Diamination/Oxidative Cross-Coupling/Bicyclization of Anilines and Methyl Ketones: Direct I₂-Promoted Synthesis of 1,2-Fused Oxindoles

Abstract

An I-promoted domino bicyclization approach via multiple sequential C-H functionalization was serendipitously discovered for the synthesis of 1,2-fused oxindoles from methyl ketones and anilines. This approach was optimized, resulting in a concise and atom-economical approach for the one-pot construction of 1,2-fused oxindoles from methyl ketones and anilines rather than using preexisting indolin-3-ones or indoles. Mechanistic studies revealed that the key step involved an oxidative cross-coupling between in situ generated phenylglyoxal and α,α-diaminoketone.

Iodine-DMSO mediated conversion of N-arylcyanothioformamides to N-arylcyanoformamides and the unexpected formation of 2-cyanobenzothiazoles

“…On the other hand, the iodine/DMSO oxidation system has truly revolutionized synthetic practices in a plethora of reactions involving oxidation processes. 43–56 This oxidant has been particularly used in C–N bond chemistry as a greener solution to existing conventional synthetic methodologies and to avoid employing harsh, toxic, and expensive metals and reagents. The wide and abundant availability of iodine and DMSO, ease of preparation, moisture and air stability, atom and step economy, as well as its environmentally benign nature render such system very convenient.…”

Acid‐Acid‐Catalyzed Tandem Reactions Driven by an Additive‐Like Component

“…[31] Like NBS, molecular iodine can also assist some oxidative processes, such as the well-known Kornblum oxidation. [32] In view of these excellent performances, molecular iodine was quite often used by organic chemists as a kind of cheap and irreplaceable additive-like component to establish some catalytic systems. Particularly, the combination of I 2 and acid catalyst contributed many interesting tandem reactions.…”

Convenient Synthesis of Acyclic Amidines via Copper‐Catalyzed C(sp3)‐H Amidination

“…Moreover, only one C(sp 3 )–H bond amidination was yielded. The effective examples of three C(sp 3 )–H bond amidination were also reported, it include: 1) copper, manganese or ferrite‐catalyzed amidination of methyl C(sp 3 )–H bonds of acetophenone or toluenes with o‐phenylenediamine in the synthesis of benzo[ d ]imidazoles (Scheme a‐b); 2) copper or metal‐free catalyzed C(sp 3 )–H amidination of (2‐azaaryl)methanes, acetophenones or toluenes with 2‐aminobenzamides in the synthesis of quinazolinones (Scheme c‐e); 3) copper or metal‐free catalyzed C(sp 3 )–H amidination of acetophenones with p ‐substituted anilines or secondary amines affording 1,2‐fused oxindoles or 2‐oxo‐acetamidines as final products (Scheme f and 1 g). These protocols are promising and very attractive strategy to synthesize a wide range of N‐heterocycles via C(sp 3 )‐H amidination.…”