Sulfoximine-Directed Single and Double ortho-Lithiation: Stereoselective Rearrangements of o,o′-Dilithiophenylsulfoximines to o,N-Dilithiosulfinylanilines through Anionic Fries Rearrangements of o,o′-Dilithiophenylsulfinamides

Treatment of various phenylsulfoximines with nBuLi (1 equiv.) at -78 degrees C in THF resulted in single ortho-lithiations and gave the corresponding o-lithiosulfoximines. According to NMR spectroscopy, the o-lithiosulfoximines are generally stable at 0 degrees C. The o-lithiosulfoximines were efficiently trapped through deuteration, alkylation, silylation, and phosphanylation. Treatment of cyclic phenylsulfoximines also containing H atoms at their a-positions with nBuLi (1 equiv.) at -78 degrees C furnished the o-lithiosulfoximines with high selectivity, whereas similar treatment at -50 degrees C to room temperature yielded the corresponding a-lithiosulfoximines. At elevated temperatures, o-lithiosulfoximines also possessing alpha-H atoms underwent quantitative o,alpha-transmetalation to afford the corresponding alpha-lithiosulfoximines. Treatment of alpha,alpha-disubstituted cyclic and alpha,alpha,alpha-trisubstituted acyclic phenylsulf-oximines with nBuLi (2 equiv.) at low temperatures led to double ortho-lithiation and furnished the corresponding o,o'-dilithiosulfoximines. At elevated temperatures, cyclic o,o'-dilithiophenylsulfoximines underwent multi-step rearrangements with formation of o,N-dilithiated benzothiazepine and benzothiazocine S-oxide derivatives in high yields. The acyclic o,o'-dilithiophenylsulfoximine underwent a similar rearrangement and gave the corresponding o,N-dilithio-sulfinylaniline derivative. The rearrangements involve 1) elimination of the lithium sulfinamide from the o,o'-dilithiosulfoximine, 2) a Li-N addition of the lithium sulfinamide to the olithiobenzyne, and 3) an anionic Fries rearrangement of the o,o'-dilithiophenylsulfinamide. The rearrangements of the o,o'-dilithiophenylsulfoximines proceeded with overall retention of configuration at sulfur.