Synthesis of triphenylene-fused phosphole oxides via C-H functionalizations.

Md Shafiqur Rahman,Naohiko Yoshikai

doi:10.3762/bjoc.16.48

Md Shafiqur Rahman, Naohiko Yoshikai

Open Access

https://doi.org/10.3762/bjoc.16.48

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Abstract

The synthesis of triphenylene-fused phosphole oxides has been achieved through two distinct C–H functionalization reactions as key steps. The phosphole ring was constructed by a three-component coupling of 3-(methoxymethoxy)phenylzinc chloride, an alkyne, and dichlorophenylphosphine, involving the regioselective C–H activation of the C2 position of the arylzinc intermediate via 1,4-cobalt migration. The resulting 7-hydroxybenzo[b]phosphole derivative was used for further π-extension through Suzuki–Miyaura couplings and a Scholl reaction, the latter closing the triphenylene ring. The absorption and emission spectra of the thus-synthesized compounds illustrated their nature as hybrids of triphenylene and benzo[b]phosphole.

Highlights

The phosphorus-containing five-membered ring, phosphole, has attracted significant attention as a structural motif in π-conjugated functional molecules [1,2,3,4,5,6,7,8,9]
With the phosphole-fused ortho-teraryl compounds 7 in hand, we examined their cyclization into triphenylene derivatives by the Scholl reaction (Scheme 3) [30]
The phosphole ring was constructed in the early stage of the synthesis by a three-component assembly method featuring a 1,4-cobalt migration as the key step

Summary

Introduction

The phosphorus-containing five-membered ring, phosphole, has attracted significant attention as a structural motif in π-conjugated functional molecules [1,2,3,4,5,6,7,8,9]. The synthesis of PAH-fused phospholes typically requires efficient methods for the construction of the phosphole ring as well We have recently reported the synthesis of novel phosphahelicenes that featured angular fusion of the phosphole and the carbohelicene moieties (Scheme 1) [16].

Results

Conclusion