From Other Carbocyclic Derivatives as Substrates

Both carbomonocyclic (other than benzene derivatives, already discussed) and carbobicyclic substrates have been used sparingly (with or without ancillary synthons) for the primary synthesis of phthalazines. The examples that follow are grouped under the parent name of the system used as substrate. 

5-Tetrachlorobicyclo[4.2.0]octa-l(6),2,4-triene-7,8-dione (124) with hydrazine hydrochloride gave 5,6,7,8-tetrachloro-l(2H)-phthalazinone (125, R = H) (EtOH, reflux, 24 h 71%) or with phenylhydrazine gave 5,6,7,8-tetra-chloro-2-phenyl-l(2H)-phthaIazinone (125, R = Ph) (H2SO4, EtOH, reflux, 2 h 79%) the same substrate (124) was converted into its monophenylhy-drazone (126) (PhNHNHa, H2SO4, EtOH, reflux, briefly 46%) and thence 

Bicyclo[4.2.0]octa-l(6),2,4-triene-7,8-dione (127) with azobenzene gave 2,3-diphenyl-l,4(2ff,3/f)-phthalazinedione (128) (CH2CI2, CfiHia, hv, 9 h 72%).  

2-Diphenyl-1,3-indanedione (129) gave 4-diphenylmethyl-l(2//)-phthalazi-none (130) (neat H2NNH2 H2O, reflux, 15 min 92%) several analogs like- 

4-(3-Hydroxy-l-oxo-l//-inden-2-yl)pyridine (131) gave 4-(pyridin-4-ylmethyl)-l(2F/)-phthalazinone (132) (neat H2NNH2.H2O, 110°C, 8h 82%) analogs likewise.  

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From Other Carbocyclic Derivatives as Substrates Indenes as Substrates... 

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