Abstract
Abietic acid and its derivatives have broadly been used in fine chemicals and are renewable resources. Its inherent chiral rigid tricyclic phenanthrene skeleton is unique. Its utilities in asymmetric catalysis remain to be explored. A series new amide-type chiral quaternary ammoniums bearing dehydroabietylamine were designed, and prepared by two convenient steps. Acylation of dehydroabietylamine with bromoacetyl chloride afforded amide holding bromoacetyl group in higher yields using triethyl amine as base. Subsequent quaternization reaction gave the desired amide-type chiral quaternary ammoniums. The new chiral quaternary ammoniums can be used as phase-transfer catalyst (PTC) for the transition metal-catalysed alkynylation of isatin derivatives.
Highlights
Agnieszka Siewniak andRosin can be abundantly obtained from pine trees as a kind of unique sustainable and renewable biomass resource
Maruoka reported an interesting work on enantioselective alkynylation of isatin derivatives using a hybrid catalyst system consisting of chiral phase-transfer catalyst (PTC) and transition-metal catalyst [76]
Alkynylation of aldehydes is one of the m preparation of optically active secondary propargylic alco of this transformation, stoichiometric amounts of metal r organomagnesium, and diorganozinc compounds w nucleophilicity of the alkyne
Summary
Agnieszka Siewniak andRosin can be abundantly obtained from pine trees as a kind of unique sustainable and renewable biomass resource. Abietic acid is an essential component of rosin, which has an inherent rigid tricyclic diterpene structure with favorable biocompatibility [1]. Abietic acid and its derivatives are used as raw materials for the preparation of many kinds of fine chemicals due to their rigid hydrophobic structure (Figure 1), such as a monomer of polymer or cross-linking agent [2–14], surfactants [15–21], and bioactive compounds [22–27]. As one of the important commercially available derivatives of abietic acid, dehydroabietylamine has been broadly used in the preparation of antitumor therapies [28–31], epoxy resin [32], and quaternary ammonium surfactants [33–35]. Wang’s group developed a class of a chiral thioureas holding dehydroabietylamine group, which can be used as powerful chiral catalysts for many reactions [38–44], such as Michael addition, aza-Henry reaction, Mannich reaction, and Friedel–Crafts alkylation. A bifunctional squaramide catalyst was designed and utilized for efficient asymmetric Michael/cyclization cascade reaction [45]
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