Seven-Step Total Synthesis of Sporothriolide.

An enantioselective total synthesis of sporothriolide, a bioactive furofurandione-type fungal metabolite, has been achieved in a 21% overall yield from a commercially available ß,γ-unsaturated carboxylic acid via seven steps. The key steps of this synthesis include a highly diastereoselective Michael addition of a chiral oxazolidinone derivative to a nitro olefin, the exploitation of an aromatic ring as a masked carboxylic acid functionality, and the base-promoted elimination of nitrous acid to install the α-methylene lactone unit of sporothriolide in the final step.

Synthesis of a plasmenylethanolamine.

A concise synthesis of a plasmenylethanolamine (PlsEtn-[16:0/18:1 n-9]), known as antioxidative phospholipids commonly found in cell membranes, has been achieved from an optically active known diol through 8 steps. The key transformations for the synthesis of PlsEtn-[16:0/18:1 n-9] are (1) regio- and Z-selective vinyl ether formation via the alkylation of a lithioalkoxy allyl intermediate with an alkyl iodide, and (2) a one-pot phosphite esterification-oxidation sequence to construct the ethanolamine phosphonate moiety in the presence of the vinyl ether functionality. The piperidine salt of synthetic PlsEtn-[16:0/18:1 n-9] was desalinated through reversed-phase high-performance liquid chromatography purification.

Isolation and structural elucidation of unique γ-oryzanol species in rice bran oil.

Even though γ-oryzanol (OZ) such as 24-methylenecycloartanyl ferulate (24MCAFA) is abundant in purified rice bran oil, we realized that the oil contained the prospect of two additional novels of OZ species. To identify this, we isolated and analyzed their chemical structures by using HPLC-UV-MS, NMR, and IR. We revealed for the first time that the oil had also contained cyclobranyl ferulate (CBFA) and cyclosadyl ferulate (CSFA) which are likely to be exist due to the isomerism of 24MCAFA under acid condition. OZ profile including CBFA and CSFA was roughly similar between commercial rice bran oils and processed foods containing the oils, suggesting that people might have often consumed CBFA and CSFA from rice bran oils and/or processed foods. Since different OZ species are known to have different functionality, this study opens the chance to explore more the contribution of CBFA and CSFA for human health and wellness.

Stereocontrolled Total Synthesis of (-)-Isocelorbicol and Its Elaboration to Natural Dihydro-ß-agarofuran Esters.

The first total synthesis of four naturally occurring dihydro-ß-agarofuran esters has been accomplished via a highly stereocontrolled 14-step access to their common core triol, (-)-isocelorbicol. A semipinacol rearrangement of an epoxy alcohol to install a quaternary carbon, diastereoselective conjugate reduction of a spirocyclic butenolide for the establishment of a methyl-bearing chiral center, and ring-closing metathesis to construct the decalin ring system were exploited as the key steps for the high-yielding synthesis of (-)-isocelorbicol.

Author Correction: Definitive evidence of the presence of 24-methylenecycloartanyl ferulate and 24-methylenecycloartanyl caffeate in barley.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Definitive evidence of the presence of 24-methylenecycloartanyl ferulate and 24-methylenecycloartanyl caffeate in barley.

γ-Oryzanol (OZ), which has a lot of beneficial effects, is a mixture of ferulic acid esters of triterpene alcohols (i.e., triterpene alcohol type of OZ (TTA-OZ)) and ferulic acid esters of plant sterols (i.e., plant sterol type of OZ (PS-OZ)). Although it has been reported that OZ is found in several kinds of cereal typified by rice, TTA-OZ (e.g., 24-methylenecycloartanyl ferulate (24MCA-FA)) has been believed to be characteristic to rice and has not been found in other cereals. In this study, we isolated a compound considered as a TTA-OZ (i.e., 24MCA-FA) from barley and determined the chemical structure using by HPLC-UV-MS, high-resolution MS, and NMR. Based on these results, we proved for the first time that barley certainly contains 24MCA-FA (i.e., TTA-OZ). During the isolation and purification of 24MCA-FA from barley, we found the prospect that a compound with similar properties to OZ (compound-X) might exist. To confirm this finding, the compound-X was also isolated, determined the chemical structure, and identified as a caffeic acid ester of 24-methylenecycloartanol (24MCA-CA), which has rarely been reported before. We also quantified these compounds in various species of barley cultivars and found for the first time the existence of 24MCA-FA and 24MCA-CA in various barley. Through these findings, it opens the possibility to use barley as a new source of 24MCA-FA and 24MCA-CA.