Beilstein J. Org. Chem.2017,13, 795–799, doi:10.3762/bjoc.13.79
Yan Chen Xiaoman Wang Junchang Wang You Yang Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China 10.3762/bjoc.13.79 Abstract A [4 + 3] synthesis of D-manno-heptulose is described. The cascade
aldol/hemiketalization reaction of a C4 aldehyde with a C3 ketone provides the differentially protected ketoheptose building block, which can be further reacted to furnish target D-manno-heptulose.
Keywords: aldol reaction; cascade reaction; D-manno-heptulose; higher-carbon sugar; ketoheptose
; Introduction
D-manno-Heptulose is a rare naturally occurring seven-carbon sugar first isolated from avocado [1], which exhibited promising diabetogenic effects through suppression of the glucose metabolism and insulin secretion via competitive inhibition of the glucokinase pathway [2][3][4][5][6]. Accordingly
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Graphical Abstract
Scheme 1:
Retrosynthetic analysis of D-manno-heptulose.
Beilstein J. Org. Chem.2015,11, 1096–1104, doi:10.3762/bjoc.11.123
efficient and versatile approach towards D-manno-configured C-glycosyl-type glycoconjugates. In our study, we have employed two different amines in the Amadori rearrangement with 8, propargylamine and aniline. Under typical conditions for this reaction [2] 1-progargylamino-1-deoxy-D-manno-heptulose 9 and 1
-phenylamino-1-deoxy-D-manno-heptulose 10 were obtained as pure α-anomers in 77% and 24% yield, respectively (Scheme 3). The low yield of compound 10 may be explained by the low pKa value (4.62) of aniline compared to a pKa of 8.15 for propargylamine, the latter being clearly more efficient as a nucleophile
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Graphical Abstract
Scheme 1:
The Amadori rearrangement of aldoses with amines leads to C-glycosyl-type glycoconjugates, namely 1...