Methyl orthovalerate

Methyl-2-nitrosopropane dimer, 413 1 -Methyl-A8-octahydroquinoline, 111-112 yV-Methyl-A -octahydroquinoline, 111-112 Methyl orthoformate, 47, 54 Methyl orthovalerate, 48 2-Methyl-4-oximino-3-pentanone, 396 1 -(N-Methyl-7V-phenylamino)-2-bromo-propane, 105... 

The valerate is made from betamethasone as a starting material as follows A suspension of 9a-fluoro-1 ip,17a,21-trihydroxy-16/3-methylpregna-1,4-diene-3,20-dione (betamethasone) (2 grams) in sodium dried benzene (500 ml) was distilled vigorously for a few minutes, toluene-p- ulfonic acid monohydrate (30 mg) and methyl orthovalerate (5 ml) were added and distillation was continued for 10 minutes. The mixture was then boiled under reflux for 1.5 hours after which time unreacted betamethasone alcohol (400 mg) was removed by filtration. The benzene solution was treated with solid sodium bicarbonate and a few drops of pyridine, filtered and evaporated to dryness at about 50°C. The residue, in ether, was filtered through grade III basic alumina (20 grams) to remove traces of unreacted betamethasone alcohol, the ether removed in vacuo and the residue of crude betamethasone... 

The method has been applied by the submitters2 to the preparation of cyclohexylmethylpropiolaldehyde diethyl acetal (54% yield) from cyclohexylmethylacetylene and triethyl orthoformate of phenylethynyl n-butyl dimethyl ketal (40% yield) from phenylacetylene and trimethyl -orthovalerate and of phenylethynyl methyl diethyl ketal (34% yield) from phenylacetylene and triethyl orthoacetate. w-B utylpropiolaldehyde diethyl acetal was isolated in 32% yield by heating an equimolar mixture of 1-hexyne and triethyl orthoformate containing catalytic amounts of a zinc chloride-zinc iodide catalyst under autogenous pressure at 190° for 3 hours. 

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