We report herein a convenient and scalable dearomative hydroacylation reaction of indoles. Employing readily available aldehydes as the acyl source and TBADT as an inexpensive direct HAT photocatalyst, a variety of indoles derivatives were converted into synthetically interesting 2acylindolines in good to excellent yields as well as great diastereoselectivity under mild conditions. An asymmetric version of the reaction was successfully developed and an experimental mechanistic investigation was carried out in order to gain further insights on the assumed reaction pathway.
Highly enantio-and regioselective selective (3 + 2) formal cycloaddition of b-substituted ene-and thioenecarbamates as well as cyclic enamides with quinone diimides catalyzed by a BINOL-and SPINOL-derived phosphoric acid has been reported. A wide variety of 2-amino 2,3-disubtituted indolines, including polycyclic ones, were prepared in generally high yields (up to 98%) with moderate to complete diastereoselectivities and in most cases excellent enantioselectivities (up to 99% ee).Chiral 2,3-disubstituted indolines are privileged heterocyclic rings frequently encountered in various natural bioactive alkaloids (such as (-)-physostigmine, (+)-aspidospermidine and pircrinine, Figure 1) 1 and biologically active drugs (such as pentopril and relcovaptan). 2 In addition, they have been successfully employed as chiral auxiliaries and organocatalysts in asymmetric synthesis. 3 As a result, several asymmetric catalytic approaches have been established for the construction of indoline rings. 4 Despite these elegant achievements, the development of novel asymmetric synthetic routes of 2,3disubstituted indolines is still highly desirable.
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