A New Access to 16-Membered Macrocycles: Synthesis of the Model COD Ring System of Vancomycin

S Ghosh, AS Kumar, GN Mehta, R Soundararajan

Index: Ghosh, Samir; Kumar, A. Sanjeev; Mehta; Soundararajan Synthesis, 2009 , # 19 p. 3322 - 3326

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Abstract

Commercially obtained l-tyrosine was esterified using thionyl chloride in methanol under reflux to afford l-tyrosine methyl ester (2). Then, Boc-protected (R)-phenylglycine 3 was coupled with l-tyrosine methyl ester (2) using N-ethyl-N′-(3-dimethylaminopropyl)carbodiimide hydrochloride (1.5 equiv), 1-hydroxybenzotriazole (1 equiv), and N,N-diisopropylethylamine (3 equiv) as a base in dichloromethane at 25 ˚C for 2 hours to afford compound 4 in 90% yield (Scheme ...