New synthetic routes to C-amino phosphorus ylides and their subsequent fragmentation into carbenes and phosphines.

Phosphonio-substituted aldiminium, iminium, and imidazolidinium salts are readily prepd. by the addn. of phosphines to the Alder dimer or by treatment of the corresponding chloroiminium salt with the phosphine/trimethylsilyl triflate adduct generated in situ. Redn. with either K metal or tetrakis(dimethylamino)-ethylene leads to the corresponding C-amino P ylides. When basic phosphine fragments were used, the ylides can be isolated; otherwise they fragment into the carbene and phosphine. This method is limited to the prepn. of transient carbenes, owing to the unavailability of sterically hindered dications, and consequently of P ylides with bulky C substituents. This difficulty is overcome by the addn. of 2,4-di-tert-butyl-ortho-quinone to readily available C-amino phosphaalkenes at low temp. Provided the P atom bears either an amino or tert-Bu group, [4 + 1] cycloaddn. occurs, and the resulting ylides fragment into a dioxaphospholane and a spectroscopically obsd. carbene. [on SciFinder(R)]

Références

Titre
New synthetic routes to C-amino phosphorus ylides and their subsequent fragmentation into carbenes and phosphines.
Type de publication
Article de revue
Année de publication
2006
Revue
Chem. - An Asian J.
Volume
1
Pagination
155–160
ISSN
1861-4728
Soumis le 21 janvier 2019