Rigid fused-ring compounds

Rigid fused-ring compounds such as 18 and 19 have been investigated and it was shown that for this pair the protons Hjos and Hioa absorb at 5.00 and 3.75 ppm respectively. For 20 and 21 the corresponding data are 4.80 and 3.60 ppm and for 22 and 23,4.42 and 3.93 ppm. The significant values of AS in these pairs of epimers were attributed... 

Incorporation of other heteroatoms to phosphole-containing heteroarenes also leads to interesting molecular properties. One common example is the incorporation of thiophene units (Figure 12.10). These phospholes have high photoluminescence quantum yields due to their limited degrees of freedom from the rigid, fused ring system. Like many of the compounds discussed herein, these... 

This class of rigid tricyclic fused oxazolidinones was synthesized in order to gain an understanding of the importance of the spatial relationship and torsional angle between the aryl and oxazolidinone rings with regard to antibacterial activity [51,65]. Considering the structure of an early lead compound,... 

I) a chiral compound, containing heteroatoms, which interacts with organometallic compound(s) generating structurally rigid chelate complexes as intermediates, caul (II) such intermediates should necessarily be of conformationally restricted cis-fused 5-membered ring structure. 

Centropolyindanes constitute a complete family of arylaliphatic polycyclic hydrocarbons containing several indane units. Mutual fusion of the five-membered rings leads to three-dimensional, carbon-rich molecular frameworks bearing a central carbon atom, such as benzo-annelated [3.3.3]propellanes, triquinacenes, and [5.5.5.6]- and [5.5.5.5]fenestranes. In this review, the structural concept of centropolyindanes is contrasted to other fused indane hydrocarbons. Besides the syntheses of the parent centropolyindanes and recently described related indane hydrocarbons, the preparation of a large variety of bridgehead and arene substituted centropolyindanes is presented including strained, heterocyclic, and centrohexacyclic derivatives. In appropriate cases, the particular reactivity and some structural features of these unusual, sterically rigid polycyclic compounds are pointed out. 

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