No abstract

Aporphine compounds constitute a class of substances with important pharmacological properties, including anticancer, antiviral, anti-HIV, anti-inflammatory, and leishmanicidal activities. Consequently, several strategies to obtain the aporphine core have been reported. Herein this review, we provide an overview of two relevant approaches used to construct the Cring in the synthetic routes developed. The first approach, which is based on a one-bond disconnection, allows C-ring formation using a 1-benzyl-1,2,3,4-tetrahydroisoquinoline intermediate (mainly) employing cyclization reactions catalyzed by metals or promoted by light. The second approach, which is derived from a two-bond disconnection, leads to C-ring formation via a sequence of reactions starting with [4 + 2] cycloadditions. Through these approaches, aporphinoids with a diverse range of substitution patterns and biological activities can be synthesized.

Herein, we report our investigations on the reaction of a variety of substituted oxazoles with o-(trimethylsilyl)aryl triflates promoted by potassium fluoride and 18-crown-6-ether. Several functionalized isoquinoline compounds were obtained in moderate to good yields when the transformation was carried out at room temperature, followed by acidic workup, presum-ably via a [4 + 2] cycloaddition-ring-opening reaction pathway. Alternatively, bicyclic ethers were produced in reasonable yields when performing the transformation at 60 °C via a sequence of [4 + 2] cycloaddition, retro-Diels-Alder, and [4 + 2] cycloaddition reactions.