Beilstein J. Org. Chem.2013,9, 2620–2624, doi:10.3762/bjoc.9.296
, Boston, MA 02215, United States 10.3762/bjoc.9.296 Abstract We completed a new and efficient synthesis of D-chalcose (I) and the first synthesis of its C-3 epimer (I′) in nine steps with overall yields of 23% and 24%, respectively. The key steps in the sequence were the formation of the stereocenter on
-10-camphorsulfonic acid (CSA) in MeOH.
Keywords: asymmetric dihydroxylation; chalcose; epimer; total synthesis; Introduction
Chalcose (4,6-dideoxy-3-O-methyl-D-xylo-hexose, I [1][2]) is a structural component of many macrolide antibiotics, such as chalcomycin [3], neutramycin [4], and lankamycin [5
] (Scheme 1). After its structure was determined using chemical degradation and spectroscopic analyses, several syntheses of chalcose were reported. The conversion of desosamine into D-chalcose was described by Westwood’s group [6]. A small number of stereospecific syntheses beginning from carbohydrate
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Graphical Abstract
Scheme 1:
Retrosynthesis of I and I'. PG = protecting group; protecting groups may vary independently.