A metal-free oxidative tandem coupling of activated alkenes with carbonyl C(sp 2 )-H bonds and aryl C(sp 2 )-H bonds using TBHP is established for the synthesis of 3-(2-oxoethyl)indolin-2-ones. This method allows 1,2-difunctionalization of the C-C double bond in N-arylacrylamides by simultaneous formation of two C(sp 2 )-C(sp 3 ) bonds. Scheme 1 Oxidative tandem coupling reaction. Scheme 2 Utilization of 3-(2-oxoethyl)indolin-2-ones.
A new, efficient Cu-catalyzed intramolecular C-H oxidation/acylation method has been developed for the synthesis of substituted indoline-2,3-diones (isatins). In the presence of CuCl(2) and O(2), a variety of formyl-N-arylformamides underwent the tandem reaction to afford the corresponding indoline-2,3-diones in moderate to good yields. It is noteworthy that the reaction serves as the first example of transition-metal-catalyzed transformation for the preparation of indoline-2,3-diones.
A new metal-free oxidative radical [2+2+1] carbocyclization of benzene-linked 1,n-enynes with two C(sp(3))-H bonds adjacent to the same heteroatom is described. This method achieves two C(sp(3))-H oxidative functionalizations and an annulation, thus providing efficient and general access to a variety of fused five-membered carbocyclic hydrocarbons.
Here we describe the one-pot construction of the pyrrolo[4,3,2-de]quinolinone scaffold by a cascade nitration/cyclization sequence of 1,7-enynes with tBuONO and H2O. The cascade proceeds through alkene nitration, 1,7-enyne 6-exo-trig cyclization, C-H nitrations, and redox cyclization, and exhibits excellent functional group tolerance. The mechanism was investigated using in situ high-resolution mass spectrometry (HR-MS).
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