One‐pot Annulation for Biaryl‐fused Monocarba‐closo‐dodecaborate through Aromatic B−H Bond Disconnection

Abstract

We have developed a one-pot annulation reaction of monocarba-closo-dodecaborate with cyclic diaryliodonium salts to afford biaryl-fused derivatives. Aryl functionalities are introduced at both the 1-carbon and unreactive ortho-boron vertices of the "σ-aromatic" carborane cage without the need for pre-functionalization. DFT calculations revealed that the palladium-catalyzed C-B bond-formation step in this process proceeds through a concerted metalation-deprotonation (CMD)-type pathway for the B-H bond disconnection on the aromatic cage, though such bonds are generally regarded as hydridic.

Copper‐Catalyzed Diphenylation of P(O)‐OH Bonds with Cyclic Diaryliodonium Salts

“…The collected solid was washed with Et 2 O three times, dried in vacuo to afford 1 a (1.68 g, 98 % yield) as a white powder. Compounds of 1 b – m were synthesized by the general procedure A , B , C. 1 a (yield: 81 %), 1 b (yield: 75 %), 1 c (yield: 69 %), 1 d (yield: 43 %), 1 e (yield: 65 %), 1 f (yield: 46 %), 1 g ((yield: 60 %), 1 i ((yield: 71 %), 1 j ((yield: 68 %), 1 l ((yield: 36 %), 1 m ((yield: 77 %), 1 h (yield: 29 %) and 1 k (yield: 55 %) are new compounds.…”

Recent Progress in the Synthesis of the Monocarba‐closo‐dodecaborate(−) Anions

“…As am ethod of BÀHa ctivation without using directing groups,w er ecently developed ap alladium catalyzed annulation reaction (Scheme 10). [23] We reported an annulation reaction of 1 to obtain aw ide range of 1,2-biaryl-fused derivatives 33 via 1-C-arylated derivatives 32.T his reactioni st he first example of selectiveC ÀB bond formation at the B2 vertex withoutu sing any directing group. The structure of the 1,2-biaryl-fused product 33 d was determined by X-ray crystallographic analysis(Scheme1 1).…”

“…As a method of B−H activation without using directing groups, we recently developed a palladium catalyzed annulation reaction (Scheme ) …”

“…This reaction is the first example of selective C−B bond formation at the B2 vertex without using any directing group. The structure of the 1,2‐biaryl‐fused product 33 d was determined by X‐ray crystallographic analysis (Scheme ) …”

“…The structure of the 1,2-biaryl-fused product 33 d was determined by X-ray crystallographic analysis(Scheme1 1). [23] Thus, it has become possible to synthesize relatively complicated C1 carborane anion derivatives. Further progress in the development of B7-12 selective BÀHa ctivation can be expected.…”