Oxidation reactions of phosphaalkenes

Phosphaorganische Chemie: Panorama und Perspektiven

“…Die sehr schmale Energielücke zwischen dem π‐ und dem n P ‐Orbital führt dazu, dass elektrophile Reagentien häufig wahllos an der CP‐Bindung oder dem freien Elektronenpaar am Phosphoratom angreifen werden, z. B. bei Oxidationen43a oder Sulfidierungen 44. Phosphoroxide sind meist instabil und lassen sich nur isolieren, wenn das Phosphoratom hinreichend sterisch geschützt ist 43b.…”

Unexpected Thermal Reactivity of Phosphirano‐[1,2]thiaphosphole P–W(CO)5 Complexes

“…When a solution of freshly prepared 13 was in contact with air, it was consumed quantitatively within 1 min ( 31 P NMR control). Column chromatography allowed the separation of fluorenylidenepropanone 14 (80 % yield) from tributylphosphane sulfide and a fraction, which according to the 31 P chemical shifts, was a mixture of the known [23] [24] however, it may be assumed that 13 initially reacts with oxygen to undergo an oxidative cleavage via a 1,2,3-dioxaphosphetane. The details of the loss of the [P(=O) W(CO) 5 ] fragment from the ring-opened intermediate are unknown.…”

Reductive coupling of two aldehydes to unsymmetrical E-alkenes via phosphaalkene and phosphinate intermediates

“…This reactivity trend is thus similar to that observed for hydroxide attack at phosphaalkenes in step 2.1, and the reason for using electron-deficient aldehydes in the first step of the synthetic sequence. Conversion of phosphinite 8 to phosphinate 9 can be achieved by a variety of oxidants, 31 with t-BuOOH giving the most satisfying results. An aqueous hydrogen peroxide solution can also be used, however, has been found to hydrolyze substituents such as cyanides that may be present in the compound.…”

“…Noteworthy is also the coupling of 4-cyano-with 4-nitrobenzaldehyde to the unsymmetric stilbene in 67% yield (entry 7), as neither of the substrates are compatible with the radical mechanism of the McMurry coupling. 19,34 As mentioned above, 31 P NMR spectroscopy is a convenient tool to follow all steps of the sequence. As shown in Fig.…”

“…31 P NMR spectroscopic investigations of individual reaction steps. Deprotonation of phosphanylphosphonate 1-H to…”