Steric Hindrance-Driven Access to 3,4,7-Trihydro-1,2-oxaphosphepine 2‑Oxides from Vinyloxiranes and Phosphoryl Diazomethanes

Various
3,4,7-trihydro-1,2-oxaphosphepine 2-oxides are synthesized
in satisfactory to excellent yields from 2-aryl-2-vinyloxiranes and
in situ-generated phosphenes from phosphoryl diazomethanes via the
phosphene-induced and steric hindrance-driven ring expansion of vinyloxiranes.
The reaction is an unprecedented synthetic strategy for 1,2-oxaphosphepine
2-oxide derivatives, featuring ring expansion of readily available
starting materials, a fast reaction rate, high atom economy, no catalyst,
and separable diastereomers.