Enantioselective Synthesis of Diverse Sulfinamides and Sulfinylferrocenes from Phenylglycine-Derived Chiral Sulfinyl Transfer Agent

Abstract

A new chiral sulfinyl transfer auxiliary derived from readily available phenylglycine was developed. This auxiliary is utilized to synthesize a diverse array of alkyl- and arylsulfinamides and sulfinylferrocenes in high yields and excellent ee's. The desired products are produced in a one-pot sequence from the oxathiazolidine 2-oxide by two sequential nucleophilic additions that proceed in a stereospecific manner.

Synthesis of Polysubstituted Ferrocenesulfoxides

“…In order to obtain the required 2-substituted ferrocenesulfoxides, ( S )- S - tert -butylferrocenesulfoxide ( S -FcSO t Bu ) was prepared by reacting ferrocenyllithium [ 47 ] with ( S , S )-2,2-diphenyl-1,2-dihydroxypropyl 2- O - tert -butylsulfinate [ 34 ]. ( R )- S - tert -Butylferrocenesulfoxide ( R -FcSO t Bu ) was prepared according to a modified reported procedure [ 48 ]. Finally, racemic S - tert -butylferrocenesulfoxide ( rac -FcSO t Bu ) was obtained by oxidation of ( tert -butylthio)ferrocene [ 49 ] (see Materials and Methods).…”

“…( R )- S - tert -Butylferrocenesulfoxide ( R -FcSO t Bu ) was prepared as reported previously [ 46 ], by modifying a reported procedure [ 48 ].…”

“…For the calculation of the CH acidities, we employed the approach successfully used before in the ferrocene series, including carboxamides [ 47 ], halides [ 48 ], sulfonates [ 71 ], and sulfonamides [ 72 ], and described therein. Briefly, the gas-phase acidity Δ G acid was calculated as the Gibbs energy of deprotonation of the corresponding substrate R-H (R-H(g) → R − (g) + H + (g)): Δ G acid = G 0 298 (R − ) + G 0 298 (H + ) − G 0 298 (R-H) …”

Phosphine–Borane Frustrated Lewis Pairs Derived from a 1,1′-Disubstituted Ferrocene Scaffold: Synthesis and Hydrogenation Catalysis

“…As the starting materials for this study, we employed (dimesitylphosphino)­ferrocene ( 1 ) and 1-(dimesitylphosphino)-1′-vinylferrocene ( 2 ; Note: the synthesis and characterization data of these two compounds are described in the Supporting Information). The former compound was prepared (Scheme ) by lithiation of ferrocene with tert -butyl lithium in the presence of potassium tert -butoxide, and subsequent reaction of the in situ generated lithioferrocene with chloro-dimesitylphosphine. Following chromatographic purification, phosphine 1 was isolated as an orange solid and was characterized by the standard spectroscopic methods and by single-crystal X-ray diffraction analysis (Figure ).…”

Design and Synthesis of Chiral Oxathiozinone Scaffolds: Efficient Synthesis of Hindered Enantiopure Sulfinamides and Sulfinyl Ketimines

“…The success of this method hinged on the recognition that the reactivity of the cyclic oxathiozolidinone 2 could be activated by an electron‐withdrawing substituent on the nitrogen atom ( 3 ), thus allowing for the facile cleavage of the SN bond to provide the desired sulfinate intermediate 4 4a. However the reaction conditions required for the cleavage of the SO bond in 4 to liberate the desired sulfinamides relied heavily on the steric bulk of the R substituent 4c. While the SO bond could be readily cleaved with LHMDS at 0 °C to room temperature to generate some sulfinamides, in the case of hindered substrates [e.g.…”