corresponding Mannich products by various dimethyl(methylene)ammonium salts under a range of reaction conditions. The several methods used to form these derivatives are compared. Excellent approaches to aldehyde derivatives involve treating the enol silyl ether of the carbonyl compound with methyllithium and then an iminium salt, or directly adding the iminium salt to the enol silyl ether. Ketones may be
Aminoketones were trifluoromethylated by using trialkyl(trifluoromethyl)silanes without any reaction promoters. Formation of cyclic intermediates is proposed to be possible transition states in this reaction. Moderate diastereoselectivities were observed in the trifluoromethylation of the aminoketones having a side chain.
Methylenation of carbonyl compounds using chloromethyl-lithium; a new method for terminal and exocyclic olefins
作者:José Barluenga、José L. Fernández-Simón、José M. Concellón、Miguel Yus
DOI:10.1039/c39860001665
日期:——
The in situ generated chloromethyl-lithium reacts at –78 °C with different aldehydes and ketones to afford, after lithiation with lithium powder, terminal and exocyclic olefins.
The reaction of 4-hydroxycoumarins with 2-dimethylaminoethyl ketones or with dimethylamine + vinyl ketones affords 4-hydroxy-2-oxo-3-(3-oxoalkyl)-2H-1-benzopyrans which undergo carbonyl olefination with methylenetriphenylphosphorane to give 3-(3-butenyl)-4-hydroxy-2-oxo-2H-1-benzopyrans [3-(3-butenyl)-4-hydroxycoumarins].
During the stereospecificsynthesis of diastereoisomeric (+)-1-phenyl-1,2-dimethyl-3-dimethyl-amino-propan-1-ols (III and IV), obtained by reaction of suitable Grignard reagents on α-methyl-β-dimethylamino-propiophenone (I) or on 3-methyl-4-dimethylamino-butan-2-one (II) respectively, the absolute configuration of (−)-amino-alcohol (III) was shown to be 1R, 2S. It was also established that (−)-amino-alcohol