Stereoselective cyclization of (E)- and (Z)-5,6-dimethyl-8-trimethylsilyl-6-octenals
作者:Kazuhiko Asao、Hideo Iio、Takashi Tokoroyama
DOI:10.1016/s0040-4039(01)93905-x
日期:1989.1
The diastereoselectivities in the acid-mediated cyclization of (E)- and (Z)-5,6-dimethyl-8-trimethylsilyl-6-octenals, both stereoselectively synthesized, were investigated. Excellent preference for the formation ofcis-dimethylcyclohexanols was realized, specially in the case of the (Z)-substrate where they formed exclusively. The selectivity in the hydroxyl group configuration varied in relation with
Convenient Stereoselective Syntheses of (6<i>E</i>)- and (6<i>Z</i>)-5,6-Dimethyl-8-silyl-octenals
作者:Kazuhiko Asao、Hideo Iio、T. Tokoroyama
DOI:10.1055/s-1990-26881
日期:——
A stereoselective synthetic method for the title compounds, E- and Z- allylsilanes, which would be generally applicable for the preparation of other trisubstituted allylsilanes, has been elaborated. The key steps are the following: (i) stereoselective preparation of (2Z)- and (2E)-3-[(diethoxy)phosphoryloxy]-2-octenoates (Z)- and (E)- 4, (ii) substitution of 3-phosphoryloxy group with methyl in the presence of palladium catalyst [(Z/E)-4 → (E/Z)-5]; and (iii) substitution reaction of the desired allyl chlorides with appropriate silyllithiums [(E/Z)-7 → (E/Z)-8].