1 -Bromo-9- triptycene

C20H13] Reaction of Si(CH2CH3)3 with corresp. 9-bromo-triptycene derivative Cyclopropane ESR/160 2.003(1) 95Binl... 

These results suggested examination of the buttressing effect in bromo compounds, so 1,2,3,4-tetrabromo- and l-bromo-9-(l,l-dimethyl-2-phenylethyl)-triptycenes were prepared. As expected, the tetrabromo compound had a relatively low barrier of 35.1 kcal/mol at 500 K. In contrast, the free energy of activation for rotation of the monobromo compound was 39.2 kcal/mol. The difference amounts to 4.1 kcal/mol (151). The reverse buttressing effect can be large if the substituents concerned are large. 

Conversion of this diamine to triptycene has, however, been accomplished in 40-45% yield by diazotizing with sulfuric acid l-bromo-2,5-diaminotriptycene (XXI) has also been deaminated by this procedure.83... 

The successful deamination of l-nitro-2-aminonaphthalene, 2,5-diamino-triptycene (XX), and l-bromo-2,5-diaminotriptycene (XXI) suggests that 5-amino-8-nitroisoquinoline (XVIII) also could be deaminated to 8-nitroisoquinoline if the diazotization were carried out in sulfuric acid. 

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