Intramolecular C(sp³)N Coupling by Oxidation of Benzylic C,N‐Dianions

Abstract

What a couple! An intramolecular, C(sp3)N coupling to afford azacycles is reported. This reaction proceeds through the oxidation of benzylic C,N‐dianions with iodine and builds on an earlier discovery during the synthesis of the natural product lyconadin A. The current study employs conformationally unbiased substrates with less acidic CH bonds and less reactive nitrogen nucleophiles. ZnCl2 was identified as an important additive.

Rhodium-catalysed tetradehydro-Diels–Alder reactions of enediynes via a rhodium-stabilized cyclic allene

“…Other protecting groups on N were not investigated due to the established instability of isoindolines without an electronwithdrawing N group. [23][24][25][26][27] Finally, a carbon-tethered enediyne 1u was prepared and found to undergo smooth cycloaromatisation to trisubstituted indane 2u.…”

Dual Gold‐Catalyzed Cycloaromatization of Unconjugated (E)‐Enediynes

“…This observation is potentially due to auto-oxidation, which has been previously observed with these heterocycles. [17,18] Running the reaction at lower temperatures in DCE led to the detection of unstable intermediate 8 as a( Z/E)m ixture, [19] providing some indication that askeletal, rather than adualgold mechanism might be one potential pathway operating for the propargyl enediyne substrates,a si ntermediates 8 are setup to form the isoindole heterocycles via am ono-goldcatalyzed cycloaromatization process. [20] These results indicate that the propiolic amide is important for generating astable organic product and, as explained below,likely assists in favoring the proposed dual-gold mechanism.…”

Visible‐Light‐Catalyzed Direct Benzylic C(sp3)–H Amination Reaction by Cross‐Dehydrogenative Coupling

“…Apart from using metal/organo nitrenoids, another interesting methodology in this area is reported by directed metal-catalyzed inter-and intramolecular amination of CÀHb onds. [8] However,u se of ad irecting group as an appendage limits its scope.Efforts have also been directed to replace costly transition metals in C-H amination reactions by developing catalytic cross-dehydrogenative couplings (CDC) using more environmental friendly metal salts [9,10] or metal-free conditions, [11] but these strategies require strong oxidizing agents.R adical-based cross-coupling reactions [12] are also reported in this area but selectivity remains the main issue in these approaches.Sarpong and co-workers have reported an interesting strategy for intramolecular nitrogen incorporation by oxidation of ab enzylic C,N-di-anion using iodine as an oxidant [13] but the major constraint of this strategy remains functional group tolerance owing to the use of an excess of strong base.…”