- Synthesis of β-amino α-hydroxy carboxylic esters from oxiranecarboxylic esters
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3-Aryl-3-azido-2-hydroxypropanoic esters, prepared from the corresponding 3-aryl-oxirane-2-carboxylic esters by ring opening with sodium azide, were reduced with tin(II) chloride dihydrate in methanol to give 3-amino-3-aryl-2-hydroxypropanoic esters in good yields.Under these conditions, halogen substituents in the aromatic rings were not affected.The nitro group, however, was partially reduced to the amino group.Treatment of aliphatic oxirane-2-carboxylic esters with acetonitrile in the presence of boron trifluoride etherate led to regiospecific formation of 2,4-dialkyl-2-oxazoline-5-carboxylic esters, resulting from reaction of the nitrile at C3.Acidic hydrolysis of these oxazoline-5-carboxylic esters gave the corresponding 3-(acylamino)-2-hydroxy carboxylic esters.With these two complementary methods, both aryl- and alkyl-substituted β-amino α-hydroxy acid derivatives are accessible.
- Legters, Johan,Dienst, Erik van,Thijs, Lambertus,Zwanenburg, Binne
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- Highly stereoselective synthesis of α-hydroxy β-amino acids through β-lactams: Application to the synthesis of the taxol and bestatin side chains and related systems
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Formation of α-hydroxy β-lactams, followed by chemical elaboration at C4 and further β-lactam cleavage afforded functionalised α-hydroxy β-amino acids or their derivatives in a highly stereoselective manner.
- Palomo,Arrieta,Cossio,Aizpurua,Mielgo,Aurrekoetxea
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p. 6429 - 6432
(2007/10/02)
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