The Reaction of Methanol with 3-Methylphthalic Anhydride

Rabjohn, Norman; Farmer, H. H.

doi:10.1021/ja01608a068

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“…The work of Bird and Turner on the selective esterification of 3-chlorophthalic acid (21) encouraged our similar approach with 3-methylphthalic acid. Treatment of the diacid with methanol and sulphuric acid gave the desired half ester 28 in 6 5 z yield along with 2 6 x of the diester 29 (22 (24,25). This also completed another synthesis of the main target structure.…”

Section: John E Francis Karl J Doebel Paula M Schutte Edgar C mentioning

confidence: 74%

“…The intermediates 19,20,21,25, and 31 were all converted in one or two stages to 3-oxo-3H-2,9(or 1,2)- hydrazine hydrate gave 3,4-dihydro-4-0x0-5-phthalazinecarboxylic acid (420) which was further reacted with 85% hydrazine hydrate over 34 days to produce 41 in 65% yield. The intermediate 27 was converted in ethanolic hydrazine hydrate to the ester 42b which was used for other purposes, but the methyl ester 42c was prepared from the acid 42cr either by treatment with diazomethane or by reaction with thionyl chloride followed by methanol, and this ester was converted to 41 in refluxing ethanolic hydrazine hydrate.…”

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confidence: 99%

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Pyridazino[3,4,5-de]phthalazines. I. Synthesis of the heterocyclic system and key intermediates

Francis¹,

Doebel²,

Schutte³

et al. 1979

Can. J. Chem.

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. Can. J. Chem. 57. 3320 (1979). 1H-Pyridazino[3,4,5-delphthalazine (4) and 3-hydrazino-l(or 9)H-pyridazino[3,4,5-de]-phthalazinc (6) represent intramolecular hydrazones of the drugs hydralazine and dihydralazine. respectively. These novel heterocycles were synthesized by several different routes starting from 2,6-dimethylbenzoic acid, 3-methylphthalic anhydride, or hemimellitic acid. Tetrabromination of 2,6-dimethylbenzoic acid with bromine and carbon tetrachloride under free radical conditions followed by treatment with dilute aqueous hydrazine hydrate produced pure 4 in yields up to 58%. Treatment of 3-methylphthalic anhydride with 2 mol of N-bromosuccinimide under radical conditions followed by reaction of the dibromo con~pound with hydrazine hydrate in methyl Cellosolve produced 3-0x0-3H-2,9(or 1,2)-dihydropyridazino[3,4,5-delphthalazne in 60% yield. This intermediate was converted to the 3-thiono compound or 3-chloro-l(or 9)Hpyridazino[3,4,5-delphthalazine from which the hydrazine 6 was generated by hydrazine hydrate treatment. This hydrazine was further characterized by conversion with acid chlorides to novel tctracyclic condensed triazolcs or by nitrous acid to a tctracyclic condenscd tctrazole. The unsubstituted heterocycle 4 was uninteresting in pharmacological screens but the hydrazine 6 resembled hydralazine by lowering blood pressure in several animal test models and in limited clinical trials.

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Section: John E Francis Karl J Doebel Paula M Schutte Edgar C mentioning

confidence: 74%

mentioning

confidence: 99%