Brønsted acid-catalyzed synthesis of spirocyclobutanes heteroannulation of vinyloxyphenylbicyclobutanes with water.

We report a perchloric acid-catalyzed heteroannulation for the synthesis of spirocyclobutanes using vinyloxyphenylbicyclobutanes with water. This metal-free reaction yields high product outputs and is consistent with the formation of a cyclobutene intermediate originating from an isomerization of a bicyclobutane.

Development of Cycloisomerization with Rearrangement of a Tosyl Group Using -Tosyl--allenylaniline.

Sulfonyl indoles were synthesized by migratory cycloisomerization from the allene -tosyl--allenylaniline. 3-Tosyl indoles or 4-tosyl indoles were selectively produced using a Pd catalyst or a Au catalyst, respectively.

Heteroannulation of bicyclobutane derivatives Au-catalyzed hydration to enol ethers and intramolecular cyclization giving spirocyclobutanes.

We report the heteroannulations of bicyclobutane derivatives bearing enol ether groups in the presence of HO under mild conditions. The reaction affords spirocyclobutanes with cyclic acetal groups the Au-catalyzed hydration of the enol ether group and subsequent intramolecular cyclization.