentrated their attention on the study of alternative mechanistic pathways, including other types of 1,2-migrations of spirocyclic intermediates, starting from indoles bearing alkynes on the C-3 position.…”
Section: Intramolecular Hydroarylation Of Alkynesmentioning
confidence: 99%
“…[ 13 ] However, gold has been rarely used in CADA reactions compared to other transition metals. [ 14–17 ] An example of gold‐catalyzed dearomatization involving one alkyne unit was shown by Bandini et al [ 18 ] They converted naphthyl propargyl ethers 1 to naphthalene‐2‐one derivatives 2 (Scheme 1a). This reaction can be considered as a Claisen rearrangement with subsequent intramolecular hydroxy group addition to the newly formed allene.…”
Section: Methodsmentioning
confidence: 99%
“…Gold complexes are highly effective catalysts to trigger the addition of nucleophiles to alkynes [1][2][3][4][5][6]. Over the last few years, the functionalization of indoles using gold catalysis has stimulated very active research in the fields of catalysis and organic synthesis.…”
Section: Introductionmentioning
confidence: 99%
“…Over the last few years, the functionalization of indoles using gold catalysis has stimulated very active research in the fields of catalysis and organic synthesis. It is now well established that indoles can react with alkynes in an intramolecular fashion, upon exposure to Au(I) or Au(III) catalysts, via either their positions 2 or 3 [1,3,6]. When the alkyne is tethered to the 3-position of the indole and if position 2 is substituted, the compound will undergo dearomatizing cyclization [7][8][9], as illustrated by the conversion of the 2-methyltryptamine derivative 1 (X = Me) into the spiro-compound 2 [10] (Scheme 1).…”
Section: Introductionmentioning
confidence: 99%