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I. Synthesis of specifically substituted D-mannitol derivatives. II. A color precursor isolated from Western Hemlock wood.

University of British Columbia

D-Mannitol was simultaneously tritylated and acetylated to give 1,6-di-0-trityl-D-mannitol tetraacetate in 70% yield, using a procedure that gave a product completely free from triphenylcarbinol. Direct tritylation of D-mannitol yielded 1,6-di-O-trityl-D-mannitol which was crystallized, probably as a solvated molecule, from alcohol and water. Acetylation of this compound gave 1,6-di-0-trityl-D-mannitol tetraacetate in good yield. Detritylation of 1,6-di-O-trityl-D-mannitol tetraacetate to D-mannitol-2,3,4,5-tetraacetate was effected by hydrogen bromide in glacial acetic acid, catalytic hydrogenolysis over platinum oxide, and refluxing with dilute acetic acid, and the latter convenient method was found to give the highest yield of pure product. A sirupy di-O-methyl-D-mannitol was prepared from D-raannitol-2,3,4,5-tetraacetate by methylation followed by deacetylation on an ion exchange column. The structure of is this compound has not been established. A nearly colorless, amorphous solid was isolated in 2.7% yield by 50% aqueous ethanol extraction of the finely-divided wood of a Western Hemlock tree (Tsuga heterophylla) which had previously been exhaustively extracted with benzene. Treatment of this material with concentrated hydrochloric acid in methanol yielded a purple solid whose red-violet methanol solution was stable to ordinary light. The paper chromatographic behaviour and color reactions compared with a red rose petal extract and the methoxyl content indicated that the purple solid was probably an anthocyanidin containing methoxyl groups. Acetylation of the original solid extract with pyridine and acetic anhydride gave a dextrorotatory yellow sirup soluble in chloroform.

Text

2012-02-02

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http://hdl.handle.net/2429/40454

Chemistry

University of British Columbia

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