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The alkyne aza-Prins cyclization of 3,5-diynyl amides and various aldehydes was developed using TfOH with/without (Me2AlO)2SO2. This method, which could be applied to homopropargyl amides, provides TfO-substituted pyrrolidines with E-selectivities and exclusive regioselectivities. This work represents a first example of the aza-Prins cyclization with the introduction of TfO groups. [ABSTRACT FROM AUTHOR]

A BINOL-derived chiral bifunctional sulfide catalyst bearing a phenylurea moiety was applied to enantioselective bromoaminocyclization reactions of 2-allylaniline derivatives, which provide optically active 2-substituted indoline products as important motifs for biologically active compounds. A protecting group on the nitrogen of the 2-allylaniline substrate was carefully optimized, and highly enantioselective reactions were achieved by employing the p-biphenylsulfonyl-protected substrates. The origin of the good level of enantioselectivity for the present bromoaminocyclization was also investigated on the basis of DFT calculations. The resultant optically active 2-(bromomethyl)indoline products could be transformed to various 2-substituted indolines with no loss of the optical purity.

An efficient enantioselective synthesis of 3,3-disubstituted phthalides possessing a chiral quaternary carbon center was achieved via catalytic asymmetric bromolactonization that utilized BINOL-derived bifunctional sulfide catalysts. Transformations of the bromo group in optically active phthalide products were also performed to demonstrate the utility of this novel synthetic protocol.