Stereoselective organocatalytic oxidation of alcohols to enals: A homologation method to prepare polyenes
A novel method for organocatalytic oxidation through oxidative enamine catalysis was developed with excellent compatibility for the direct syntheses of enals from simple saturated alcohols. By using this amine-catalyzed IBX-oxidation, a wide range of aromatic and aliphatic substituted enals were successfully generated in high yields and exclusively stereoselective E-geometry. Moreover, varying the solvents and/or the loading amounts of IBX allowed for the selective oxidation of alcohols and aldehydes. Importantly, the homologous application of this method provided a selective and efficient way of preparing various highly sensitive conjugated polyene frameworks, which are enriched in natural products.
Thiourea/proline derivative-catalyzed synthesis of tetrahydrofuran derivatives: A mechanistic view
A thiourea/proline derivative-catalyzed synthesis of linear α-substituted tetrahydrofuran/pyran derivatives starting with lactol substrates is presented. This study demonstrates the utility and potential complications of using (thio)urea/proline cocatalysis as each of these catalysts is necessary to provide the observed reactivity, but a time-dependent decrease in enantioselectivity is observed. New mechanistic insights into (thio)urea/proline cocatalysis are presented.
Opalka, Suzanne M.,Steinbacher, Jeremy L.,Lambiris, Brandon A.,McQuade, D. Tyler
experimental part
p. 6503 - 6517
(2011/10/02)
Inter- and intramolecular [4 + 1]-cycloadditions between electron-poor dienes and electron-rich carbenes
Inter- and intramolecular [4 + 1]-annulations between dialkoxy carbenes and electron-deficient dienes afford mono- or bicyclic products in moderate to good yield. Copyright
Spino, Claude,Rezaei, Hadi,Dupont-Gaudet, Kristina,Belanger, Francis
p. 9926 - 9927
(2007/10/03)
Activation of the reverse-cope elimination by allylic oxygen functions: Syntheses of (-)-hygroline and (+)-pseudohygroline
Reverse-Cope cyclisations of N-(4-alkenyl)hydroxylamines 8 are accelerated by the presence of the allylic oxygen function; this has been applied to a brief synthesis of the alkaloids (-)-hygroline 6 and (+)- pseudohygroline 7.
Knight, David W.,Salter, Rhys
p. 5915 - 5918
(2007/10/03)
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