Construction of the Benzindenoazepine Skeleton via Cyclopentannulation of Fischer Aminocarbene Complexes: Total Synthesis of Bulgaramine

Stereoselective [4 + 3] annulation of azadienes and ethyl 4-bromo-3-oxobutanoate: construction of benzindeno-fused azepine derivatives

The benzindenoazepine ring system is an attractive scaffold for biologically active compounds. This work reported a NaH-promoted cycloaddition between azadienes and ethyl 4-bromo-3-oxobutanoate, which delivered a series of benzindenoazepines with good yields and stereoselectivities. Such benzindenoazepine derivatives were not easily obtained by using a traditional approach. The application of this cycloaddition strategy has been extended to azadienes bearing a benzofuran or benzothiophene moiety. The utility of this method was showcased by gram-scale experiments and synthetic transformations of the product.

A room-temperature protocol to access isoquinolines through Ag(i) catalysed annulation of o-(1-alkynyl)arylaldehydes and ketones with NH4OAc: elaboration to berberine and palmatine

A silver catalysed protocol for the synthesis of a wide range of isoquinolines from o-(1-alkynyl)arylaldehydes has been developed under mild conditions and elaborated to the synthesis of berberine and palmatine.

N-Heteropolycyclic compounds from the formal intramolecular (4 + 1)-cycloaddition of chromium aminocarbenes

Chromium aminocarbenes tethered to dienes of all three electronic natures undergo an efficient intramolecular (4 + 1)-cycloaddition to give N-heteropolycyclic compounds. Ligands on chromium had a profound effect on the course of the reaction.

On the Synthesis of Protopine Alkaloids

For the synthesis of protopine alkaloids, we studied a reaction sequence based on a ring enlargement of indeno[2,1-a][3]benzazepines by a singlet oxygen oxygenation, followed by conversion of an amide carbonyl group of the resultant 10-membered keto-lactam to a methylene group, which is the last step for completion of the synthesis. The key substances, indeno[2,1-a][3]benzazepines, were prepared by Bischler-Napieralski cyclization of alkoxy-substituted 1-(2-bromobenzyl)-3-benzazepin-2-ones. Steric effects of the substituents in this synthesis were examined.