Rearrangement Approaches to Cyclic Skeletons. X. Pinacol-Type Rearrangement of 2-Substituted 1-Methoxybicyclo[2.2.2]oct-5-en-2-ols into Bicyclo[3.2.1]oct-6-en-2-ones. Remarkable Substituent Effects on Predominant Migration of the Unsaturated Bridge
作者:Tadao Uyehara、Toshihiro Inayama、Toshiaki Furuta、Tadahiro Kato、Yoshinori Yamamoto、Masako Ueno、Toshio Sato
DOI:10.1246/bcsj.69.1727
日期:1996.6
Pinacol-type rearrangement of 2-substituted 1-methoxybicyclo[2.2.2]oct-5-en-exo-2-ols (1) by treatment with p-toluenesulfonic acid in boiling benzene gave bicyclo[3.2.1]oct-6-en-2ones (2) and -3en-2-ones (4) in a ratio of ≥ 10 to 1 along with small amounts of dehydration products. Treatment of the endo isomers (3) under the same conditions gave 2, 4, and the dehydration products. The ratios of 2 to
Rearrangement Approaches to Cyclic Skeletons. XII. Acid-Catalyzed Isomerization of Bicyclo[3.2.1]oct-6-en-2-ones into Bicyclo[3.2.1]oct-3-en-2-ones without Racemization
The treatment of a bicyclo[3.2.1]oct-6-en-2-one (3) with Amberlyst® (H-15) in boiling benzene gave a mixture of bicyclo[3.2.1]oct-3-en-2-one (5) and bicyclo[2.2.2]oct-5-en-2-one (6). The ratio of 5 to 6 was influenced by the substituent at the C-1 position of the ketone 3. Chiral ketones 3 were transformed into the chiral α,β-unsaturated ketones 5 without racemization.