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Electrophilic additions to tetradehydrodianthracene

✍ Scribed by Herges, Rainer ;Neumann, Helfried

Publisher
John Wiley and Sons
Year
1995
Tongue
English
Weight
712 KB
Volume
1995
Category
Article
ISSN
0947-3440

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✦ Synopsis

Abstract

5,12:6,11‐Di[1,2]benzenodibenzo[a,e]cyclooctene (tetrade‐hydrodianthracene, TDDA) (1) reacts with halogens to give transannular (anti) 4, 5 and ring‐opened (syn) products 6, 7. The product ratio shows a remarkable solvent dependence. Solvents of medium polarity favor anti addition, whereas syn addition is observed both with increasing and decreasing polarity. For instance, chlorine in toluene adds 100% syn, in dichloroethane 56 % anti, and in trifluorethanol again 100% syn. It is concluded that, depending on solvent polarity, three different mechanisms for electrophilic addition are operative.

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Epoxidation of 2, 3,4 with m-CPBA mainly led to the cis-attack products whereas 1 and 6 led to the other selectivity. The result was reversed, from 4, with Payne's reagent. Bromohydroxylation of 4 involved an intermediate bromonium ion syn to the substituents. Haloselenylations occurred with the syn