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Azabicyclononane durch Fragmentierung, II. Regiospezifische (Grob‐)Fragmentierung zur Darstellung von 3‐Azabicyclononanen
Author(s) -
Risch Nikolaus,
Billerbeck Ulrich,
MeyerRoscher Bernd
Publication year - 1993
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19931260512
Subject(s) - chemistry , ketone , geminal , stereochemistry , halogenation , medicinal chemistry , bicyclic molecule , fragmentation (computing) , nonane , enone , derivative (finance) , organic chemistry , computer science , financial economics , economics , operating system
Azabicyclononanes by Fragmentation, II [1] . – Synthesis of 3‐Azabicyclononanes by Regiospecific (Grob) Fragmentation Clemmensen reduction of the non‐enolizable β1‐dioxo group in the 1‐azaadamantanedione derivative 1 gives the β1‐hydroxy ketone 2 , which is converted to the thioesters 3 . Treatment of 3a or 3b with n Bu 3 SnH/toluene yields the partially deoxygenated monoketone 4 . Chlorination of 2 with SOCl 2 generates 6 (geminal dichlorination). Dehalogenation with n Bu 3 SnH produces 5 . On the other hand, 2 can be monochlorinated to give 7 , selectively. Preparative Grob fragmentation of the aza‐tricyclic skeleton in 7 regiospecifically provides the 3‐azabicyclo[3.3.1]nonane derivative 8 . An even better access to 8 from 2 proceeds via an intermediate tosylate.