The importance of axial chirality in enantioselective synthesis has been widely recognized for decades. The practical access to certain structures such as biaryl amino phenols known as NOBINs in enantiopure form, however, still remains a challenge. In drug delivery, the incorporation of axially chiral molecules in systematic screening has also received a great deal of interest in recent years, which calls for innovation and practical synthesis of structurally different axially chiral entities. Herein we present an operationally simple catalytic
N
-alkylation of sulfonamides using commercially available chiral amine catalysts to deliver two important classes of axially chiral compounds: structurally diverse NOBIN analogs as well as axially chiral
N
-aryl sulfonamides in excellent enantiopurity. Structurally related chiral sulfonamide has shown great potential in drug molecules but enantioselective synthesis of them has never been accomplished before. The practical catalytic procedures of our methods also bode well for their wide application in enantioselective synthesis.
We report herein
an atroposelective N-acylation of sulfonamides
using a commercially available isothiourea catalyst, (S)-HBTM, with a simple procedure. The N-sulfonyl
anilide products can be obtained in good to high enantiopurity, which
represents a new axially chiral scaffold. The application of the product
as a chiral iodine catalyst is also demonstrated for the asymmetric
α-oxytosylation of propiophenone.
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