Catalytic asymmetric Darzens condensation under phase-transfer-catalyzed conditions
作者:Shigeru Arai、Takayuki Shioiri
DOI:10.1016/s0040-4039(98)00081-1
日期:1998.4
The catalytic asymmetric Darzenscondensation promoted by the quaternary ammonium salt (PTC A) derived from cinchonine as a phase-transfer catalyst is described. Treatment of phenacyl chloride with various aldehydes under mild reaction conditions afforded the corresponding desired product in good yield with good to moderate enantiomeric excess.
Photoinduced electron transfer reactions of α,β-epoxy ketones with 2-phenyl-N,N-dimethylbenzimidazoline (PDMBI): Significant water effect on the reaction pathway
Irradiation of aroyl substituted epoxy ketones with 2-phenyl-N,N-dimethylbenzimidazoline in aqueous tetrhhydrofuran or aqueous benzene produced the corresponding aldols in good to excellent yields. Changing the amount of water addedsignificantly influenced the product distribution.
Reductive transformation of α,β-epoxy ketones and other compounds promoted through photoinduced electron transfer processes with 1,3-dimethyl-2-phenylbenzimidazoline (DMPBI)
Photoreactions of epoxy ketones, aromatic ketones, haloketones, and aromatic halides with 1,3-dimethyl-2-phenylbenzimidazoline (DMPBI) were studied Photoinduced single-electron transfer from DMPBI to such substrates initiates the reactions followed by radical radical rearrangement and reduction to finally give several reduced products in modest to good yields. (C) 1999 Elsevier Science Ltd. All rights reserved.
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