BEMP-promoted C(4)-alkylation of 4-alkyloxazol-5(4 H)-ones: A rapid and efficient route to α,α-dialkyl-α-amino acids
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 α,α-dialkyl-α-amino acids, were obtained in high yields (up to 99%
A reinvestigation of the α-alkylation of 4-monosubstituted 2-phenyloxazol-5(4H)-ones ('azlactones'): A general entry into highly functionalized α,α-disubstituted α-amino acids
Novel, more reliable and general reaction conditions for the α-alkylation of 4-monosubstituted 2-phenyloxazol-5(4H)-ones (= 4-monosubstituted 2-phenyl-azlactones) rac-2 to 4,4-disubstituted 2-phenyloxazol-5(4H)-ones rac-1 were found. Thus, a whole range of highly functionalized rac-1 were prepared in medium-to-good overall yields (40-90%). Azlactones rac-1 are ideal precursors for the synthesis of optically pure α,α-disubstituted (R)- and (S)-α-amino acids.
Obrecht,Bohdal,Ruffieux,Muller
p. 1423 - 1429
(2007/10/02)
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