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 formationreactions 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
Functionalized analogues of Tröger's base: scope and limitations of a general synthetic procedure and facile, predictable method for the separation of enantiomers
A major stumbling block in the applications of enantiomerically pure Tröger'sbase analogues is their poor availability. We have therefore developed a facile method for the enantioseparation of functionalized Tröger'sbase analogues possessing various substitution patterns. The systematic separation of a library comprising 36 representatives on the commercially available Whelk O1 chiral stationary
Under typical Vilsmeier–Haack conditions, Troger'sbase undergoes regioselective dimethylamino or arylalkylamino substitution on the methano bridge of the dibenzo[b,f][1,5]diazocine system, revealing a hitherto unknown reactivity pattern. The regioselectivity of the reaction was established by NMR spectroscopy and X-ray crystallography. The key feature of this reaction is its generality; it is compatible
palladium(II)acetate [Pd(OAc)2] under mild conditions. This approach is pivotal on NBS oxidizing the carbon atoms next to the nitrogen atoms in the presence of Pd(OAc)2 followed by a reaction with oxygen‐ or nitrogen‐centred nucleophiles such as KOAc or NaN3 to yield either the mono‐ and bisacetoxylated or azidated Tröger's base derivatives in a stereo‐ and chemoselective manner. The obtained products
Demethylenation of Tröger's Bases with Concomitant Hydrazine Formation
作者:Xuefeng Gao、Carissa S. Hampton、Michael Harmata
DOI:10.1002/ejoc.201201341
日期:2012.12
Trogers bases (TBs) react with dimethyldioxirane to produce the corresponding N-oxides in excellent yields. Upon treatment with acetic anhydride, these N-oxides undergo a Polonovski-type reaction that involves fragmentation and ultimate nitrogen–nitrogen bond formation to form hydrazines. Steric effects are evident in both the oxidation step and in the step involving the activation of the N-oxide, such