Rhodium(II)-Catalyzed Alkyne Amination of Homopropargylic Sulfamate Esters: Stereoselective Synthesis of Functionalized Norcaradienes by Arene Cyclopropanation

A rhodium­(II) catalyzed nitrene–alkyne
cycloaddition of
stereochemically well-defined homopropargylic ethers is followed by
arene cyclopropanation to afford unique tetracyclic norcaradiene products
bearing a cyclic sulfamate. Products from the arene cyclopropanation
(Buchner reaction) can be converted to fused cycloheptatrienes via
a ring enlarging electrocyclization after nucleophilic ring opening
of the cyclic sulfamate ester.