N-(Alkylsulfamoyl)aldimines: easily deprotected precursors for diarylmethylamine synthesis

The sequential reaction of chlorosulfonyl isocyanate with t-BuOH, t-BuNH2 and TFA allows formation of H2NSO2NHBut. Condensation of the latter with Ar1CHO in the presence of Ti(OEt)4 provides the activated imines Ar1CHNSO2NHBut (59–89%). Commercially available boronic acids add to these imines with good stereoselectivity (76–98% ee) using readily available diene ligands. Simple deprotection with 5% w/w water in pyridine affords free Ar1CHNH2Ar2.

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(S)-N-tert-Butyl-N′-(4-chlorophenyl)(phenyl)methylsulfamideC17H21ClN2O2See = 81%[α]D=-1.9[α]D=-1.9 (c 1.09, CHCl3)Source of chirality: Asymmetric catalysisAbsolute configuration: (1S)

(R)-N-tert-Butyl-N′-(4-fluorophenyl)(phenyl)methylsulfamideC17H21FN2O2See = 95%[α]D=+0.5[α]D=+0.5 (c 0.97, CHCl3)Source of chirality: Asymmetric catalysisAbsolute configuration: (1R)

(R)-N-tert-Butyl-N′-(R)-(4-trifluoromethylphenyl)(phenyl)methylsulfamideC18H21F3N2O2See = 98%[α]D=-3.7[α]D=-3.7 (c 1.35, CHCl3)Source of chirality: Asymmetric catalysisAbsolute configuration: (1R)

(R)-N-tert-Butyl-N′-(4-methylphenyl)(phenyl)methylsulfamideC18H24N2O2See = 95%[α]D=+3.9[α]D=+3.9 (c 0.99, CHCl3)Source of chirality: Asymmetric catalysisAbsolute configuration: (1R)

(S)-N-tert-Butyl-N′-(3-methylphenyl)(phenyl)methylsulfamideC18H24N2O2See = 85%[α]D=-2.0[α]D=-2.0 (c 1.10, CHCl3)Source of chirality: Asymmetric catalysisAbsolute configuration: (1S)

(R)-N-tert-Butyl-N′-(3-methoxyphenyl)(phenyl)methylsulfamideC18H24N2O3See = 97%[α]D=-1.0[α]D=-1.0 (c 1.26, CHCl3)Source of chirality: Asymmetric catalysisAbsolute configuration: (1R)