Benzene → (1S,2S) 2-Ethyl-1-(2trimethylsilanylethoxycarbonylamino)cyclopropane-carboxylic acid tert-butyl ester

HRID 1892998Notes

Reaction equation

HRID 1892998 reaction equation
C(OC([C@@]1(N[C:13]([O:15][C:16]([CH3:19])([CH3:18])[CH3:17])=[O:14])C[C@H]1C1CC1)=O)C.CC[N:22]([CH2:25][CH3:26])[CH2:23]C.C1C=CC(P(N=[N+]=[N-])(C2C=CC=CC=2)=[O:34])=CC=1.[CH3:44][Si:45]([CH3:50])([CH3:49])[CH2:46][CH2:47][OH:48].[CH:51]1[CH:56]=CC=C[CH:52]=1>>[C:16]([O:15][C:13]([C@:25]1([NH:22][C:23]([O:48][CH2:47][CH2:46][Si:45]([CH3:50])([CH3:49])[CH3:44])=[O:34])[CH2:26][C@@H:52]1[CH2:51][CH3:56])=[O:14])([CH3:17])([CH3:18])[CH3:19]

Participants

6

Reactant 5

HCID 241BenzeneHCID 8471TriethylamineHCID 180132-(Trimethylsilyl)ethanolHCID 199401P,P-Diphenylphosphinic azideHCID 59990838(1R,2S)-ethyl 1-(tert-butoxycarbonylamino)-2-cyclopropylcyclopropanecarboxylate

Product 1

HCID 86601847(1S,2S) 2-Ethyl-1-(2trimethylsilanylethoxycarbonylamino)cyclopropane-carboxylic acid tert-butyl esterYield 52%

Procedure

To a suspension, of the product of Step 2 (10 g, 46.8 mmol) and 3 g of freshly activated 4 A molecular sieves in dry benzene (160 mL), was added Et3N (7.50 mL, 53.8 mmol) and DPPA (11 mL, 10.21 mmol). The reaction mixture was refluxed for 3.5 h, 2-trimethylsilyl-ethanol (13.5 mL, 94.2 mmol) was then added, and the reaction mixture was refluxed overnight. The reaction mixture was filtered, diluted with Et2O, washed with a 10% aqueous citric acid solution, water, saturated aqueous NaHCO3, water (2×), brine (2×), dried (MgSO4) and concentrated in vacuo. The residue was suspended with 10 g of Aldrich polyisocyanate scavenger resin in 120 mL of CH2Cl2, stirred at rt overnight and filtered to afford the titled product (8 g, 24.3 mmol; 52%) as a pale yellow oil: 1H NMR (CDCl3) δ 0.03 (s, 9H), 0.97 (m, 5H), 1.20 (bm, 1H), 1.45 (s, 9H), 1.40-1.70 (m, 4H), 4.16 (m, 2H), 5.30 (bs, 1H).

Workup

  1. temperatureThe reaction mixture was refluxed for 3.5 h
  2. temperaturethe reaction mixture was refluxed overnight
  3. filtrationThe reaction mixture was filtered
  4. additiondiluted with Et2O
  5. washwashed with a 10% aqueous citric acid solution, water, saturated aqueous NaHCO3, water (2×), brine (2×)
  6. dry with materialdried (MgSO4)
  7. concentrationconcentrated in vacuo
  8. filtrationfiltered

Sources & evidence

ORD record
ord-e61479fea1284338acf47650fecbf87c
Source dataset
uspto-grants-2013_08
Patent number
US08507722B2

Reaction notes

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