Radical-based reduction of phosphine sulfides and phosphine selenides by (Me3Si)3SiH

(Me3Si)3SiH: Twenty Years After Its Discovery as a Radical‐Based Reducing Agent

“…[20] A C H T U N G T R E N N U N G (Me 3 Si) 3 SiH is useful for the reduction of phosphine sulfides and phosphine selenides under free radical conditions to give the corresponding phosphines or, after treatment with BH 3 ·THF, the corresponding phosphine-borane complex in good to excellent yields. [21] Stereochemical studies on P-chiral phosphine sulphides have shown that these reductions proceed with retention of configuration. This desulfidation protocol has recently been applied with success for the synthesis of bulky phosphines (e.g., Scheme 3) [22] or (Z)-1,2-diphosphino-1-alkenes.…”

New Monodentate P,C‐Stereogenic Bicyclic Phosphanes: 1‐Phenyl‐1,3a,4,5,6,6a‐hexahydrocyclopenta[b]phosphole and 1‐Phenyloctahydrocyclopenta[b]phosphole

“…The analogous annulation with 1-phenyl-2,5-dihydro-1H-phosphole 1-sulfide proved to be less exothermic and afforded the expected 1-phenyl-1,3a,4,5,6,6a-hexahydrocyclopenta[b]phosphole 1-sulfide (7) in very high yield irrespective of the reaction scale used (91% yield for a 10 mmol scale). [5,6] Reduction of 6 with phenylsilane [7] and radical-based reduction of 7 with tris(trimethylsilyl)silane [8] gave 1-phenyl-1,3a,4,5,6,6a-hexahydrocyclopenta[b]phosphole (4) quantitatively and with complete retention of configuration at P (Scheme 1). [5,7,8] Scheme 1.…”

“…[5,6] Reduction of 6 with phenylsilane [7] and radical-based reduction of 7 with tris(trimethylsilyl)silane [8] gave 1-phenyl-1,3a,4,5,6,6a-hexahydrocyclopenta[b]phosphole (4) quantitatively and with complete retention of configuration at P (Scheme 1). [5,7,8] Scheme 1. Synthesis of racemic 1-phenyl-1,3a,4,5,6,6a-hexahydrocyclopenta [b]phosphole (4) Separation of 4 into its enantiomers was achieved by an oxidative resolution route, [9] as shown in Scheme 2.…”

Recent Applications of the (TMS)3SiH Radical-Based Reagent

“…(TMS) 3 SiH is also useful for the reduction of nitroxides to secondary amines [ 16 ] and of phosphine sulfides and phosphine selenides to give the corresponding phosphines [ 17 , 18 ]. Several radical-based reductions with (TMS) 3 SiH have been expanded towards technological applications.…”