Samin type lignan

Yamauchi et al. completed an ex-chiral pool synthesis of a samin-type lignan, Scheme (38) [102]. The diprotected tetraol 230 was obtained from Z-glutammic acid by a 15 step procedure in 7-8% overall yield [103]. The diprotected tetraol 230 was treated with boron trifluoride diethyl etherate in dichloromethane to give the tetrahydrofuran 231 in 84%-87% yield. After deprotection with tetrabutylammonium fluoride, the resulting diol was oxidized by dihydridotetrakis(triphenylphospine)ruthenium(II) to provide two lactones 232 and 233 in a ratio of 2 1. Lactone 232 was transformed in samin-type lignan 234 by diisobutylaluminium hydride reduction in 70% yield. 

Scheme (38). Asymmetric synthesis of samin-type lignan by Yamauchi...

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See also in sourсe #XX -- [ ]

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