Réaction #51641

Équation de réaction

bisulfite

pyrrolidine

benzyl bromide

bromotetralone

→

1-(1(RS)-Benzyl-6-bromo-3,4-dihydro-1H-naphthalen-2-ylidene)-pyrrolidinium bromide

Rendement 73.0%

Solvants

sodium bicarbonate

toluene

ethyl acetate

Conditions de réaction

Traitement

1. 1
   AutrePhases were separated
2. 2
   Autrethe organic phase was transferred to a new flask
3. 3
   workup.ADDITIONtoluene (1 L) was added
4. 4
   workup.DISTILLATIONThe solution was distilled under reduced pressure to a volume of about 500 mL
5. 5
   workup.ADDITIONAn additional 500 mL of toluene was added
6. 6
   workup.DISTILLATIONdistilled under reduced pressure to a volume of about 300 mL
7. 7
   TempératureThe reaction was heated to 150° C. under Dean-Stark conditions
8. 8
   Autreabout 13 mL of water was collected
9. 9
   TempératureThe toluene solution of pyrrolidine enamine was cooled to 90° C.
10. 10
    workup.WAITAfter 30 min
11. 11
    Températureheating
12. 12
    workup.WAITwas continued at 90° C. for 2 h
13. 13
    Températureto cool to room temperature and granulate overnight
14. 14
    FiltrationThe solids were filtered
15. 15
    Lavagewashed with toluene (2×500 mL)
16. 16
    AutreAfter drying in a vacuum oven overnight (50° C.)
17. 17
    Autrethe title product of this preparation as a brown solid
18. 18
    Autrewas collected

Mode opératoire

A solution of the bisulfite adduct of bromotetralone of formula A-1 wherein Rx is Br (250 g, 760 mmol) (commercially available) in saturated sodium bicarbonate (1.25 L) and ethyl acetate (2.5 L) was stirred vigorously overnight. Phases were separated and the organic phase was transferred to a new flask and toluene (1 L) was added. The solution was distilled under reduced pressure to a volume of about 500 mL. An additional 500 mL of toluene was added and distilled under reduced pressure to a volume of about 300 mL. The solution was cooled to room temperature and pyrrolidine (54.1 g, 760 mmol) was added. The reaction was heated to 150° C. under Dean-Stark conditions. After 2 hr, about 13 mL of water was collected and concentration of a small sample showed the reaction was complete by NMR. The toluene solution of pyrrolidine enamine was cooled to 90° C. and benzyl bromide (105 mL, 912 mmol) was added dropwise. After 30 min, solids began to granulate and the solution became very thick. An additional 500 mL of toluene was added to aid stirring and heating was continued at 90° C. for 2 h. The slurry was allowed to cool to room temperature and granulate overnight. The solids were filtered and washed with toluene (2×500 mL). After drying in a vacuum oven overnight (50° C.), the title product of this preparation as a brown solid was collected: 250 g (557 mmol), 73% yield; mp 203-205° C.; IR (film) ν 1654, 1596 cm−1; 1H NMR (CDCl3) δ 7.25 (s, 1H), 7.17-7.13 (m, 3H), 7.08 (dd, 1H, J=8.3, 1.7 Hz), 6.98-6.93 (m, 2H), 6.68 (d, 1H, J=8.3 Hz), 4.29 (dd, 1H, J=7.5, 7.5 Hz), 4.25-4.17 (m, 2H), 3.95-3.86 (m, 1H), 3.62-3.49 (m, 2H), 3.27 (dd, 1H, J=13.7, 6.6 Hz), 3.14-3.05 (m, 3H), 2.07-1.95 (m, 3H), 1.92-1.84 (m, 1H); 13C NMR (CDCl3) δ 189.2, 137.2, 136.1, 132.2, 131.2, 130.9, 130.6, 129.8, 129.2, 127.8, 122.1, 55.1, 55.2, 51.3, 39.3, 34.0, 25.6, 24.9, 24.2; Anal. calcd for C21H22BrN: C, 56.15; H, 5.16; N, 3.12. Found: C, 55.64; H, 5.22; N, 3.22.

Source