Synthesis of Spirocarbamate Oxindoles via Intramolecular Trapping of a β-Silyl Carbocation by an <i>N</i>-Boc Group

Shupe, Benjamin H.; Allen, Emily E.; MacDonald, Jacob P.; Wilson, Sean O.; Franz, Annaliese K.

doi:10.1021/ol4010867

Cited by 37 publications

(17 citation statements)

References 63 publications

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“…The outcome of the allylation of isatin ketimines using allylsilanes is strongly affected by the nature of the catalyst employed to promote the addition reaction. The utilization of copper salts in the reaction of isatin ketimines with different trialkylallylsilanes 212 directly affords spirocarbamates 214 in satisfactory yield and generally moderate stereoselectivity (Scheme ) . Additives such as sodium tetrakis[(3,5‐trifluoromethyl)phenyl]borate 213 are instrumental in order to obtain better yields of the spiro derivatives, although it has been observed that this salt alone is not able to catalyze the reaction.…”

Section: Spiroheterocyclic Derivativesmentioning

confidence: 99%

Recent Developments in the Stereoselective Synthesis of Nitrogen‐Containing Heterocycles using N‐Acylimines as Reactive Substrates

Marcantoni

Petrini

2016

Adv Synth Catal

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Scheme 3. Enantioselective synthesis of trans-aziridines 8 catalyzed by chiral phosphoric acid 10. Scheme 4. Enantioselective synthesis of trans-aziridines 14. Scheme5.Preparation of chiral aziridines 17. Scheme6.Synthesis of chiral aziridines 20. Scheme 22. Synthesis of chiral 2-pyrrolines 82. Scheme23. Enantioselective synthesis of epi-cytoxazone 89. Scheme 24. Synthesis of the mGluR5modulator 96. Scheme 25. Synthesis of chiral 1,3-oxazolines. Scheme26. Synthesis of chiral imidazolidin-2-one 102. Scheme 27. Enantioselectiven itro-Mannichr eaction.Scheme28. Synthesis of (À)-nutlin-3 111.Scheme29. Synthesis of functionalized tetrahydropyridines. Scheme 32. Synthesis of chiral piperidines 129. Scheme 33. One-pot synthesis of N-formylpiperidines. Scheme34. Synthesis of bicyclic aminal 136. Scheme 39. General synthesis of isatin ketimines. Scheme 40. Asymmetric Staudinger reaction. Scheme41. Synthesis of spirocyclic oxindolo-g-lactams. Scheme 42. Synthesis of methylidenes pirocyclic compounds. Scheme 43. Synthesis of spirooxindolepyrrolines. Scheme44. Synthesis of imidazoline-based spirooxindoles. Scheme 48. Synthesis of spirolactam derivatives. Scheme49. Synthesis of spirooxindolelactams 201. Scheme50. Synthesis of polycyclic spirolactams 203. Scheme 56. Synthesis of chiral spiroazetidin-2-ones 228.

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Section: Spiroheterocyclic Derivativesmentioning

confidence: 99%

Recent Developments in the Stereoselective Synthesis of Nitrogen‐Containing Heterocycles using N‐Acylimines as Reactive Substrates

Marcantoni

Petrini

2016

Adv Synth Catal

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“…The addition may lead to the formation of a β‐silyl‐stabilized carbocation, as perceived through classical silicon chemistry. Although elimination of the silyl group from the carbocation would give allylation product 1 in the classical cascade, it was observed that the cation was intercepted by the nucleophilic oxygen atom to give spirocyclic oxindole intermediate I . This intermediate was isolated, and the structure of its 5,7‐dimethyl analogue 2k was conclusively established by single‐crystal X‐ray analysis.…”

Section: Resultsmentioning

confidence: 99%

Unified Approach to Fused and Spirocyclic Oxindoles through Lewis‐Acid‐Promoted Opening of Spiroepoxyoxindoles with Allylsilanes: Application to the Formal Synthesis of (±)‐Physovenine

et al. 2017

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A protocol for the construction of oxindoles containing all‐carbon quaternary centres in a highly regioselective manner has been developed. The reaction involves opening of spiroepoxyoxindoles with allylsilanes to give Hosomi–Sakurai‐type products as well as new silicon‐containing spirocyclic oxindoles. A formal synthesis of (±)‐physovenine was accomplished in five steps using this protocol.

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“…7; Table 3). Using the tert-butyl-substituted oxindole 1 f leads to trapping of the transient b-silyl carbocation and isolation of the lactone 8 f. [15,22] The yield of 8 f is influenced by the use of chloride versus triflate salt (53 versus 18 % yield, Table 3), which is attributed to Lewis acid initiated deprotection of the tertbutyl ester. The reaction of 1 f using excess NaBArF (60 mol %) promotes allylation with 95 % conversion (in 48 h).…”

Section: Methodsmentioning

confidence: 99%

Catalytic Enantioselective Carboannulation with Allylsilanes

et al. 2014

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The first catalytic asymmetric carboannulation with allylsilanes is presented. The enantioselective [3+2] annulation is catalyzed using a Sc(III)-indapybox complex with tetrakis-[3,5-bis(trifluoromethyl)phenyl]-borate (BArF) to enhance catalytic activity and control stereoselectivity. Functionalized cyclopentanes containing a quaternary carbon are derived from alkylidene oxindole, coumarin, and malonate substrates with high stereoselectivity. The enantioselective 1,4-conjugate addition and enantioselective lactone formation (via trapping of the β-silyl carbocation) is also described.

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Synthesis of Spirocarbamate Oxindoles via Intramolecular Trapping of a β-Silyl Carbocation by an N-Boc Group

Cited by 37 publications

References 63 publications

Recent Developments in the Stereoselective Synthesis of Nitrogen‐Containing Heterocycles using N‐Acylimines as Reactive Substrates

Recent Developments in the Stereoselective Synthesis of Nitrogen‐Containing Heterocycles using N‐Acylimines as Reactive Substrates

Unified Approach to Fused and Spirocyclic Oxindoles through Lewis‐Acid‐Promoted Opening of Spiroepoxyoxindoles with Allylsilanes: Application to the Formal Synthesis of (±)‐Physovenine

Catalytic Enantioselective Carboannulation with Allylsilanes

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