Acetic Anhydride → (R)-tert-butyl 4-(7-acetoxy-5-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-yl)piperazine-1-carboxylate

HRID 75399Notes

Reaction equation

HRID 75399 reaction equation
[CH3:1][C:2]([O:4][C:5]([CH3:7])=[O:6])=O.[C:8]([O:12][C:13]([N:15]1[CH2:20][CH2:19][N:18]([C:21]2[N:26]=[CH:25][N+:24]([O-])=[C:23]3C[CH2:29][C@@H:30](C)[C:22]=23)[CH2:17][CH2:16]1)=[O:14])([CH3:11])([CH3:10])[CH3:9]>>[C:5]([O:4][CH:2]1[C:23]2[N:24]=[CH:25][N:26]=[C:21]([N:18]3[CH2:19][CH2:20][N:15]([C:13]([O:12][C:8]([CH3:11])([CH3:10])[CH3:9])=[O:14])[CH2:16][CH2:17]3)[C:22]=2[C@H:30]([CH3:29])[CH2:1]1)(=[O:6])[CH3:7]

Participants

3

Reactant 2

HCID 7918Acetic AnhydrideHCID 67338667(R)-4-(4-(tert-butoxycarbonyl)piperazin-1-yl)-5-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidine 1-oxide

Product 1

HCID 59580360(R)-tert-butyl 4-(7-acetoxy-5-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-yl)piperazine-1-carboxylateYield 100%

Conditions

Temperature
90 °C

Procedure

Ac2O (77.0 mL, 816 mmol) was added to (R)-4-(4-(tert-butoxycarbonyl)piperazin-1-yl)-5-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidine 1-oxide (21.0 g, 62.8 mmol). The reaction mixture was heated under nitrogen in a 90° C. sand bath and stirred for 100 minutes. The reaction mixture was cooled to room temperature, and excess acetic anhydride was removed by rotary evaporation. The resulting oil was dissolved in DCM, which was then poured carefully into ice saturated Na2CO3. The mixture was extracted with DCM, and the combined extracts were dried (Na2SO4), filtered and concentrated to give (5R)-tert-butyl 4-(7-acetoxy-5-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-yl)piperazine-1-carboxylate (23.6 g, 100%) as a foam. LC/MS (APCI+) m/z 377.1 [M+H]+.

Workup

  1. temperatureThe reaction mixture was cooled to room temperature
  2. customexcess acetic anhydride was removed by rotary evaporation
  3. dissolutionThe resulting oil was dissolved in DCM
  4. additionwhich was then poured carefully into ice saturated Na2CO3
  5. extractionThe mixture was extracted with DCM
  6. dry with materialthe combined extracts were dried (Na2SO4)
  7. filtrationfiltered
  8. concentrationconcentrated

Sources & evidence

ORD record
ord-c3f30c1b909a42d39923a72f673ca86e
Source dataset
uspto-grants-2014_09
Patent number
US08835434B2

Reaction notes

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