Modular Functionalization of Allenes to Aminated Stereotriads

Adams, Christopher S.; Boralsky, Luke A.; Guzei, Ilia A.; Schomaker, Jennifer M.

doi:10.1021/ja304859w

Cited by 85 publications

(26 citation statements)

References 38 publications

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“…We previously leveraged the unusual strain (~42 kcal/mol) in methyleneaziridine 1a to achieve a formal [3+1] reaction to furnish methyleneazetidine 1d upon exposure to rhodium-supported carbene 1b ( Fig. 2a) [55][56][57][58][59][60][61][62] . Mechanistic studies support initial formation of the aziridinium ylide 1c, which subsequently undergoes a highly asynchronous, concerted [2,3]-Stevens rearrangement to form 1d 63 .…”

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Intermolecular [3+3] ring expansion of aziridines to dehydropiperi-dines through the intermediacy of aziridinium ylides

et al. 2020

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The importance of N-heterocycles in drugs has stimulated diverse methods for their efficient syntheses. Methods that introduce significant stereochemical complexity are attractive for identifying new bioactive amine chemical space. Here, we report a [3 + 3] ring expansion of bicyclic aziridines and rhodium-bound vinyl carbenes to form complex dehydropiperidines in a highly stereocontrolled rearrangement. Mechanistic studies and DFT computations indicate that the reaction proceeds through formation of a vinyl aziridinium ylide; this reactive intermediate undergoes a pseudo-[1,4]-sigmatropic rearrangement to directly furnish heterocyclic products with net retention at the new CC bond. In combination with asymmetric silver-catalyzed aziridination, enantioenriched scaffolds with up to three contiguous stereocenters are rapidly delivered. The mild reaction conditions, functional group tolerance, and high stereospecificity of this method are well-suited for appending piperidine motifs to natural product and complex molecules. Ultimately, our work establishes the value of underutilized aziridinium ylides as key intermediates for converting small, strained rings to larger N-heterocycles.

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Intermolecular [3+3] ring expansion of aziridines to dehydropiperi-dines through the intermediacy of aziridinium ylides

et al. 2020

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“…In our previous work, aziridination and subsequent functionalization of enantioenriched allenes gave excellent transfer of axial to point chirality ,. However, the intermediacy of an amidoallyl cation in the [4+3] precludes chirality transfer (see the Supporting Information).…”

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Stereocontrolled Syntheses of Seven‐Membered Carbocycles by Tandem Allene Aziridination/[4+3] Reaction

et al. 2016

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A tandem allene aziridination/[4+3]/reduction sequence converts simple homoallenic sulfamates into densely functionalized aminated cycloheptenes, where the relative stereochemistry at five contiguous asymmetric centers can be controlled through the choice of the solvent and the reductant. The products resulting from this chemistry can be readily transformed into complex molecular scaffolds which contain up to seven contiguous stereocenters.

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“…A methodology to prepare stereotriads containing three contiguous heteroatom-bearing carbons of the general pattern X/N/Y has been developed. 72 This transformation involves a Rh-catalyzed intramolecular conversion of an allenic sulfamate 96 into a highly reactive methylene aziridine, which in the presence of a nucleophile underwent regioselective ring-opening to yield the Eenesulfamate 97 exclusively in 61% yield and 99% ee (Scheme 40). Pauson-Khand reaction involving an allene moiety is an excellent strategy to give cyclopentenones.…”

Section: Metal-catalyzed or Metal-promoted Cyclizationsmentioning

confidence: 99%