An efficient route to N-alkylated 3,4-dihydroisoquinolinones with substituents at the 3-position.

A facile synthetic procedure for the production of N-alkylated 3,4-dihydroisoquinolinone derivatives is described. The desired products were obtained by N-alkylation of 3,3'-dimethyl-3,4-dihydroisoquinoline derivatives followed by oxidation of the resulting iminium salts. Reaction conditions for both steps were very mild and the desired cyclization products could be obtained in good yield. This strategy allows the generation of N-substituted 3,4-dihydroisoquinolinone derivatives with substituents at the 3-position.

Total Synthesis of (±)-Englerin†A Using An Intermolecular [3+2] Cycloaddition Reaction of Platinum-Containing Carbonyl Ylide.

Total synthesis of (±)-Englerin A has been achieved starting from γ,δ-ynone 5 in 14 steps. The key feature of this synthesis is the highly efficient and stereoselective preparation of 8-oxabicyclo[3.2.1]octane derivative 6, a core skeleton of Englerin A, based on an inverse electron-demand [3+2] cycloaddition reaction of the platinum-containing carbonyl ylide, which was developed in our laboratory.