Use of the Benzyl Mesylate for the Synthesis of Tetrahydrofuran Lignan: Syntheses of 7,8-<i>trans</i>, 7′,8′-<i>trans</i>, 7,7′-<i>cis</i>, and 8,8′-<i>cis</i>-Virgatusin Stereoisomers
The benzyl mesylate was employed to construct the tetrasubstituted tetrahydrofuran lignan with avoiding Friedel-Crafts type of reaction. The optically pure 7,8-trans, 7′,8′-trans, 7,7′-cis, and 8,8′-cis-virgatusin stereoisomers were synthesized. The enantiomeric excess was >>99%.
(1S,2S,5R,6S )-6-(3,4-Methylenedioxyphenyl)-3,7-dioxabicyclo[3.3.0]octan-1,2-diol ((+)-1-hydroxysamin 1) was synthesized, starting from olefin 8. Stereoselective α-hydroxylation was achieved after converting 8 to aldehyde 13. Resulting unstable α-hydroxy aldehyde 14 was then transformed to (+)-1-hydroxysamin (1). This is a new efficient synthetic route to 1,2-oxygenated 6-arylfurofuran lignans.