INTRAMOLECULAR AND INTERMOLECULAR DIELS-ALDER REACTIONS OF ACYLHYDRAZONES DERIVED FROM METHACROLEIN AND ETHYLACROLEIN

被引:18
作者
ALLCOCK, SJ
GILCHRIST, TL
SHUTTLEWORTH, SJ
KING, FD
机构
[1] UNIV LIVERPOOL,DEPT CHEM,POB 147,LIVERPOOL L69 3BX,ENGLAND
[2] SMITHKLINE BEECHAM PHARMACEUT,MED RES CTR,HARLOW CM19 5AD,ESSEX,ENGLAND
关键词
D O I
10.1016/S0040-4020(01)96054-5
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
The intramolecular Diels-Alder reactions of hydrazones derived from methacrolein or ethylacorlein and terminally unsaturated N-acyl-N-methylhydrazines have been investigated. The hydrazones 7b and 7c derived from N-methyl-N-pent-4-enoylhydrazine 3b were found to undergo intramolecular [4 + 2] cycloaddition above 140-degrees-C and the pyridopyridazines 12 were isolated. The corresponding hydrazones 8b and 8c from N-methyl N-pent-4-ynoylhydrazone 4a reacted similarly and gave as the final products the pyridines 13. The scope of the reaction is limited, as was shown by the failure of several other terminally unsaturated hydrazones of alpha-beta-unsaturated aldehydes to undergo intramolecular cycloaddition. These hydrazones did, however, undergo intermolecular [4 + 2] cycloaddition to N-phenylmaleimide. Other hydrazones 15 of methacrolein, including the benzoylhydrazone and the phenylhydrazone, also reacted with N-phenylmaleimide to give the pyridine 14b by way of an isolable dihydropyridine 16.
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页码:10053 / 10064
页数:12
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