Toluene → tert-Butyl hepta-1,6-diyn-4-ylcarbamate
Reaction equation
C([N:3]([CH2:6]C)CC)C.C1(P(N=[N+]=[N-])(C2C=CC=CC=2)=[O:15])C=CC=CC=1.[C:25]([OH:29])([CH3:28])([CH3:27])[CH3:26].[C:30]1([CH3:36])[CH:35]=[CH:34][CH:33]=[CH:32][CH:31]=1>>[C:25]([O:29][C:6]([NH:3][CH:32]([CH2:33][C:34]#[CH:35])[CH2:31][C:30]#[CH:36])=[O:15])([CH3:28])([CH3:27])[CH3:26]Participants
5
Procedure
Triethylamine (19.5 g, 0.193 mol) was added to a solution of 2-(propyn-2-yl)-4-pentynoic acid (34, 25.0 g, 0.184 mol; J. Chem. Soc., Perkin Trans. I, 1215-1224 (1986)) in toluene (200 ml) with cooling. Diphenylphosphoryl azide (50.3 g, 0.184 mol) was added, and the mixture was stirred at room temperature for 15 minutes and heated on the steam bath until the evolution of gas ceased. Dry t-butanol (150 ml) was added, and the mixture was heated on the steam bath for 24 hours. The solvent was removed under vacuum, and the mixture was diluted with water and extracted twice with diethylether. The combined extracts were washed twice with 10% sodium carbonate solution and once with brine. The solution was dried (MgSO4), and the solvent was removed under vacuum to leave a solid. Purification by flash chromatography on silica gel eluting with ethyl acetate/hexane gave a white solid which was crystallized from hexane to give 4-(t-butyloxycarbonylamino)heptan-1,6-diyne as colorless crystals (m.p. 64-67° C.).