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. 2020 May 12;5(20):11737-11744.
doi: 10.1021/acsomega.0c01064. eCollection 2020 May 26.

Novel Five- and Six-Membered Rings of Phosphorus-Selenium Heterocycles from Selenation of Amido-Schiff Bases

Guoxiong Hua  1 , David B Cordes  1 , Alexandra M Z Slawin  1 , J Derek Woollins  1   2
Affiliations

Novel Five- and Six-Membered Rings of Phosphorus-Selenium Heterocycles from Selenation of Amido-Schiff Bases

Guoxiong Hua et al. ACS Omega. .

Abstract

Woollins' reagent, [2,4-bis(phenyl)-1,3-diselenadiphosphetane-2,4-diselenide], serving as a selenating-reductive cycloaddition reagent, reacts with nonconjugated amido-Schiff bases to give the corresponding six-membered 1,3,4-selenadiazoles via a ring-expansion accompanied by an additional selenation/cyclization to the imine bond and C=O group; meanwhile, under the same reaction conditions, the selenation of conjugated amido-Schiff bases leads to a series of fused heterocycles with two five-membered rings. Eight single-crystal X-ray structures confirming the formation of these five- and six-membered heterocycles are discussed.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Scheme 1
Scheme 1. Synthesis of the Six-Membered Phosphorus–Selenium Heterocycles 3 and 4
Scheme 2
Scheme 2. Formation of the Heterocyclic Compounds 6 and 7
Scheme 3
Scheme 3. Preparation of the Fused Five-Membered Rings 9a–d
Scheme 4
Scheme 4. Preparation of the Five-Membered Ring 11
Figure 1
Figure 1
X-ray structure of compound 3, with hydrogen atoms omitted for clarity.
Figure 2
Figure 2
X-ray structure of compound 4, with hydrogen atoms omitted for clarity.
Figure 3
Figure 3
X-ray structure of compound 6, with hydrogen atoms omitted for clarity.
Figure 4
Figure 4
X-ray structure of compound 7, with hydrogen atoms omitted for clarity.
Figure 5
Figure 5
X-ray structure of compound 9a, with hydrogen atoms omitted for clarity.
Figure 6
Figure 6
X-ray structure of compound 9c, with hydrogen atoms omitted for clarity.
Figure 7
Figure 7
X-ray structure of compound 9d, with hydrogen atoms omitted for clarity.
Figure 8
Figure 8
X-ray structure of compound 11, with hydrogen atoms omitted for clarity.
See this image and copyright information in PMC

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