Rhodium-catalyzed heterocycloaddition route to 1,3-oxazoles as building blocks in natural products synthesis
作者:Richard D. Connell、Mark Tebbe、Anthony R. Gangloff、Paul Helquist、Björn Åkermark
DOI:10.1016/s0040-4020(01)87261-6
日期:——
Rhodium(II) acetate serves as a catalyst for the heterocycloaddition reaction of diazodicarbonyl compounds with nitriles to give functionalized 1,3-oxazole derivatives in a simple one-step procedure. In particular, dimethyl diazomalonate undergoes this reaction to give 2-aryl-, 2-alkenyl-, or 2-alkyl-4-carbomethoxy-5-methoxy-1,3-oxazoles, and ethyl formyldiazoacetate (diazomalonate half-ester half-aldehyde)
Rhodium(II) acetate catalyzes the reaction of dimethyl diazomalonate with nitriles to give 4-carbomethoxy-5-methoxy-1,3-oxazo1es. Oxazole formation exceeds cyclopropane formation even in cases of conjugated and non-conjugated unsaturated nitriles.
I–-Catalyzed Reaction of 5-Methoxyoxazoles with Organic Iodides – An Efficient Synthesis of Azalactones
作者:Lianghua Lu、Ping Lu、Shengming Ma
DOI:10.1002/ejoc.200600637
日期:2007.2
An I–-catalyzed methoxy carbon–oxygen bond cleavage in 5-methoxyoxazoles leading to the synthesis of azalactones, precursors of quaternary amino acids, has been developed. A series of 4-substituted azalactones were obtained through the variation of the alkyl iodides and differently substituted 5-methoxyoxazoles. Further study indicated that azalactone 3aa may be easily converted to benzoyl-protected