The secondary metabolite, turkiyenine, is a probable bioactive component of the medicinal plant, Hypecoum procumbens L. Structurally, it is an isoquinoline-derived alkaloid composed of dihydrobenzofuran and 3-benzazepine-1-one moieties arranged in a unique spirocyclic structure. Yet despite the intriguing structure and medicinal relevance of benzofuran and benzazepine motifs, neither a synthetic study nor a biological evaluation of turkiyenine have been reported to date. Herein we communicate the first total synthesis of the proposed structure of turkiyenine, and on the basis of X-ray crystallography show that the proposed structure is incorrect. The key steps of our synthesis include an aza-spiro annulation onto a benzofuran using a rhodium–nitrenoid to construct a 3-alkyl-3-amino-2,3-dihydrobenzofuran, an acyl-alkylation of an aryne onto a β-ketolactam to form a 3-benzazepine-1-one, and chemoselective reduction of an amide in the presence of a ketone.

The oxidation of alcohols into their corresponding carbonyl compounds is one of the most fundamental transformations in organic chemistry. In our recent report, 2-azaadamantane N-oxyl (AZADO)/copper catalysis promoted the highly chemoselective aerobic oxidation of unprotected amino alcohols into amino carbonyl compounds. Herein, we investigated the extension of the promising AZADO/copper-catalyzed aerobic oxidation of alcohols to other types of alcohol. During close optimization of the reaction conditions by using various alcohols, we found that the optimum combination of nitroxyl radical, copper salt, and solution concentration was dependent on the type of substrate. Various alcohols, including highly hindered and heteroatom-rich ones, were efficiently oxidized into their corresponding carbonyl compounds under mild conditions with lower amounts of the catalysts.

The direct oxidation of unprotected amino alcohols to their corresponding amino carbonyl compounds has often posed serious challenges in organic synthesis and has constrained chemists to adopting an indirect route, such as a protection/deprotection strategy, to attain their goal. Described herein is a highly chemoselective aerobic oxidation of unprotected amino alcohols to their amino carbonyl compounds in which 2-azaadamantane N-oxyl (AZADO)/copper catalysis is used. The catalytic system developed leads to the alcohol-selective oxidation of various unprotected amino alcohols, carrying a primary, secondary, or tertiary amino group, in good to high yield at ambient temperature with exposure to air, thus offering flexibility in the synthesis of nitrogen-containing compounds.

The direct oxidation of unprotected amino alcohols to their corresponding amino carbonyl compounds has often posed serious challenges in organic synthesis and has constrained chemists to adopting an indirect route, such as a protection/deprotection strategy, to attain their goal. Described herein is a highly chemoselective aerobic oxidation of unprotected amino alcohols to their amino carbonyl compounds in which 2-azaadamantane N-oxyl (AZADO)/copper catalysis is used. The catalytic system developed leads to the alcohol-selective oxidation of various unprotected amino alcohols, carrying a primary, secondary, or tertiary amino group, in good to high yield at ambient temperature with exposure to air, thus offering flexibility in the synthesis of nitrogen-containing compounds.