Palladium-Catalyzed Divergent Imidoylative Cyclization of Multifunctionalized Isocyanides: Tunable Access to Oxazol-5(4<i>H</i>)-ones and Cyclic Ketoimines
Oxazol-5(4H)-one derivatives were obtained exclusively when allyl-2-benzyl(or allyl)-2-isocyanoacetates were used in the reaction with aryl triflates as electrophiles, whereas cyclic ketoimines were generated in the presence of aryl iodides with the allylester group remaining unreacted. The reactions proceeded smoothly under mild conditions with a wide functional group tolerance.
Synthesis of N-acyl-N,α,α-trialkyl and N-acyl-α,α-dialkyl glycines by selective cleavage of Ugi–Passerini adducts. Qualitative assessment of the effect of substituents on the path and yield of reaction
作者:Wei-Qun Jiang、Susana P. G. Costa、Hernâni L. S. Maia
DOI:10.1039/b307111c
日期:——
symmetric N-acyl-N,alpha,alpha-trialkyl glycine amides were synthesised by the Ugi-Passerini four-component reaction and subjected to selective cleavage with trifluoroacetic acid. In almost all cases it was possible to obtain the corresponding N-acyl-N,alpha,alpha-trialkyl and N-acyl-alpha,alpha-dialkyl glycines in fair to good yields directly from the reaction adducts. With some of the bulkier compounds
BEMP-Promoted C(4)-Alkylation of 4-Alkyloxazol-5(4H)-ones: A Rapid and Efficient Route to α,α-Dialkyl-α-amino Acids
作者:Byeong-Seon Jeong、Yeon-Ju Lee、Jeyoung Seo、Dong-Guk Kim、Hyeung-geun Park
DOI:10.1055/s-0032-1317801
日期:——
Rapid and efficient C(4)-alkylation of 4-alkyloxazol-5(4H)-ones has been achieved by the utilization of BEMP as base. 4,4-Dialkyloxazol-5(4H)-ones, which can easily be hydrolyzed into free alpha,alpha-dialkyl-alpha-amino acids, were obtained in high yields (up to 99%) within a few minutes (1-18 min). BEMP, a sterically hindered strong base with low nucleophilicity facilitated the desired reaction, while decreasing the rate of side reactions such as O-alkylation, C(2)-alkylation and the breakage of oxazolone.