Synthesis of Allenyl Sulfones via a TBHP/TBAI-Mediated Reaction of Propargyl Alcohols with Sulfonyl Hydrazides

A new
TBHP/TBAI-mediated reaction of propargyl alcohols with sulfonyl
hydrazides in the presence of HOAc has been established, in which
a wide variety of allenyl sulfones were obtained in moderate to excellent
yields. Mechanistic studies indicate that this transformation involves
HOAc-promoted sulfonohydrazide intermediate formation, sequential
C–O, C–N, and N–S bond cleavage, and C–S
bond formation. Significantly, this sulfonohylation proceeds in a
radical process and shows highly functional group compatibility and
excellent regioselectivity, with a short reaction time and inexpensive
reagents.