Preparation of pyrimido[2,1-a]phthalazines and an aminopyrimido[2,1-a]isoindole by retro Diels-Alder reaction

P. Sohár, Ferenc Miklós, A. Csámpai, G. Stájer

Research output: Article

21 Citations (Scopus)

Abstract

The reactions of cis-2-p-toluoylcyclohexanecarboxylic acid 1 with endo,endo- or exo,exo-3-aminobicyclo[2.2.1]heptane- and -hept-5-ene-2-carbohydrazides 2, 4 and 3, 5 yielded partly saturated methylene-bridged phthalazino[1,2-b]quinazolinone diastereomers 6a-6b, 7a-Tb, 8a-8b and 9a-9b, and phthalazino[1,2-b]quinazolinediones 10-13 containing a trans-condensed cyclohexane ring. After separation of the products, the structures were established by means of NMR methods. The diastereomers 6-9 differ in the configurations of the annelational carbons: the hydrogens attached to them lie either on the same side (a) or in pairs on opposite sides (b) of the ring skeleton. On heating, the mixtures of diastereomeric norbornene derivatives 8 and 9 underwent retrodiene decomposition: cyclopentadiene split off to yield the pyrimido[2,1-a]phthalazine 14 containing a cis-fused cycloalkane ring. The reaction of 4 with the aroylbenzoic acid 15 furnished the benzologue 19 directly, while, after isolation from the reaction mixture of 1 and 5, and on heating, 20 resulted in 21 containing a saturated trans-condensed isoindole moiety by cycloreversion.

Original languageEnglish
Pages (from-to)558-564
Number of pages7
JournalJournal of the Chemical Society, Perkin Transactions 1
Issue number5
Publication statusPublished - márc. 7 2001

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Phthalazines
Isoindoles
Quinazolinones
Cycloparaffins
Cyclopentanes
Heating
Heptanes
Acids
Hydrogen
Carbon
Nuclear magnetic resonance
Derivatives
Decomposition

ASJC Scopus subject areas

  • Chemistry(all)

Cite this

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title = "Preparation of pyrimido[2,1-a]phthalazines and an aminopyrimido[2,1-a]isoindole by retro Diels-Alder reaction",
abstract = "The reactions of cis-2-p-toluoylcyclohexanecarboxylic acid 1 with endo,endo- or exo,exo-3-aminobicyclo[2.2.1]heptane- and -hept-5-ene-2-carbohydrazides 2, 4 and 3, 5 yielded partly saturated methylene-bridged phthalazino[1,2-b]quinazolinone diastereomers 6a-6b, 7a-Tb, 8a-8b and 9a-9b, and phthalazino[1,2-b]quinazolinediones 10-13 containing a trans-condensed cyclohexane ring. After separation of the products, the structures were established by means of NMR methods. The diastereomers 6-9 differ in the configurations of the annelational carbons: the hydrogens attached to them lie either on the same side (a) or in pairs on opposite sides (b) of the ring skeleton. On heating, the mixtures of diastereomeric norbornene derivatives 8 and 9 underwent retrodiene decomposition: cyclopentadiene split off to yield the pyrimido[2,1-a]phthalazine 14 containing a cis-fused cycloalkane ring. The reaction of 4 with the aroylbenzoic acid 15 furnished the benzologue 19 directly, while, after isolation from the reaction mixture of 1 and 5, and on heating, 20 resulted in 21 containing a saturated trans-condensed isoindole moiety by cycloreversion.",
author = "P. Soh{\'a}r and Ferenc Mikl{\'o}s and A. Cs{\'a}mpai and G. St{\'a}jer",
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T1 - Preparation of pyrimido[2,1-a]phthalazines and an aminopyrimido[2,1-a]isoindole by retro Diels-Alder reaction

AU - Sohár, P.

AU - Miklós, Ferenc

AU - Csámpai, A.

AU - Stájer, G.

PY - 2001/3/7

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N2 - The reactions of cis-2-p-toluoylcyclohexanecarboxylic acid 1 with endo,endo- or exo,exo-3-aminobicyclo[2.2.1]heptane- and -hept-5-ene-2-carbohydrazides 2, 4 and 3, 5 yielded partly saturated methylene-bridged phthalazino[1,2-b]quinazolinone diastereomers 6a-6b, 7a-Tb, 8a-8b and 9a-9b, and phthalazino[1,2-b]quinazolinediones 10-13 containing a trans-condensed cyclohexane ring. After separation of the products, the structures were established by means of NMR methods. The diastereomers 6-9 differ in the configurations of the annelational carbons: the hydrogens attached to them lie either on the same side (a) or in pairs on opposite sides (b) of the ring skeleton. On heating, the mixtures of diastereomeric norbornene derivatives 8 and 9 underwent retrodiene decomposition: cyclopentadiene split off to yield the pyrimido[2,1-a]phthalazine 14 containing a cis-fused cycloalkane ring. The reaction of 4 with the aroylbenzoic acid 15 furnished the benzologue 19 directly, while, after isolation from the reaction mixture of 1 and 5, and on heating, 20 resulted in 21 containing a saturated trans-condensed isoindole moiety by cycloreversion.

AB - The reactions of cis-2-p-toluoylcyclohexanecarboxylic acid 1 with endo,endo- or exo,exo-3-aminobicyclo[2.2.1]heptane- and -hept-5-ene-2-carbohydrazides 2, 4 and 3, 5 yielded partly saturated methylene-bridged phthalazino[1,2-b]quinazolinone diastereomers 6a-6b, 7a-Tb, 8a-8b and 9a-9b, and phthalazino[1,2-b]quinazolinediones 10-13 containing a trans-condensed cyclohexane ring. After separation of the products, the structures were established by means of NMR methods. The diastereomers 6-9 differ in the configurations of the annelational carbons: the hydrogens attached to them lie either on the same side (a) or in pairs on opposite sides (b) of the ring skeleton. On heating, the mixtures of diastereomeric norbornene derivatives 8 and 9 underwent retrodiene decomposition: cyclopentadiene split off to yield the pyrimido[2,1-a]phthalazine 14 containing a cis-fused cycloalkane ring. The reaction of 4 with the aroylbenzoic acid 15 furnished the benzologue 19 directly, while, after isolation from the reaction mixture of 1 and 5, and on heating, 20 resulted in 21 containing a saturated trans-condensed isoindole moiety by cycloreversion.

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