Flash vacuum pyrolysis of
5,5-ethylenedioxy-7a-methyl-4,5,6,7-tetrahydro-2H-inden-1(7aH)-one (2) at 630�
gave a good yield of 2-ethenyl-4,4-ethylenedioxy-1-methylcyclohex-1-ene (6),
but at 740� p-cresol was the major product. The diene acetal (6) was also obtained
by pyrolysis of 5,5-ethylene- dioxy-lβ-hydroxy-7a-methyl-1,2,5,6,7,7a-hexahydro-4H-indene-1α-carbonitrile (3) at 600�. Pyrolytic reactions of
7a-methyl-2,3,7,7a-tetrahydro-1H-indene-1,5(6H)-dione (1),
5,5-ethylenedithio-7a- methyl-2,3,5,6,7,7a-hexahydro-1H-inden-1-one (7) and of
1,1-ethylenedioxy-3,5,5-trimethylcyclohex- 3-ene (8) are also described. Mild
hydrolysis of the diene acetal (6) afforded
3-ethenyl-4-methylcyclohex-3-en-1-one (9) which upon brief treatment with dry
hydrogen chloride in chloroform at 0� gave, after preparative thin-layer
chromatography, a low yield of pure 3-ethenyl-4-methylcyclohex-2-en-1-one (11).
The diene acetal (6) failed to undergo Diels-Alder reactions, even at high
pressures with Lewis acid catalysts, and it reacted anomalously with two
molecules of 4-phenyl-1,2,4-triazoline-3,5-dione; the isomeric diene acetal
1-ethenyl-3,3-ethylenedioxy-6-methylcyclohex-1-ene (18) gave the expected
Diels-Alder adduct with this reagent.
闪速真空热解
5,5-亚乙二氧基-7a-甲基-4,5,6,7-四氢-2H-茚-1(7aH)-酮(2)在 630℃下进行闪速真空热解。
的条件下,可以很好地生成 2-乙烯基-4,4-亚乙二氧基-1-甲基环己-1-烯(6)、
但在 740℃时,对甲酚是主要产物。对甲酚是主要产物。
5,5-乙烯-二氧-lβ-羟基-7a-甲基-1,2,5,6,7,7a-六氢-4H-茚-1α-甲腈(3)在 600� 的温度下进行热解,也可以得到二烯缩醛(6)。的热解反应。
7a-methyl-2,3,7,7a-tetrahydro-1H-indene-1,5(6H)-dione (1),
5,5-亚乙二氧基-7a-甲基-2,3,5,6,7,7a-六氢-1H-茚-1-酮(7)和
1,1-ethylenedioxy-3,5,5-trimethylcyclohex- 3-ene (8)。轻度
二烯缩醛 (6) 的温和水解可得到
3-乙烯基-4-甲基环己-3-烯-1-酮(9)。
氯仿中的干氯化氢在 0� ℃下进行短暂处理后,经过制备薄层
经制备薄层色谱法处理后,可得到低产率的纯 3-乙烯基-4-甲基环己-2-烯-1-酮 (11)。
即使在路易斯酸催化剂的高压作用下,二烯缩醛(6)也无法发生 Diels-Alder 反应。
在路易斯酸催化剂的作用下,二烯缩醛(6)也不能发生 Diels-Alder 反应。
它与两分子 4-苯基-1,2,4-三唑啉-3,5-二酮发生了异常反应;异构二烯缩醛
1-ethenyl-3,3-ethylenedioxy-6-methylcyclohex-1-ene (18)产生了预期的
Diels-Alder 加合物。