Synthesis of analogues of linckoside B, a new neuritogenic steroid glycoside

Total Synthesis of Linckosides A and B, the Representative Starfish Polyhydroxysteroid Glycosides with Neuritogenic Activities

“…However, the poor accessibility of these molecules from natural sources has retarded in-depth studies on their activities. Chemical synthesis to attain these highly polar, fragile, and complex steroid glycosides poses also a formidable challenge; , to the best of our knowledge, none of the starfish polyhydroxysteroid glycosides has ever been synthesized to date. , …”

“…Chemical synthesis to attain these highly polar, fragile, and complex steroid glycosides poses also a formidable challenge; 3,4 to the best of our knowledge, none of the starfish polyhydroxysteroid glycosides has ever been synthesized to date. 4,5 We envisioned the assembly of linckoside A/B from four pieces (Figure 1), including a polyhydroxysteroid C22 aldehyde (e.g., 3), a side chain derivative (e.g., 4), a 2-O-methyl-Dxylopyranosyl donor (e.g., 5), and an L-arabinofuranosyl/Dxylopyranosyl donor (e.g., 6/7). The polyhydroxysteroid aldehyde (3) could be elaborated from the easily accessible vespertilin acetate 8 6 by exploiting the inherent functional groups at C3, C5/6, C16, and C22.…”

Chemical Synthesis of Saponins

“…170, 175 In the past few decades, total syntheses of starfish saponins and their analogues have attracted much interest from carbohydrate chemists. 48,50,[176][177][178] In 1993, the Schmidt group reported the synthesis of sulfated steroid glycoside forbeside E1 (383), isolated from the starfish Asterias forbesi Desor (Scheme 57). 176,179 11-Oxoprogesterone (384) was transformed into the 3-OTBS-6-OH aglycone acceptor 385 in eight steps and 14% overall yield.…”

Highly Selective Hydrogenation of R-(+)-Limonene to (+)-p-1-Menthene in Batch and Continuous Flow Reactors

“…The production of the partially hydrogenated product, (+)- p -1-menthene, has been of particular interest since it is an attractive intermediate due to the retention of the chiral center and the presence of a double bond which can be further functionalized. Indeed, (+)- p -1-menthene has been widely used as a starting material for the synthesis of bulk (e.g., additives for adhesives, coatings, food) and fine chemicals (e.g., steroids, antimalaria agent, menthol). − Furthermore, the fully hydrogenated products from (+)- p -1-menthene, p -menthanes, have been shown to be promising biobased fuel additives. , …”

“…Therefore, the study of selective hydrogenation of monoterpenes, which has industrial relevant applications as shown above, has attracted several studies. The partial hydrogenation of limonene has been subjected to different studies and was performed in media as different as MeOH, EtOH, heptane, benzene, and recently supercritical CO 2 . ,− Beside molecular hydrogen, reducing agents such as hydrazine and alcohols have also been reported. − In general, two possible reaction pathways have been identified for the hydrogenation of limonene (Scheme ). The preferred reaction pathway involves reduction of the terminal CC bond to form (+)- p -1-menthene, independently from the nature of the catalyst and the hydrogen source.…”