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Abstract:
This work describes developments of i) a catalytic asymmetric protonation reaction of ketene dithioacetals using a chiral Brønsted acid as a catalyst and ii) a heterogeneous catalysis using textiles as solid support materials. First, for an asymmetric protonation reaction of ketene dithioacetals, we have disclosed a facile preparation of various lactones and hydrocoumarins. The formation and application of ketene dithioacetals was well demonstrated and fully chracterized. The key enantiodetermining step, an asymmetric protonation reaction, was smoothly catalyzed by BINOL‐based Brønsted acids. The desired dithioacetal protected hydrocoumarins were obtained in good yields and high enantioselectivities. The utility of the obtained enantioenriched products were further demonstrated by synthesizing a natural product and conducting a large scale reaction. Secondly, we have successfully demonstrated a facile preparation of textile‐immobilized heterogeneous catalysts. As a general method, photochemical reaction conditions can provide diverse solid‐supported organocatalysts within one‐step from inexpensive starting materials. Further applications and mechanistic studies revealed the high efficiency and application potential of the presented methodology.
