Browsing by Author "Watcharapon Prasitwatcharakorn"

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    Catalytic hydrogen atom transfer from hydrosilanes to vinylarenes for hydrosilylation and polymerization
    (2019-02-01) Parham Asgari; Yuanda Hua; Apparao Bokka; Chanachon Thiamsiri; Watcharapon Prasitwatcharakorn; Ashif Karedath; Xin Chen; Sinjinee Sardar; Kyungsuk Yum; Gyu Leem; Brad S. Pierce; Kwangho Nam; Jiali Gao; Junha Jeon; Umeå Universitet; University of Minnesota Twin Cities; State University of New York College of Environmental Science and Forestry; Mahidol University; Jilin University; University of Texas at Arlington
    © 2019, The Author(s), under exclusive licence to Springer Nature Limited. Because of the importance of hydrogen atom transfer (HAT) in biology and chemistry, there is increased interest in new strategies to perform HAT in a sustainable manner. Here, we describe a sustainable, net redox-neutral HAT process involving hydrosilanes and alkali metal Lewis base catalysts—eliminating the use of transition metal catalysts—and report an associated mechanism concerning Lewis base-catalysed, complexation-induced HAT. The catalytic Lewis base-catalysed, complexation-induced HAT is capable of accessing both branch-specific hydrosilylation and polymerization of vinylarenes in a highly selective fashion, depending on the Lewis base catalyst used. In this process, the Earth-abundant, alkali metal Lewis base catalyst plays a dual role. It first serves as a HAT initiator and subsequently functions as a silyl radical stabilizing group, which is critical to highly selective cross-radical coupling. An electron paramagnetic resonance study identified a potassiated paramagnetic species, and multistate density functional theory revealed a high HAT character, yet multiconfigurational nature in the transition state of the reaction.
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    Efficient synthesis of 2H-chromene derivatives via a dual-organocatalytic reaction
    (2020-10-15) Siriphong Somprasong; Watcharapon Prasitwatcharakorn; Torsak Luanphaisarnnont; Mahidol University
    © 2020 Elsevier Ltd An efficient synthetic method was developed for the selective construction of 2H-chromene derivatives from various salicylaldehydes and acetylenic diesters using a dual catalyst system (p-toluenesulfonic acid monohydrate and pyrrolidine). The advantages of this transformation include high selectivity, good functional group tolerance, operational simplicity, and mild reaction conditions.