- A New Chemoselective Base-Mediated Protection/Deprotection Method for Aldehydes
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A wide range of aldehydes was efficiently protected as pyrrole carbinol derivatives by direct addition of lithium pyrrolate in THF at -78°C. The protection is chemoselective towards aldehydes over ketones and the O-lithiated, O-protonated or O-silylated carbinols may be used to block the aldehyde from nucleophilic and basic reagents at low temperatures. Mild, basic deprotection using DBU, NaOMe or TBAF allows for in situ trapping-reactions (such as Wadsworth-Horner-Emmons olefination) of the released aldehyde.
- Dixon, Darren J.,Scott, Mark S.,Luckhurst, Chris A.
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p. 2317 - 2320
(2007/10/03)
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- Remarkably stable tetrahedral intermediates: Carbinols from nucleophilic additions to N-acylpyrroles
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Sufficiently stable intermediates formed in the reaction of N-acylpyrroles (1) with hydride and Grignard reagents can undergo further synthetic transformations and chromatographic purification to enable the generation of pyrrolecarbinols 2 in 76-95% yields [Eq. (1)].
- Evans, David A.,Borg, George,Scheidt, Karl A.
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p. 3188 - 3191
(2007/10/03)
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- Intramolecular 1,5-hydrogen atom transfer radical reaction of pyrrolidine derivatives
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Intramolecular 1,5-hydrogen atom transfer radical cyclization reaction of pyrrolidine derivatives was examined. Radical reaction of 3,4-bis(α,β- unsaturated acyloxy)-(8, 9) and 3,4-diacetoxy (13)-N-[(o- halobenzyl)pyrrolidines underwent elimination of two acyloxy groups to give mainly N-benzylpyrrole (11). On the other hand, the similar reaction of 3,4- diallyloxy-N-(o-bromobenzyl)pyrrolidine (16) gave desired hexahydrofuro[3,2- b]pyrroles (17, 18) together with a dimeric hexahydrofuro[3,2-b]pyrrole (19).
- Ishizaki, Miyuki,Takano, Hideaki,Hoshino, Osamu
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p. 305 - 314
(2007/10/03)
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- CONVERSION OF PRIMARY AMIDES INTO ACTIVE ACYLATING AGENTS VIA ACYLPYRROLES.
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Several primary amides were converted to N-acylpyrroles on reaction with 1,4-dichloro-1,4-dimethoxybutane (1) and Amberlyst A-21 resin.The acylpyrroles act as active acylating agents.
- Lee, S.D.,Brook, Michael A.,Chan, T.H.
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p. 1569 - 1572
(2007/10/02)
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