Synthesis of Chrysogeside B from Halotolerant Fungus Penicillium and Its Antimicrobial Activities Evaluation

Abstract

Chrysogeside B, a natural cerebroside, was efficiently synthesized from commercial feedstocks. The bioassays showed that compounds 4, 5 and 6 exhibited enhanced biological activities compared Chrysogeside B. Further studies revealed that free hydroxyl groups and glycosidic bond have significant impact on the antimicrobial activities. The synthesis of Chrysogeside B and analogues designed to allow identification of the features of this glycolipid required for recognition by tested bacteria and Hela cells is described.

Total synthesis of ceramides and β-O-glucosylceramides via intramolecular fatty acyl group migration

“…27 The trichloroacetimidate 7 was prepared from pentaacetyl b-D-glucose 6 by the reported method. 22,28 With both intermediates 2 and 7 in our hand, we then coupled the sphingosine acceptor (2) and excess of imidate donor (7) in a glycosylation reaction using TMSOTf as a promoter at À40 1C, resulting in a nonseparable glycosylated product, along with un-reacted glucosyl donor. The mixture was then subjected to deprotection of the tetrachlorophthalimido (TCP) group under the reported reaction conditions with ethylenediamine.…”

“…19 Total synthesis of 2-deoxyl-b-O-GalCer, and its cytokine response was studied in Type I and II NKT cell hybridomas. 20 b-O-GalCer was synthesized by joining a-galactosyl iodide with stannyl sphingosine/ceramides in the presence of BF 3 ÁEt 2 O, 21 protected sphingosine/ceramide coupled with glycosyl trichloroacetimidate donor using the TMSOTf, 22,23 AgOTf 24,25 or BF 3 ÁEt 2 O 26 mediated glycosylation reaction as a key step.…”

A Sphingolipid Fatty Acid Constituent Made by Alkyne trans‐Hydrogenation: Total Synthesis of Symbioramide

“…In consideration of these many opportunities, we were confident that the original failure in the trans ‐reduction of 11 [27] can be overcome. While other authors have already been successful in doing so simply by replacing (EtO) 3 SiH by the more reactive (EtO)Me 2 SiH, [42,43] we conjectured that trans ‐hydrogenation provides an even better solution (Scheme 1). If successful, proto‐desilylation of an alkenylsilane of type 12 could be avoided, which will save steps and make the route more atom‐economical.…”