Polycyclic indoline‐benzodiazepines can be accessed through the intermolecular reaction of Tröger bases with N‐sulfonyl‐1,2,3‐triazoles. Under RhII catalysis, α‐imino carbenes are generated and a subsequent cascade of [1,2]‐Stevens, Friedel–Crafts, Grob, and aminal formation reactions yield the polycyclic heterocycles as single isomers (d.r.>49:1, four stereocenters including two bridgehead N atoms). Further ring expansion by insertion of a second α‐imino carbene leads to elaborated polycyclic 9‐membered‐ring triazonanes.

In the context of Tröger base chemistry, regio- and stereoselective C -H azidation reactions are reported. Azide functional groups are introduced at either one or the two benzylic positions selectively. Mild conditions and good yields are afforded by the combination of TMSN and iodosobenzene PhIO. The process occurs with high enantiospecificity (es 96-99 %) and-interestingly and importantly-via bridgehead iminium intermediates as shown by mechanistic and in-silico studies. Finally, mono- and bistriazole derivatives were prepared in high yields and enantiospecificity by using copper-catalyzed alkyne azide cycloaddition (CuAAC) reactions; some of the products were used as anion-binding organocatalysts for the tritylation of amines and alcohols.

Polycyclic indoline‐benzodiazepines are afforded in one step by the reaction of Tröger bases with N‐sulfonyl‐1,2,3‐triazoles under Rh(II) catalysis. After α‐imino carbene formation, the process involves a cascade of [1,2]‐Stevens rearrangement, Friedel‐Crafts, Grob fragmentation, and aminal formation reactions. It is highly diastereoselective (d.r. >49:1, four stereocenters incl. two bridgehead N‐atoms). However and in contrast with other reported carbene additions to these moieties, full racemization occurs when enantiopure Tröger bases are used as substrates. To pinpoint the origin of this unexpected behavior, a key elemental step of the mechanism was evaluated and tested. Interestingly, it is not only the initial ring‐opening but also the latter reversible Mannich reaction of the imino‐substituted ethano Tröger base intermediate that is responsible for the loss of enantiospecificity.

Chiral hemicyanine fluorophores are afforded in three steps only from Tröger bases via α-imino carbene additions, an original aminal deprotection and Cu(II)-mediated oxidations. The stable benzodiazepinoindolium salts are readily isolated and present (chir)optical properties that can be fine-tuned by latestage cross-coupling functionalization. The hemicyanine character of dyes was rationalized using first principles.

Polycyclic indoline-benzodiazepines can be accessed through the intermolecular reaction of Trçger bases with N-sulfonyl-1,2,3-triazoles.U nder Rh II catalysis, a-imino carbenes are generated and as ubsequent cascade of [1,2]-Stevens,Friedel-Crafts,Grob,and aminal formation reactions yield the polycyclic heterocycles as single isomers (d.r. > 49:1, four stereocenters including two bridgehead Natoms). Further ring expansion by insertion of asecond a-imino carbene leads to elaborated polycyclic 9-membered-ring triazonanes.