Key words
carbonyl selenation - cyclization - stereoselectivity - heterocycles - macrocycles - (
E)-olefination - regioselective reduction - selenoamide
Woollins’ reagent (W.R.; C12H10P2Se4) is a dark red solid with an unpleasant odor. While this compound poses no inherent risks during handling, it should be stored at approximately 2 °C in an inert environment to maintain its integrity due to its hygroscopic nature.[1a] W.R. has emerged as an analogue to Lawesson’s reagent (LR), both functioning as chalcogen-donating agents for carbonyl compounds, with selenium replacing the oxygen and sulfur in LW.[1b]
[c]
In addition to its role as a selenium donor to carbonyl compounds, W.R. has found applications in various other reactions, including the formation of heterocycles containing phosphorus and/or selenium, macrocycle formation, stereospecific generation of (E)-olefins, and regioselective reduction of unsaturated bonds, among others. The synthesis of the reagent employs recent and optimized methodologies, resulting in a high level of purity and excellent yields (96–99%).[1d]
[e]
It is noteworthy that selenium compounds have diverse applications across various industrial sectors, contributing to their economic value. These applications span multiple fields, such as the pharmaceutical sector,[1`]
[g]
[h] including veterinary pharmacology;[1i] agricultural practices using selenium compounds in fertilizers, pesticides and fungicides;[1j] the synthesis of natural products and their analogs;[1k] modification of the mechanical properties of polymeric materials;[1l] and cosmetics.[1m] Hence, the synthetic exploration of selenium-derived compounds assumes increasing importance and necessity.
Figure 1 Formation of Woollins’ reagent and carbonyl selenylation
Figure 2 Formation of heterocycles containing selenium, nitrogen, and oxygen atoms
Figure 3 Chemoselective reduction of conjugated 1,4-dicarbonyl compounds, stereoselective synthesis of (E)-olefins by a reductive coupling reaction and the respective mechanistic proposals
Figure 4 Preparation of heterocycles containing phosphorus, and the formation of macrocyclic compounds along with mechanistic proposals
Figure 5 Selenoic acid formation, sulfoxide reduction (with a mechanistic proposal), hydrogen replacement and organometallic transformations/formation
Figure 6 Natural product applications
