- A facile route to 3-alkoxy-2-methylpropenals, useful intermediates in the synthesis of carotenoids
-
A 'one-pot' process for the preparation of a carotenoid synthon (4) has been developed that involves methoxide-promoted condensation of propionaldehyde with methyl formate, followed by exclusive O-alkylation of the resultant stabilized enolate (6).
- Babler, James H.,Liptak, Vincent P.,Trautmann, Jeffrey A.,Zayia, Gregory H.
-
-
Read Online
- Formation of acetylenic acetals by ring opening of 1,1,2-trihalocyclopropanes under phase-transfer conditions
-
A number of substituted 1,1-dibromo- and 1,1-dichlorocyclopropanes with an additional chlorine or bromine atom attached to C-2 were synthesized in reasonabk to good yields by dihalocarbene addition to the corresponding alkenes under phase-transfer conditions. When the trihalides were treated with 50% aqueous sodium hydroxide in the presence of ethanol. triethylbenzylammonium chloride and dichloromethane. most of the compounds underwent ring opening and afforded mixtures of acetylenic acetals, usually in good yields. The reaction most likely involves cyclopropene intermediates, which in some cases also rearrange to a minor extent to the corresponding vinylcarbenes and afford α,β-unsaturated aldehydes. Acta Chemica Scandinavica 1996.
- Sydnes, Leiv K.,Bakstad, Einar
-
p. 446 - 453
(2007/10/03)
-
- Oxopropenylation of Alkylmagnesium Halides by 3-(Trimethylsilyloxy)acroleins
-
Oxopropenylation of alkylmagnesium halides 4 by 3-(trimethylsilyloxy)acroleins 3 selectively yields the (E)-isomers of α,β-unsaturated aldehydes such as 4-phenyl-2-butenals 9, 3-cyclopropylpropenals 10, 3-cyclohexylpropenals 11, 3-(3-menthyl)propenals 12, and 2,5-hexadienals 13. 3-Hydroxyenolsilylethers 6 are isolated when allylmagnesium chloride is used as carbon nucleophile; to conclude, the reaction primarily involves nucleophilic addition of the Grignard reagent at the aldehyde carbon of the acrolein 3.
- Ullrich, Friedrich-Wilhelm,Rotscheidt, Klaus,Breitmaier, Eberhard
-
p. 1737 - 1744
(2007/10/02)
-
