Picolyl chloride → 2-Pyridin-2-ylmethyl-piperazine-1,2,4-tricarboxylic acid 1-benzyl ester 4-tert-butyl ester 2-methyl ester

HRID 2304044Notes

Reaction equation

HRID 2304044 reaction equation
[CH3:1][O:2][C:3]([CH:5]1[CH2:10][N:9]([C:11]([O:13][C:14]([CH3:17])([CH3:16])[CH3:15])=[O:12])[CH2:8][CH2:7][N:6]1[C:18]([O:20][CH2:21][C:22]1[CH:27]=[CH:26][CH:25]=[CH:24][CH:23]=1)=[O:19])=[O:4].C[Si]([N-][Si](C)(C)C)(C)C.[K+].[N:38]1[CH:43]=[CH:42][CH:41]=[CH:40][C:39]=1[CH2:44]Cl.C(=O)(O)[O-].[Na+]>O1CCCC1.C(Cl)Cl.CN(C=O)C>[CH3:1][O:2][C:3]([C:5]1([CH2:44][C:39]2[CH:40]=[CH:41][CH:42]=[CH:43][N:38]=2)[CH2:10][N:9]([C:11]([O:13][C:14]([CH3:17])([CH3:15])[CH3:16])=[O:12])[CH2:8][CH2:7][N:6]1[C:18]([O:20][CH2:21][C:22]1[CH:27]=[CH:26][CH:25]=[CH:24][CH:23]=1)=[O:19])=[O:4]

Participants

8

Reactant 4

HCID 23393Picolyl chlorideHCID 516892Sodium BicarbonateHCID 3251421Potassium bis(trimethylsilyl)amideHCID 44519651-Benzyl 4-tert-butyl 2-methyl piperazine-1,2,4-tricarboxylate

Product 1

HCID 539190472-Pyridin-2-ylmethyl-piperazine-1,2,4-tricarboxylic acid 1-benzyl ester 4-tert-butyl ester 2-methyl ester

Reagents, catalysts & solvents 3

HCID 6228DimethylformamideSolventHCID 6344DichloromethaneSolventHCID 8028TetrahydrofuranSolvent2×

Procedure

A stirred solution of piperazine-1,2,4-tricarboxylic acid 1-benzyl ester 4-tert-butyl ester 2-methyl ester (200 g, 529 mol), prepared as described by Bigge et al. (Tetrahedron Let 1989, 30, 5193), in tetrahydrofuran (200 mL) and DMF (1.5 L) was cooled to about −78° C., and a 0.5 M solution of potassium bis(trimethylsilyl)amide in THF (1.27 L) was added. After the above solution had stirred for about one hour, the free base of 2-picolyl chloride was generated by extracting the corresponding hydrochloride salt (217 g, 1.32 mol) from saturated sodium bicarbonate solution with methylene chloride. The combined organic extracts were dried (MgSO4), concentrated, immediately dissolved in DMF (100 mL), and then added dropwise to the enolate containing solution. The reaction was stirred for about 4 hours at about −78° C., then slowly warmed to room temperature and stirred overnight. The toluene and THF were removed under reduced pressure. The residue was extracted from water (1.5 L) with ethyl acetate (3×1 L), the combined extracts were then washed with water (1.5 L), dried (MgSO4) and then concentrated in vacuo to give 240 g of crude product of the title compound of part 3-A which was carried on to the next step: +APcI MS (M+H)+ 470, (M−tBu+H) 436; 1H NMR=400 MHz (methanol-d4) δ: 8.4 (arom, m, 1H), 7.65-7.2 (arom, m, 7H), 6.94 (arom, m, 1H), 5.18 (CbzNCHH, m, 1H), 5.05 (CbzNCHH, m, 1H), 2.54 (m, 1H), 1.41 (Boc, s, 9H).

Workup

  1. dry with materialThe combined organic extracts were dried (MgSO4)
  2. concentrationconcentrated
  3. dissolutionimmediately dissolved in DMF (100 mL)
  4. additionadded dropwise to the enolate containing solution
  5. stirringThe reaction was stirred for about 4 hours at about −78° C.
  6. stirringstirred overnight
  7. customThe toluene and THF were removed under reduced pressure
  8. extractionThe residue was extracted from water (1.5 L) with ethyl acetate (3×1 L)
  9. washthe combined extracts were then washed with water (1.5 L)
  10. dry with materialdried (MgSO4)
  11. concentrationconcentrated in vacuo

Sources & evidence

ORD record
ord-73bb86d386684e0db74e094321fd0494
Source dataset
uspto-grants-2002_08
Patent number
US06433171B1

Reaction notes

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