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Anthracene and Anthrone Eliminations and Rearrangements J. Org. Chem., Vol. 44, No. 21, 1979 3687 1,lO-,1,4-, and 1,2-Eliminations and 1,5-and 1,7-Rearrangementsin the
 

Summary: Anthracene and Anthrone Eliminations and Rearrangements J. Org. Chem., Vol. 44, No. 21, 1979 3687
1,lO-,1,4-, and 1,2-Eliminations and 1,5- and 1,7-Rearrangementsin the
Reactions of Substituted 9-Anisylidene-9,lO-dihydroanthracenesand
Anthrones in Acetic Acid
Zvi RapPoport,* Jeremy Greenblatt, and Yitzhak Apeloigt
Department of Organic Chemistry, The Hebrew University, Jerusalem, Israel
Received March 20, 1979
Solvolysis of 9-(Lu-bromoanisylidene)-9,lO-dihydro-lO-anthracenol(12) in dry AcOH gives first the 10-acetoxy
derivative 13 and 9-anisoylanthracene (16) after a long reaction time. In wet AcOH/NaOAc 1,lO-elimination
of MeOH from 12 or of MeOAc from 13takes place,giving 7-(9-anthryl)-7-bromoquinonemethide (17)probably
by demethylationof the methoxy group of the intermediatea-(9-anthryl)-a-bromo-p-methoxybenzylcation. The
a-H analogue 9 gives a 1,5solvolytic rearrangement to a-anisyl-9-anthrylmethylacetate (19) in AcOH and to
the ethyl ether 21 in EtOH,but anthraceneis also formed by 1,4-elimination.The 10-methylderivative 14 gives
a 1,2-eliminationand solvolysisof the vinyl bromide. Acetolysis of 9-(a-bromoanisylidene)anthrone(11) gives
first the vinyl acetate31 which by a 1,7-acetoxyrearrangementgives 9-acetoxy-10-anisoylanthracene(29). The
mechanismsof these reactions are discussed in terms of a balancebetween the driving forcefor aromatization
of the dihydroanthracenemoiety and steric effects, especially at C,, in the reaction intermediates.
Substituted 5-arylidene-9,10-dihydro-l0-anthracenols
are known to give several elimination and rearrangement
reactions under acidic conditions via the initial formation

  

Source: Apeloig, Yitzhak - Department of Chemistry, Technion, Israel Institute of Technology

 

Collections: Chemistry