Abstract
Two partial syntheses of bufotalin (1a) were developed as follows. The 16-ketone 3 was prepared from cinobufagin and the 14,15β-epoxide group was reduced with chromous acetate to yield β-hydroxy ketone 4 (61%) and α,β-unsaturated ketone 5 (27%). Selective reduction of β-ketone 4 with Urushibara nickel A afforded alcohol 1b, which was acetylated to provide diacetate 1c. Treatment of diacetate 1c with hydrochloric acid in methanol gave bufotalin (1a) accompanied by lesser amounts of other hydrolysis products (1b, 1d, and 6a). In an alternative approach, α,β-unsaturated ketone 5 was first reduced with Urushibara nickel A to allylic alcohol 6a. After acetylation (to 6b) the olefin was subjected to reaction with hypoiodous acid or hypobromous acid and the resulting halohydrin (7a or 7b) was treated with Urushibara nickel A. The product of hydrogenolysis was bufotalin 3β-acetate (1c).
| Original language | English (US) |
|---|---|
| Pages (from-to) | 3007-3010 |
| Number of pages | 4 |
| Journal | Journal of Organic Chemistry |
| Volume | 39 |
| Issue number | 20 |
| State | Published - 1974 |
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ASJC Scopus subject areas
- Organic Chemistry
Cite this
Bufadienolides. 29. Synthetic routes to bufotalin. / Kamano, Yoshiaki; Pettit, George; Inoue, Masuo.
In: Journal of Organic Chemistry, Vol. 39, No. 20, 1974, p. 3007-3010.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Bufadienolides. 29. Synthetic routes to bufotalin
AU - Kamano, Yoshiaki
AU - Pettit, George
AU - Inoue, Masuo
PY - 1974
Y1 - 1974
N2 - Two partial syntheses of bufotalin (1a) were developed as follows. The 16-ketone 3 was prepared from cinobufagin and the 14,15β-epoxide group was reduced with chromous acetate to yield β-hydroxy ketone 4 (61%) and α,β-unsaturated ketone 5 (27%). Selective reduction of β-ketone 4 with Urushibara nickel A afforded alcohol 1b, which was acetylated to provide diacetate 1c. Treatment of diacetate 1c with hydrochloric acid in methanol gave bufotalin (1a) accompanied by lesser amounts of other hydrolysis products (1b, 1d, and 6a). In an alternative approach, α,β-unsaturated ketone 5 was first reduced with Urushibara nickel A to allylic alcohol 6a. After acetylation (to 6b) the olefin was subjected to reaction with hypoiodous acid or hypobromous acid and the resulting halohydrin (7a or 7b) was treated with Urushibara nickel A. The product of hydrogenolysis was bufotalin 3β-acetate (1c).
AB - Two partial syntheses of bufotalin (1a) were developed as follows. The 16-ketone 3 was prepared from cinobufagin and the 14,15β-epoxide group was reduced with chromous acetate to yield β-hydroxy ketone 4 (61%) and α,β-unsaturated ketone 5 (27%). Selective reduction of β-ketone 4 with Urushibara nickel A afforded alcohol 1b, which was acetylated to provide diacetate 1c. Treatment of diacetate 1c with hydrochloric acid in methanol gave bufotalin (1a) accompanied by lesser amounts of other hydrolysis products (1b, 1d, and 6a). In an alternative approach, α,β-unsaturated ketone 5 was first reduced with Urushibara nickel A to allylic alcohol 6a. After acetylation (to 6b) the olefin was subjected to reaction with hypoiodous acid or hypobromous acid and the resulting halohydrin (7a or 7b) was treated with Urushibara nickel A. The product of hydrogenolysis was bufotalin 3β-acetate (1c).
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M3 - Article
VL - 39
SP - 3007
EP - 3010
JO - Journal of Organic Chemistry
JF - Journal of Organic Chemistry
SN - 0022-3263
IS - 20
ER -