P=N Bond Formation
Recent Literature
Under iron catalysis, a hydroxylamine-derived triflic acid salt oxidizes
phosphines to a wide range of iminophosphorane triflic acid salts. Diphosphines
afford phosphine-iminophosphoranes that can serve as ligands in transition metal
complexes. The developed method can be employed in the synthesis of mixed
diiminophosphoranes and in a traceless Staudinger ligation.
E. Falk, A. Franchino, T. Horak, L. Gürtler, B. Morandi, Org. Lett., 2023, 25,
1695-1700.
FeCl2 catalyzes a facile imidization of phosphines with N-acyloxyamides
to provide synthetically useful N-acyliminophosphoranes with high
functional group tolerance. The transformation can be scaled up to gram scale
with a catalyst loading of 1 mol%. The iminophosphoranyl moiety is an effective
directing group for Rh(III)-catalyzed ortho C(sp2)-H bond amidations.
S. Lin, B. Lin, Z. Zhang, J. Chen, Y. Luo, Y. Xia, Org. Lett.,
2022, 24, 3302-3306.
Amides react with NaN3 to give acyl azides in DMF at 25°C and
produce symmetrical ureas in THF/H2O at 80 °C via a sequential
acyl substitution and Curtius rearrangement. All acyl azides were also obtained
from secondary amides via sequential reaction with p-toluenesulfonyl
chloride and NaN3. In addition, keto-stabilized iminophosphoranes can
also be prepared in a one-pot reaction.
D. Joseph, S. Lee, Org. Lett.,
2022, 24, 6186-6191.