Diastereoselective Fischer-Type Pyrroloindole Synthesis and Its Application to the Synthesis of Chiral Pyrroloindole Alkaloids

Nishida, Atsushi; Ushigome, Satoru; Sugimoto, Ayako; Arai, Shigeru

doi:10.3987/com-05-s(k)71

Cited by 18 publications

(6 citation statements)

References 4 publications

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“…85 The third short synthesis of (−)-178a and (±)-esermethole 178b 86 has been completed using Fisher-type pyrroloindole synthesis using a chiral hydrazine as a key step (Scheme 29). 87 Total syntheses of the reverse prenylated marine natural products (±)-flustramine A 183 88 and (±)-flustramine C 184, 89 isolated from Flustra foliacea, have been reported (Scheme 30). 90 185 followed by substitution with prenylstannane in the presence of cesium carbonate as a key step.…”

Section: Physostigmine and Related Compoundsmentioning

confidence: 99%

Simple indole alkaloids and those with a nonrearranged monoterpenoid unit

2007

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Section: Physostigmine and Related Compoundsmentioning

confidence: 99%

Simple indole alkaloids and those with a nonrearranged monoterpenoid unit

2007

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“…[135] The authors later made this chemistry enantioselective by using chiral hydrazines, which they readily prepared from commercially available chiral amines. [207] Synthesis of HPI by simultaneous formation of N b ÀC 8a and N 8 ÀC 8a bonds (J, Scheme 5)…”

Section: Wwwchemeurjorgmentioning

confidence: 99%

Structure, Bioactivity and Synthesis of Natural Products with Hexahydropyrrolo[2,3‐b]indole

Ruiz-Sanchis

Savina

Alberício

et al. 2011

Chemistry A European J

450

199

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Research on natural products containing hexahydropyrrolo[2,3-b]indole (HPI) has dramatically increased during the past few years. Newly discovered natural products with complex structures and important biological activities have recently been isolated and synthesized. This review summarizes the structures, biological activities, and synthetic routes for natural compounds containing HPI, emphasizing the different strategies for assembling this motif. It covers a broad range of molecules, from small alkaloids to complex peptides.

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“…Kikugawa and co-workers reported a four-step method to prepare hydrazines 5 . Nishida and Garg reported a three-step method for the preparation of hydrazines 3 , respectively (Scheme ). Although various 1,1-disubstituted hydrazines could be obtained by these methods, the atom economy of these methods is very low since multiple synthesis processes are required.…”

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confidence: 99%

Reductive Hydrazination with Trichlorosilane: A Method for the Preparation of 1,1-Disubstituted Hydrazines

Wang

et al. 2016

Org. Lett.

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A straightforward and facile method has been developed to prepare 1,1-disubstituted hydrazines via Lewis base promoted direct reductive hydrazination. Under the catalysis of hexamethylphosphoramide (HMPA) and N,Ndimethylacetamide (DMAc), respectively, various ketones and aldehydes could react with phenylhdrazines to prepare 1,1-disubstituted hydrazines with good to high yields. D irect reductive amination (DRA) represents a convenient and straightforward method for the synthesis of amines, which have seen wide applications in organic synthesis. 1−3 The amines that could be used as effective reactants for DRA include various primary and secondary alkyl amines, 4−6 aryl amines, 7−11 hydroxyl amines, 12 and alkoxyl amines. 13 As a special type of amines, hydrazines should in principle also be good reactants for DRA. To date, however, there have been no organocatalytic methods reported in the literature that could implement DRA using hydrazines as reactants, so-called direct reductive hydrazination (DRH). 14 Since hydrazines have two vicinal amino groups, conceivably, the difficulties confronted with DRH include the following: (1) the in situ formed hydrazone intermediate (A, Scheme 1) is normally much more stable and less reactive than the carbonyl substrates toward nucleophilic reduction; (2) the regioselectivity is hard to control if the two amino groups are both active and have different substitutions. The use of preformed hydrazones and thus indirect reductive hydrazination (IRH) method could address these difficulties to some degree, but it needs extra operations and is less convenient and economic. 15−18 Hydrosilylation of unsaturated double bonds by trichlorosilane with Lewis base as an activator is a well-known reduction method. 19−22 Its strength has been well demonstrated by others and us in asymmetric catalysis. 23−34 We were interested in extending the application of this method to DRH. The chance is that trichlorosilane should preferentially react with the terminal amino group of hydrazine 2 and leave the middle amino group to interact with the carbonyl group of 1. The resulting intermediate B should be highly active toward the hydrosilylation. Herein, we wish to communicate the results of our study and present a highly effective new method to implement DRH using organic Lewis base as promoter and trichlorosilane as reducing agent, which furnishes the condensation of various aldehydes and ketones with aryl hydrazines and reduction in one-pot under mild conditions to afford 1,1-disubstituted hydrazines as exclusive regioisomers with good to high yields.1,1-Disubstituted hydrazines 3 are important organic synthons used in a various of reactions such as Fisher indolization for the synthesis of indole and its derivatives. Kikugawa and co-workers 35 reported a four-step method to

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Diastereoselective Fischer-Type Pyrroloindole Synthesis and Its Application to the Synthesis of Chiral Pyrroloindole Alkaloids

Cited by 18 publications

References 4 publications

Simple indole alkaloids and those with a nonrearranged monoterpenoid unit

Simple indole alkaloids and those with a nonrearranged monoterpenoid unit

Structure, Bioactivity and Synthesis of Natural Products with Hexahydropyrrolo[2,3‐b]indole

Reductive Hydrazination with Trichlorosilane: A Method for the Preparation of 1,1-Disubstituted Hydrazines

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