期刊
ORGANIC CHEMISTRY FRONTIERS
卷 8, 期 13, 页码 3238-3243出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/d1qo00305d
关键词
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资金
- National Natural Science Foundation of China [U2004189]
- Program for Innovative Research Team in Science and Technology in the Universities of Henan Province [20IRTSTHN005]
- Natural Science Foundation of Henan Province [212300410364]
- 111 Project [D17007]
A novel synthesis of pyrazolidinone fused 1,3-benzooxazepine derivatives via a formal [4 + 3] annulation reaction of 1-phenylpyrazolidinones with diazonaphthalen-2(1H)-ones is presented. The mechanism involves an unprecedented reaction mode of 1-phenylpyrazolidinone, featuring cascade C-alkylation/C-annulation through C(sp(2))-H/C(sp(3))-H bond cleavage. Compared with literature methods, this protocol offers advantages such as easily accessible starting materials, structurally complex and biologically attractive products, a unique mechanistic pathway, and excellent chemo/regioselectivity.
Herein, a novel synthesis of pyrazolidinone fused 1,3-benzooxazepine derivatives via a formal [4 + 3] annulation reaction of 1-phenylpyrazolidinones with diazonaphthalen-2(1H)-ones is presented. Mechanistically, the formation of products involves an unprecedented reaction mode of 1-phenylpyrazolidinone featuring cascade C-alkylation/C-annulation through C(sp(2))-H/C(sp(3))-H bond cleavage instead of C-alkylation/N-annulation via C(sp(2))-H/N-H bond cleavage as reported in previous studies on the reaction of 1-phenylpyrazolidinone. In this cascade process, the pyrazolidinone unit firstly acts as an embedded directing group to assist in the alkylation and subsequently it is transformed into a cyclic iminium species to undergo an intramolecular nucleophilic addition with the in situ formed naphthol unit to give the polycyclic product. Compared with literature methods for the preparation of N-fused 1,3-oxazepines, the protocol developed herein has advantages such as easily accessible starting materials, structurally complex and biologically attractive products, a unique mechanistic pathway, and excellent chemo/regioselectivity.
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