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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
Author(s) -
Wessels Michael,
Mahajan Vishal,
Boßhammer Stephan,
Raabe Gerhard,
Gais HansJoachim
Publication year - 2011
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201100066
Subject(s) - chemistry , transmetalation , fries rearrangement , lithium (medication) , stereoselectivity , medicinal chemistry , alkylation , selectivity , walden inversion , derivative (finance) , nuclear magnetic resonance spectroscopy , silylation , stereochemistry , catalysis , organic chemistry , medicine , financial economics , economics , endocrinology
Treatment of various phenylsulfoximines with n BuLi (1 equiv.) at –78 °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 °C. The o ‐lithiosulfoximines were efficiently trapped through deuteration, alkylation, silylation, and phosphanylation. Treatment of cyclic phenylsulfoximines also containing H atoms at their α‐positions with n BuLi (1 equiv.) at –78 °C furnished the o ‐lithiosulfoximines with high selectivity, whereas similar treatment at –50 °C to room temperature yielded the corresponding α‐lithiosulfoximines. At elevated temperatures, o ‐lithiosulfoximines also possessing α‐H atoms underwent quantitative o ,α‐transmetalation to afford the corresponding α‐lithiosulfoximines. Treatment of α,α‐disubstituted cyclic and α,α,α‐trisubstituted acyclic phenylsulfoximines with n BuLi (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. Theacyclic 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 o ‐lithiobenzyne, 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.