3-(Boc-aminomethyl)cyclobutanone

A palladium-catalyzed radical cascade cyanoalkylsulfonylation/cyclization of 3-arylethynyl-[1,1'-biphenyl]-2-carbonitriles with DABCO·(SO2)2 and cyclobutanone oxime esters via cleavage of a C-C single bond and insertion of SO2 was described. A series of cyanoalkylsulfone-containing cyclopenta[gh]phenanthridines were obtained in moderate-to-good yields, thus featuring mild reaction conditions, a broad substrate scope, and a high functional group tolerance.

The radical addition of various α-xanthyl ketones to Boc-protected azetine gives adducts which, when treated with ammonia or primary amines, furnish 2,4-disubstituted, 2,3,4-trisubstituted, and polycyclic pyrroles having a protected aminomethyl group at position 4. An unusual ring-opening was observed in the case of a cyclobutanone precursor.

A novel transformation for the construction of Csp3-Csp bonds was achieved via a photo-induced copper-catalysed C-C bond cleavage. This approach was applied to prepare a series of highly functionalized alkynyl nitriles using readily available cyclobutanones and terminal alkynes. Mechanistic exploration showed that the in situ generated copper acetylide complex is an effective photosensitive catalyst to promote the C-C bond cleavage of cycloketoxime esters through a radical process.