Insertion of Arynes into N-Halo Bonds: A Direct Approach to o-Haloaminoarenes

Abstract

A new approach to access o-haloaminoarenes has been achieved by insertion of arynes into a nitrogen–halide bond (N–X). This transition-metal-free transformation displays a broad substrate scope of arynes, good compatibility with functional groups, and high regioselectivity. Representative transformations of the o-haloaminoarenes are described to highlight their utility for rapid access to diversely functionalized aminoarene derivatives.

Regioselective Synthesis of 1,2,3,4‐Tetrasubstituted Arenes by Vicinal Functionalization of Arynes Derived from Aryl(Mes)iodonium Salts**

“…Arynes are known to formally insert into σ‐bonds and these reactions are likely initiated by nucleophilic properties of the arynophile and electrophile properties of the aryne. Along these lines the N ‐Cl σ‐bond of 2 h is cleaved and a new C−N and C−Cl bonds are formed in 3 bh (Table 3, 56 %), and similar reactivity is observed with 2 i [30] . Finally, the N−Si bond is cleaved in 2 j and new C−N and C−Si bonds are formed in 3 dj (Table 3, 41 %) [31] .…”

“…Along these lines the N-Cl sbond of 2h is cleaved and an ew CÀNa nd CÀCl bonds are formed in 3bh (Table 3, 56 %), and similarr eactivity is observed with 2i. [30] Finally,t he NÀSi bond is cleaved in 2j and new CÀN and CÀSi bonds are formed in 3dj (Table 3, 41 %). [31] We reiterate at this juncture that the products described in Ta ble 2a nd 3a re distinct from those obtained from Pd-norbornene (Catel- lani)c hemistry as ar esult of distinct mechanisms and therefore represent complementary strategies to highlys ubstituted arene cores.…”

Microflow Fluorinations of Benzynes: Efficient Synthesis of Fluoroaromatic Compounds

“…In this case, the regiochemistry is believed to be mainly controlled by the steric bulkiness of the C3-silyl group of 4f. 68) Despite extensive examples in the literature involving the reactions of halobenzynes with a range of arynophiles, [79][80][81][82][83][84][85][86][87][88][89][90][91][92] the nucleophilic fluorination of halobenzynes 4h-4k, generated from 3h, 3i, 3j′, and 3k′, with Bu 4 NF(t-BuOH) 4 under normal batch conditions produced complex mixtures, and the yields of the expected fluorobenzenes 1 were very poor ( Table 3). In stark contrast, the reaction of 5-chloro-3-(tertbutyldimethylsilyl) benzyne (4h), generated from 3h, with Bu 4 NF(t-BuOH) 4 under the optimized flow conditions produced 1h in 51% yield as a mixture of two regioisomers (meta-1h/ortho-1h=1.2 : 1, Entry 1).…”

A Straightforward Synthesis of α‐Amino Diaryl Ketones from (Hetero)Arylacetonitriles Promoted by N‐Bromosuccinimide

“…Further, 2‐bromo‐1,2‐diphenylethanone 6 was treated with morpholine, which afforded the α ‐amino ketone 3 a in 89% yield (Scheme b). Based on these outcomes, we anticipated that N ‐bromomorpholine 7 (in situ generated in reaction with NBS and morpholine), might be the real brominating agent in this transformation. To verify this, we conducted few additional experiments.…”