Rodrigo227

A highly efficient P-stereogenic diphosphine–rhodium complex was applied to the chemo- and enantioselective hydrogenation of allylic hydrazones for the synthesis of chiral allylic hydrazines in 89–96 % yields and with 82–99 % ee values. This methodology was successfully applied to the preparation of versatile chiral allylic amine derivatives.

Diphosphine does the trick: Catalyzed by a P-stereogenic diphosphine–Rh complex, allylic hydrozones were chemo- and enantioselectively hydrogenated to afford chiral allylic hydrazines with high yields and excellent ee values.

Simple benzo-fused nitrogen heterocycles (indolines, tetrahydroquinolines, and their homologues) undergo migratory ring expansion through deprotonation of their benzylic urea derivatives with lithium diisopropylamide (LDA) in the presence of N,N′-dimethylpropylideneurea (DMPU). The products of the reactions are benzodiazepines, benzodiazocines, and their homologues, with ring sizes of 8–12. The reactions tolerate a range of substituent patterns and types, and may exhibit enantiospecificity or diastereoselectivity. Considerable complexity is rapidly generated in an efficient synthesis of these otherwise difficult-to-obtain medium-ring nitrogen heterocycles.

Ringing in ureas: Simple benzo-fused nitrogen heterocycles (indolines, tetrahydroquinolines, and their homologues) undergo migratory ring expansion under basic conditions to generate a range of medium-ring nitrogen heterocycles with ring sizes of 8–12. Considerable complexity is rapidly generated in an efficient synthesis of these otherwise difficult-to-obtain rings.