- Synthesis of highly substituted cyclohexenes via mixed Lewis acid-catalyzed Diels-Alder reactions of highly substituted dienes and dienophiles
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(Chemical Equation Presented) A high-yielding method is described for the rapid synthesis of very hindered cyclohexenes by the Diels-Alder reaction of hindered silyloxy dienes and dienophiles using the mixed Lewis acid catalyst system (AlBr3/AlMe3). Thus, reaction of the hindered diene 4 with various substituted enones gave good yields of the expected cycloadducts even though both partners are quite sterically hindered.
- Jung, Michael E.,Ho, David,Chu, Hiufung V.
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- Terpenes and Terpenoid Compounds, 17. - Preparation of Oxygenated Tetramethylmethenes and Tetramenthylmenthadienes
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The hydroboration of rac-TM-limonene (1) (TM = tetramethyl) with 9-BBN is chemoselective and allows the functionalization of the isopropenyl side chain to give rac-TM-Δ1-p-Menthen-10-ol (4a,b), the corresponding aldehyde 5a,b, and the acid 6.Protonolysis of the product of hydroboration affords rac-TM-Δ1-p-menthene (7).Hydrochlorination of 1, epoxidation, and treatment with lithium diisopropylamide yields rac-TM-Δ1(7),8-p-menthadien-10-ol (9) which is rearranged by acid into rac-TM-Δ1,8-p-menthadien-10-ol (11).
- Pauluth, Detlef,Hoffmann, H. M. R.
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p. 756 - 764
(2007/10/02)
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