Base-Promoted Reactions of .alpha.-Azido Ketones with Aldehydes and Ketones: A Novel Entry to .alpha.-Azido-.beta.-hydroxy Ketones and 2,5-Dihydro-5-hydroxyoxazoles
摘要:
The base-promoted reaction of alpha-azido ketones with aldehydes and ketones provides a new and simple route to either alpha-azido-beta-hydroxy ketones, which are valuable 1,2,3-trifunctionalized synthons, or 2,5-dihydro-5-hydroxyoxazoles, which are a little known type of oxazoline. These two products are formed by the electrophilic trapping of two different anions that are produced sequentially during the reaction, The alpha-azido-beta-hydroxy ketones are formed by an aldol reaction between an enolate of the alpha-azidoketone and an aldehyde. The 2,5-dihydro-5-hydroxyoxazoles are formed by electrophilic trapping of an imino anion which is produced by nitrogen loss from the cx-azido ketone enolate.
One-pot preparation of 2,5-disubstituted and 2,4,5-trisubstituted oxazoles from aromatic ketones with molecular iodine, oxone, and trifluoromethanesulfonic acid in nitriles
Alkyl aryl ketones were successfully converted into the corresponding 2,5-disubstituted and 2,4,5-trisubstituted oxazoles in good to moderate yields in a one-pot manner, utilizing iodine, Oxone®, and trifluoromethanesulfonic acid in nitriles under transition-metal-free conditions. The present method could be used for the preparation of Oxaprozin from benzyl phenyl ketone and succinonitrile. A possible
Iodoarene-Mediated One-Pot Preparation of 2,4,5-Trisubstituted Oxazoles from Ketones
作者:Hideo Togo、Yuhta Kawano
DOI:10.1055/s-2007-1000871
日期:2008.1
2-Methyl-5-aryloxazole and 2-ethyl-5-aryloxazole derivatives were smoothly and efficiently obtained in one-pot manner fromalkyl aryl ketones with iodoarene, m-chloroperbenzoic acid, and trifluoromethanesulfonic acid in acetonitrile and propionitrile, respectively. In these reactions, iodoarene works as a catalyst.
Iodoarene-catalyzed one-pot preparation of 2,4,5-trisubstituted oxazoles from alkyl aryl ketones with mCPBA in nitriles
作者:Yuhta Kawano、Hideo Togo
DOI:10.1016/j.tet.2009.05.003
日期:2009.8
aryliodonium I(III) species reacts with alkylaryl ketone to form β-keto aryliodonium species. This in turn, reacts with nitrile to form the corresponding oxazole. Iodoarene works as a catalyst. However, one equivalent of iodoarene is required because one equivalent of reactive aryliodonium I(III) species must be formed prior to the reaction with alkylaryl ketone. Then, by introducing an ionic liquid
Iodoarene-mediated one-pot preparation of 2,5-disubstituted and 2,4,5-trisubstituted oxazoles from alkyl aryl ketones with oxone in nitriles
作者:Yoshihide Ishiwata、Hideo Togo
DOI:10.1016/j.tet.2009.09.109
日期:2009.12
aryliodonium I(III) species reacts with alkylaryl ketone to generate β-keto iodonium species. Then, β-keto iodonium species reacts with nitrile to produce the corresponding oxazole. In principle, iodoarene works as a catalyst. However, 1 equiv of iodoarene is required because 1 equiv of reactive aryliodonium I(III) species must be formed before the reaction with alkylaryl ketone.
Coordination‐Controlled Nickel‐Catalyzed Benzylic Allylation of Unactivated Electron‐Deficient Heterocycles
作者:Pengpeng Zhang、Jin Wang、Zoe R. Robertson、Timothy R. Newhouse
DOI:10.1002/anie.202200602
日期:2022.5.23
A nickel-catalyzed benzylic allylation and benzylation of 14 types of unactivated heterocyclic aromatic compounds is described. The selective deprotonation of benzylic sites is hypothesized to be controlled by the original coordination of a heterocyclic nitrogen to Zn(TMP)2. In addition to the pro-nucleophiles, readily available bromide and chloride electrophiles could be used.