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New Adventures in the Synthesis of Hetero‐Bridged syn ‐Facially Fused Norbornadienes (“[ n ]Polynorbornadienes”) and Their Topological Diversity
Author(s) -
Warrener Ronald N.
Publication year - 2000
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200010)2000:20<3363::aid-ejoc3363>3.0.co;2-i
Subject(s) - norbornane , chemistry , methylene bridge , cyclobutene , heteroatom , cycloaddition , methylene , stereochemistry , topology (electrical circuits) , substituent , ring (chemistry) , organic chemistry , mathematics , combinatorics , catalysis
Molecular Scaffolds formed by the linking of bicyclo[2.2.1]heptane (norbornane) subunits by sharing a common C 2 ‐bridge have great appeal to the molecular architect since modelling studies have shown that the syn ‐facially fused members have a curved topology. Furthermore, this curvature can be modified by replacement of the methylene bridge by heteroatom bridges (O, S, NR), and made rod‐like by introducing a σ‐bond between adjoining methylene bridges in sesquinorbornane subunits. This review presents synthetic methodology which allows the stereocontrolled construction of [ n ]polynorbornanes and their hetero‐analogues. Whereas Diels−Alder cycloadditions involving N ‐substituted pyrroles and isoindoles have been used to access the [2] and [3]polynorbornanes, the longer framed [3]−[10]polynorbornanes have been prepared using newly developed 1,3‐dipolar cycloaddition strategies. These reactions depend on the formation of 1,3‐dipolar intermediates by the thermal ring‐opening of substituent‐activated cyclobutene epoxides and aziridines and their trapping with norbornenes and related ring‐strained dipolarophiles.