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

Abstract

Woollins' reagent, [2,-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 fivemembered rings. Eight single-crystal X-ray structures confirming the formation of these fiveand six-membered heterocycles are discussed.

Selenium‐NMR Spectroscopy in Organic Synthesis: From Structural Characterization Toward New Investigations

“…In 2020, Woollins and co‐workers employed Woolins’ reagent [2,4‐bis(phenyl)‐1,3‐diselenadiphosphetane‐2,4‐diselenide] to perform a cycloaddition reaction with nonconjugated amido‐Schiff bases to provide the corresponding six‐membered 1,3,4‐selenadiazoles or fused heterocycles with two five‐membered rings (Scheme 16). [101] The Woolins’ reagent is a very useful selenation agent which result in very functionalized products, whereby the 77 Se NMR spectroscopy is an imperative tool to confirm the structural elucidation. In this manuscript, the library of products was prepared, using 77 Se{ 1 H} NMR experiments to identify the phosphorus‐selenium heterocycles (Scheme 16) together with other analyses, as X ‐ray diffraction, IR, and HRMS.…”

Research Progress on Quercetin's Biological Activity and Structural Modification Based on Its Antitumor Effects

“…The carbonyl group was efficiently transformed into a selenocarbonyl group using 2,4-bis(phenyl)-1,3-diselenodiphosphine-2,4-diselenide (Woollins' Reagent, WR) as the selenium source, producing Compound 12 c. However, deprotection of selenium Compound 12 c did not result in Compound 12 e, as shown in Scheme 12. [74] Martins et al [75] utilized the MTT method to test the inhibitory effects of three quercetin sulfur or selenium carbonyl compounds on tumor cell proliferation. Human colorectal adenocarcinoma HCT-15, MCF-7, multidrug-resistant MCF-7-ADR, and human cervical cancer A431 cells were evaluated for their activity.…”

“…To obtain Compound 12 d, Compound 12 b was placed in a dichloromethane solution containing excess boron tribromide and reacted at room temperature to remove the protecting group. The carbonyl group was efficiently transformed into a selenocarbonyl group using 2,4‐bis(phenyl)‐1,3‐diselenodiphosphine‐2,4‐diselenide (Woollins′ Reagent, WR) as the selenium source, producing Compound 12 c. However, deprotection of selenium Compound 12 c did not result in Compound 12 e, as shown in Scheme 12 [74] …”

Organo Phosphorus‐Sulfur‐Nitrogen Heterocycles from Thionation of Schiff Bases

“…Recently, we have reported the selenation of Schiff bases by Woollins' reagent leading to a series of phosphorus‐selenium heterocycles. [ 13,14 ] The chemistry of dithiadiphosphetane disulfides has been the subject of several reviews, articles and communications. [ 15 ] In the continuation of our interest in the chemistry of sulfur‐phosphorus heterocycles, we report here the reactivity of 2,4‐diferrocenyl‐1,3,2,4‐diathiadiphosphetane 2,4‐disulfide ( FcLR , a ferrocene analogue of Lawesson's reagent) toward amido‐Schiff bases and simple imine, and six single‐crystal X‐ray structures.…”