ABSTRACT
Terpenoid spiroethers are abundant natural flavors with significant impact, particularly in the food industry. We present in this article the synthesis of new derivatives of the well-known flavors theaspirane and vitispirane using a variant of the Prins cyclization starting from α,ß-unsaturated or heterocyclic ketones. When aromatic ketones were used as the starting materials for Lewis acid-mediated cyclizations, an alternative pathway involving a domino sequence of Prins cyclization, followed by an intramolecular Friedel-Crafts alkylation, gave benzoannelated oxabicyclo[3.3.1]nonane derivatives. Different reaction pathways may be triggered by the reaction temperature to give with good selectivity either tetrahydropyran derivatives as conventional Prins products or oxabicyclo[3.3.1]nonane derivatives.
Subject(s)
Bridged Bicyclo Compounds, Heterocyclic/chemical synthesis , Heterocyclic Compounds/chemical synthesis , Terpenes/chemistry , Bridged Bicyclo Compounds, Heterocyclic/chemistry , Catalysis , Cyclization , Ethers, Cyclic , Heterocyclic Compounds/chemistry , Ketones/chemistry , Molecular Structure , Spiro CompoundsABSTRACT
The bioorthogonal late-stage diversification of functionalized oligopeptides was accomplished through a metal-free, site-selective C-H arylation of engineered indole derivatives under mild reaction conditions.
