Aerobic Palladium(II)‐Catalyzed 5‐<i>endo</i>‐<i>trig</i> Cyclization: An Entry into the Diastereoselective C‐2 Alkenylation of Indoles with Tri‐ and Tetrasubstituted Double Bonds

Kandukuri, Sandeep R.; Schiffner, Julia A.; Oestreich, Martin

doi:10.1002/anie.201106927

Cited by 80 publications

(53 citation statements)

References 60 publications

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“…These reactants smoothly afforded the structurally significant 3H-pyrrolo[1,2-a]indol-3-one compounds via palladium(II)-catalyzed aerobic 5-endo-trig cyclization (Scheme 4). [12] While Pd(OAc) 2 was used in a catalytic amount, nicotinonitrile and pivalic acid were added as efficient additives for the present aerobic annulation. With a simple late-stage treatment, this synthetic route offered a stepwise entry into the diastereoselective C2 alkenylation of indoles.…”

Section: Indole Alkenylationmentioning

confidence: 99%

Aerobic Oxidative Functionalization of Indoles

et al. 2020

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The synthetic methodology for direct indole functionalizations is of great significance in indole chemistry and has been intensively investigated in the last few decades. From the perspective of green chemistry, oxygen is the best choice as the terminal oxidant in molecular synthesis. Hence, aerobic oxidative functionalization of indoles became a hot research topic in the last decade. Numerous efficient protocols in this field have been discovered that enable facile and efficient transformations of indoles to related valuable compounds, which are summarized and discussed in detail in this review.

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Section: Indole Alkenylationmentioning

confidence: 99%

Aerobic Oxidative Functionalization of Indoles

et al. 2020

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“…The inherent difficulty in using trisubstituted alkenes in the FM reaction has spurred the search for an alternative procedure that could avoid the isomerization process. N ‐Acryloyl indoles undergo to an intramolecular FM reaction in the presence of Pd(OAc) 2 using 3‐pyridyl cyanide as ligand (Scheme ) . The intermediate pyrroloindolones thus obtained are converted into the open chain 2‐alkenylated indoles by a simple basic hydrolysis and methyl esterification with trimethylsilyl diazomethane.…”

Section: Transition Metal C−h Activation Of Indoles and Alkenesmentioning

confidence: 99%

“…N-Acryloyl indoles undergo to an intramolecular FM reaction in the presence of Pd(OAc) 2 using 3-pyridyl cyanide as ligand (Scheme 12). [42] The intermediate pyrroloindolones thus obtained are converted into the open chain 2-alkenylated indoles by as imple basic hydrolysis and methyl esterification with trimethylsilyl diazomethane. Although the overall yields of the final products are moderate, this methodi sp articularly useful for the preparation of trisubstituted alkenylated indoles allowing at otal control of the double bond stereochemistry.I nc onnectionw ith C-2 alkenylations, other transition metals have shown their activity as catalysts for these reactions.…”

Section: C-2 Alkenylationsmentioning

confidence: 99%

Regioselective Direct C‐Alkenylation of Indoles

Petrini

2017

Chemistry A European J

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The direct introduction of alkenyl groups into the indole framework avoiding its preliminary functionalization can be carried out using different synthetic strategies. Transition-metal complexes facilitate the C-H activation of indoles or alkenes allowing an efficient Csp - Csp bond formation. The hydroindolation of alkynes catalyzed by the same metal complexes or various acidic promoters can also be pursued for the alkenylation process. Conjugate addition of electron-poor alkenes and direct condensation of carbonyl derivatives with indoles are also of interest for this purpose. The regiochemical control can be exploited using the intrinsic C-3 reactivity of the indole ring. The introduction of a suitable directing group at the nitrogen atom allows the preparation of C-2 alkenylated derivatives by transition metal catalyzed reactions. This review collects the fundamental contributions in this field reported in literature during the last fifteen years.

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“…The Pd(II)-catalyzed 5- endo -trig cyclization of N -alkenoylindoles 25 in the presence of 3-cyanopyridine as the ligand and under aerobic conditions afforded the tricyclic products 26 (Scheme 15) [70]. The subsequent amide cleavage carried out in aqueous NaOH and following ester formation by treatment with Me 3 SiCHN 2 in methanol led to the 2-alkenylated indoles 27 .…”

Section: Reviewmentioning

confidence: 99%