Diisopropylamine → 2-(Pyrrolidin-2-ylidenemethyl)-1-Pyrroline

To a solution of diisopropylamine (11.1 g, 109.7 mmol) in THF (200 mL) was dropwise added n-BuLi (2.89 M, 37.97 mL, 109.7 mmol) at −78° C. under nitrogen. Once all the n-BuLi was added, the temperature was adjusted to −5° C., and the reaction mixture was stirred for 30 min. Then a solution of 2-methyl-1-pyrroline (5.65 g, 67.9 mmol) in THF (15 mL) was added dropwise to the reaction mixture at −5° C., and then stirred. After 30 min, 2-methylthio-1-pyrroline (6.02 g, 52.3 mmol) was added dropwise over 30 min at −78° C. The reaction mixture was stirred as the temperature was allowed to gradually rise to room temperature, and was continuously stirred at room temperature overnight. THF solvent was removed under reduced pressure, then 50 mL of methanol was added dropwise to the residue. After removing all of the volatile solvent, pentane (2×100 mL) was added to the residue, and the mixture was filtered. Concentration of the filtrate under reduced pressure, followed by vacuum distillation (65° C. at 110 mTorr), delivered 6.29 of product (79%). 1H NMR (CD2Cl2, 500 MHz): δ 7.89 (s, br, 1H), 4.65 (s, 1H), 3.64 (t, 2H, J=7.2 Hz), 2.51 (t, 2H, J=8.0 Hz), 1.85 (m, 2H). 13C NMR (CD2Cl2, 125 MHz): δ 167.0, 81.7, 53.7, 34.8, 23.2.

1. customat −78° C.
2. customwas adjusted to −5° C.
3. stirringstirred
4. waitAfter 30 min
5. stirringThe reaction mixture was stirred as the temperature
6. customto gradually rise to room temperature
7. stirringwas continuously stirred at room temperature overnight
8. customTHF solvent was removed under reduced pressure
9. addition50 mL of methanol was added dropwise to the residue
10. customAfter removing all of the volatile solvent, pentane (2×100 mL)
11. additionwas added to the residue
12. filtrationthe mixture was filtered
13. distillationConcentration of the filtrate under reduced pressure, followed by vacuum distillation (65° C. at 110 mTorr)

ORD record

ord-1bdfb7901ccb47eaa6324bdee0b5aebb

Source dataset

uspto-grants-2009_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07619107B2