A Biphilic Phosphetane Catalyzes N–N Bond-Forming Cadogan Heterocyclization via P[superscript III]/P[superscript V]═O Redox Cycling
A small-ring phosphacycle, 1,2,2,3,4,4-hexamethylphosphetane, is found to catalyze deoxygenative N-N bond-forming Cadogan h eterocyclization of o-nitrobenzaldimines, o-nitroazobenzenes, and related substrates in the presence of hydrosilane terminal reductant. The reaction provides a chemoselective c...
| Main Authors: | , , , , |
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| Other Authors: | |
| Format: | Article |
| Published: |
American Chemical Society (ACS)
2018
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| Online Access: | http://hdl.handle.net/1721.1/116319 https://orcid.org/0000-0002-7683-2984 https://orcid.org/0000-0003-3786-0453 |
| Summary: | A small-ring phosphacycle, 1,2,2,3,4,4-hexamethylphosphetane, is found to catalyze deoxygenative N-N bond-forming Cadogan h eterocyclization of o-nitrobenzaldimines, o-nitroazobenzenes, and related substrates in the presence of hydrosilane terminal reductant. The reaction provides a chemoselective catalytic synthesis of 2H-indazoles, 2H-benzotriazoles, and related fused heterocyclic systems with good functional group compatibility. On the basis of both stoichiometric and catalytic mechanistic experiments, the reaction is proposed to proceed via catalytic P[superscript III]/P[superscript V] = O cycling, where DFT modeling suggests a turnover-limiting (3+1) cheletropic addition between the phosphetane catalyst and nitroarene substrate. Strain/distortion analysis of the (3+1) transition structure highlights the controlling role of frontier orbital effects underpinning the catalytic performance of the phosphetane. |
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