Sulfuric Acid → Desmosterol

HRID 1578416Notes

Reaction equation

O[C:2]([CH2:5][CH2:6][CH2:7][C@H:8]([C@@H:10]1[C@:28]2([CH3:29])[C@H:13]([C@H:14]3[C@H:25]([CH2:26][CH2:27]2)[C@:23]2([CH3:24])[C:17]([CH2:18][C@H:19]([CH2:21][CH2:22]2)[OH:20])=[CH:16][CH2:15]3)[CH2:12][CH2:11]1)[CH3:9])([CH3:4])[CH3:3].S(=O)(=O)(O)O.P(Cl)(Cl)(Cl)=O>>[CH3:9][C@@H:8]([C@@H:10]1[C@@:28]2([CH3:29])[CH2:27][CH2:26][C@@H:25]3[C@@:23]4([CH3:24])[CH2:22][CH2:21][C@H:19]([OH:20])[CH2:18][C:17]4=[CH:16][CH2:15][C@H:14]3[C@@H:13]2[CH2:12][CH2:11]1)[CH2:7][CH2:6][CH:5]=[C:2]([CH3:3])[CH3:4]

Participants

Reactant 3

HCID 1118Sulfuric Acid

HCID 24813Phosphorus oxychloride

HCID 6509425-Hydroxycholesterol

Product 1

HCID 439577Desmosterol

Procedure

As the starting material, which is converted to 25-hydroxycholesterol by Grignard reaction, and then dehydrated in the presence of sulfuric acid or phosphorus oxychloride to provide desmosterol or an ester thereof (see J. Org. Chem. 23, p. 459, and J. Lipid Research, 8, p. 152). This method however again has such deficiencies as that the starting 25-ketonorcholesterol is expensive and that the yield of dehydration reaction is low. Particularly when phosphorus oxychloride is used in the reaction, substantial amounts of 25-dehydrocholesterol 3-acetate is produced as a by-product. Thus, the method is not industrially advantageous.

Sources & evidence

ORD record: ord-de163962968245f1a12119055f72a2ca
Source dataset: uspto-grants-1976_02
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US03936478

Reaction notes

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