Three‐Component Assembly and Divergent Ring‐Expansion Cascades of Functionalized 2‐Iminooxetanes

Abstract

Eine CuI‐katalysierte Mehrkomponentenreaktion verknüpft aromatische Alkine, p‐Toluolsulfonylazid und aromatische 2‐Oxobut‐3‐inoate zu den funktionalisierten 2‐Iminooxetanen I, die selektiv in zweierlei fünfgliedrige Stickstoffheterocyclen umgewandelt werden konnten (siehe Schema; Tf=Trifluormethansulfonyl; R=Et, iPr).

An Organocatalytic Cascade Approach toward Polysubstituted Quinolines and Chiral 1,4‐Dihydroquinolines–Unanticipated Effect of N‐Protecting Groups

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Organocatalytic cascade reactions have been established as a viable and efficient approach to complex molecular architectures, [1] however, examples of the combination of powerful divergent synthesis with an organocatalytic cascade strategy are rare. [2] Herein, we report a powerful divergent organocatalytic cascade reaction that proceeds via a chiral allenamine [3] and involves unprecedented aza-Michael/aldol and aza-Michael/aldol/aromatization sequences to give chiral 1,4-dihydroquinolines and quinolines, respectively. Notably, we made the unexpected discovery that the type of product that is formed depends on the nature of the N-protecting group of the starting material.

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“…Both substrates, ynals 1 and aminoketones 5, can be tolerated with significant structural variations. The electronic and steric factors associated with the a,b-unsaturated ketone moieties of 2'-(trifluoromethanesulfonyl)aminochalcones 5 appeared to have minimal impact on the reaction efficiencies with regard to enantioselectivity and yields ( Table 4, entries [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The electronic effect of ynals 1 also influences the reaction rate.…”

An Organocatalytic Cascade Approach toward Polysubstituted Quinolines and Chiral 1,4‐Dihydroquinolines–Unanticipated Effect of N‐Protecting Groups

“…

Organocatalytic cascade reactions have been established as a viable and efficient approach to complex molecular architectures, [1] however, examples of the combination of powerful divergent synthesis with an organocatalytic cascade strategy are rare. [2] Herein, we report a powerful divergent organocatalytic cascade reaction that proceeds via a chiral allenamine [3] and involves unprecedented aza-Michael/aldol and aza-Michael/aldol/aromatization sequences to give chiral 1,4-dihydroquinolines and quinolines, respectively. Notably, we made the unexpected discovery that the type of product that is formed depends on the nature of the N-protecting group of the starting material.

…”