Michio Shiota

Unusual cyclization of 3,20-bisethylenedioxy-9,11-seco-C-nor-5α-pregnane-9β,11-diol into 11-oxa-5α,17α-pregnane-3,20-dione

On refluxing with a catalytic amount of toluene-p-sulphonic acid in acetone 3,20-bisethylenedioxy-9,11-seco-C-nor-5α-pregnane-9β,11-diol (1) cyclized to give 11-oxa-5α,17α-pregnane-3,20-diene (2), via the transient formation of a hemiacetal.

Cyclization reaction of 3,20-bis(ethylenedioxy)-9,11-seco-C-nor-5α-pregnane-9β,11-diol into 17α-acetyl-11-oxa-C-nor-D-homo-5α-androstan-3-one

3,20-Bis(ethylenedioxy)-11-tosyloxy-9,11-seco-C-nor-5α-pregnane-9β-ol (2) on heating in dimethylformamide was converted into 17α-acetyl-11-oxa-C-nor-D-homo-5α-androstan-3-one (3).

Cyclization of 3,3;20,20-bis(ethylenedioxy)-C-nor-9,11-seco-5α-pregnane-9β,11-diol into 11-oxa-5α,17α-pregnane-3,20-dione

On refluxing with a catalytic amount of toluene-p-sulphonic acid in acetone, 3,3;20,20-bis(ethyl-enedioxy)-C-nor-9,11-seco-5α-pregnane-9β,11-diol (1) cyclized to give 11-oxa-5α,17α-pregnane-3,20-dione (2), via the transient formation of a hemiacetal.

Synthesis of (+)-malyngolide from (+)-tartaric acid

(+)-Malyngolide (+)-(1), the antipode of natural malyngolide, was synthesized in 9 steps from dimethyl (2R,3R)-(–)-tartrate acetonide (3)via(2R)-(–)-2-nonylbutane-1,2,4-triol (8) in 5.1 % overall yield.

Reduction of 5α-Cholestan-3-one with Water as a Hydrogen Donor in the Presence of Precipitated Metals

Reduction of 5α-cholestan-3-one with various precipitated metals using water as a hydrogen donor was investigated. Precipitated cobalt in t-BuOH and nickel in dioxane afforded 5α-cholestan-3α-ol favorably. Some multi-component precipitated metals were found to show high activity.

Synthesis of a Δ5-19-methyl-19-oxo-steroid

19-Methyl-19-oxocholest-5-en-3β-ol acetate has been synthesized from the corresponding 19-methylene derivative.