- Cycloaromatization of α-oxoketene dithioacetals with 5-lithiomethyl-3-methylisoxazole: A new general method for the synthesis of substituted and annulated 1,2-benzisoxazoles
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A new route to 6-substituted 4a-e and 5,6-annulated 4f-l 1,2-benzisoxazoles have been developed through regioselective 1,2-nucleophilic addition of 5-lithiomethyl-3-methylisoxazole (2) to a variety of α-oxoketene dithiacetals 1a-l and subsequent cycloaromatization of the resulting hydroxyacetals in the presence of boron trifluoride-diethyl ether complex. The corresponding 4-dethiomethylated benzisoxazoles 6a-d were also synthesized by cyclocondensation of β-methylthio-α,β-unsaturated ketones with 2 under identical conditions. The reaction was further extended for the synthesis of (6-benzisoxazolyl)-substituted ethylenes 9a-e, butadienes 9f-g and hexatriene 9h by subjecting α-cinnamoyl ketene dithioacetals 7a-e and their higher enyl analogs 7f-h to similar transformations.
- Pooranchand,Satyanarayana,Ila,Junjappa
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p. 241 - 244
(2007/10/02)
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- CYCLOAROMATIZATION OF α-OXOKETENE DITHIOACETALS WITH 3-METHYL-5-LITHIOMETHYLISOXAZOLE: A NEW GENERAL APPROACH FOR SYNTHESIS OF SUBSTITUTED AND ANNELATED 1,2-BENZISOXAZOLES
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A new general method for the synthesis of substituted and annelated 1,2-benzisoxazoles has been developed by cycloaromatization of α-oxoketene dithioacetals with 3-methyl-5-lithiomethylisoxazole.
- Balu, Maliakel P.,Pooranchand, Dinah,Ila, Hiriyakkanavar,Junjappa, Hiriyakkanavar
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p. 501 - 504
(2007/10/02)
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