Acetic Anhydride → 9-Acetyloxy-5a,5b,8,8,11a-pentamethyl-1-prop-1-en-2-yl-1,2,3,4,5,6,7,7a,9,10,11,11b,12,13,13a,13b-hexadecahydrocyclopenta[a]chrysene-3a-carboxylic acid

HRID 2303528Notes

Reaction equation

HRID 2303528 reaction equation
[CH3:1][C:2]([C@H:4]1[C@@H:8]2[C@@H:9]3[C@@:22]([CH3:25])([CH2:23][CH2:24][C@@:7]2([C:31]([OH:33])=[O:32])[CH2:6][CH2:5]1)[C@@:21]1([CH3:26])[C@@H:12]([C@:13]2([CH3:30])[C@@H:18]([CH2:19][CH2:20]1)[C:17]([CH3:28])([CH3:27])[C@@H:16]([OH:29])[CH2:15][CH2:14]2)[CH2:11][CH2:10]3)=[CH2:3].[O:34](C(C)=O)[C:35]([CH3:37])=O>CN(C)C1C=CN=CC=1.C(Cl)Cl>[CH3:3][C:2]([CH:4]1[CH:8]2[CH:9]3[C:22]([CH3:25])([CH2:23][CH2:24][C:7]2([C:31]([OH:33])=[O:32])[CH2:6][CH2:5]1)[C:21]1([CH3:26])[CH:12]([C:13]2([CH3:30])[CH:18]([CH2:19][CH2:20]1)[C:17]([CH3:27])([CH3:28])[CH:16]([O:29][C:35]([CH3:37])=[O:34])[CH2:15][CH2:14]2)[CH2:11][CH2:10]3)=[CH2:1]

Participants

5

Reactant 2

HCID 7918Acetic AnhydrideHCID 64971Betulinic Acid

Product 1

HCID 2899849-Acetyloxy-5a,5b,8,8,11a-pentamethyl-1-prop-1-en-2-yl-1,2,3,4,5,6,7,7a,9,10,11,11b,12,13,13a,13b-hexadecahydrocyclopenta[a]chrysene-3a-carboxylic acid

Reagents, catalysts & solvents 2

HCID 142844-(Dimethylamino)pyridineCatalystHCID 6344DichloromethaneSolvent

Procedure

Betulinic acid, 100 mg (0.22 mmoles) was added to a solution containing 4 mg of 4-dimethylaminopyridine (DMAP) and 0.5 ml of (CH3CO)2O in 5 ml of CH2Cl2. After 2 hrs CH2Cl2 was removed in vacuo, and the remaining residue stirred with 25 ml of water. During the stirring enough of K2CO3 was added to decompose. an excess of acetic anhydride, after which the reaction mixture was extracted with 25 ml of CH2Cl2. The extract was evaporated to dryness and the resulting solid crystallized from MeOH to give 104 mg of acetylbetulinic acid as white crystals, m.p. 285° C.

Workup

  1. customAfter 2 hrs CH2Cl2 was removed in vacuo
  2. additionDuring the stirring enough of K2CO3 was added
  3. extractionan excess of acetic anhydride, after which the reaction mixture was extracted with 25 ml of CH2Cl2
  4. customThe extract was evaporated to dryness
  5. customthe resulting solid crystallized from MeOH

Sources & evidence

ORD record
ord-3f4ceccc8fe94d62bd449ca2b522972b
Source dataset
uspto-grants-2002_08
Patent number
US06433010B1

Reaction notes

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