Syntheses and Biological Properties of Pyrido[3,4‐ b ]homotropane (PHT) and its Analogues with Bridged Aza‐[ n .2.1] Skeletons

Concise syntheses of (-)-quinocarcinol methyl ester and (-)-oxa-quinocarcinol methyl ester

A concise synthesis of (-)-quinocarcinol methyl ester was accomplished with an overall yield of 39% through a 9-step longest linear sequence (LLS). Our synthesis features a two-step ester reduction/reductive amination sequence, a stereoselective [3 + 2] intramolecular cross-cycloaddition for the construction of bicyclo[3.2.1]octane skeletons, four simultaneous hydrogenolysis reactions in a one-pot process, and a stereoselective Krapcho decarboxylation. By following this protocol, (-)-oxa-quinocarcinol methyl ester was also achieved.

Formal Syntheses of (-)-Quinocarcinamide and (-)-Quinocarcin

Concise and scalable formal syntheses of (-)-quinocarcinamide and (-)-quinocarcin have been achieved in 9 steps with 9% overall yield from simple commercially available chemicals. The synthetic strategy features an ortho-regioselective Pictet-Spengler cyclization for the construction of the tetrahydroisoquinoline skeleton, a stereoselective formal intramolecular [3 + 2] cross cycloaddition of cyclopropane 1,1-diester with an imine for the construction of the 3,8-diazabicyclo[3.2.1]octane skeleton.

Recent progress in the synthesis of homotropane alkaloids adaline, euphococcinine and N-methyleuphococcinine

The 9-azabicyclo[3.3.1]nonane ring system is present in several insect- and plant-derived alkaloids. (-)-Adaline (1) and (+)-euphococcinine (2), found in secretions of Coccinelid beetles, and (+)-N-methyleuphococcinine (3), isolated from the Colorado blue spruce Picea pungens, are members of this alkaloid family. Their unique bicyclic system with a quaternary stereocenter, and the potent biological activity exerted by these homotropane alkaloids, make them attractive synthetic targets. This work aims briefly to review the chemical ecology of Adalia bipunctata and the recent methodologies to obtain adaline (1), euphococcinine (2), and N-methyleuphococcinine (3).