Reaction #164002

Reaction equation

methanol

{8-[1-Cyano-4-(1,3-dimethyl-2,4,6-trioxo-tetrahydro-pyrimidin-5-ylidene)-but-2-enylidene]-10,10-dimethyl-8,10-dihydro-pyrido[1,2-a]indol-2-ylmethyl}-carbamic acid tert-butyl ester

iodotrimethylsilane

iodotrimethylsilane

→

8-[1-Cyano-4-(1,3-dimethyl-2,4,6-trioxo-tetrahydro-pyrimidin-5-ylidene)-but-2-enylidene]-10,10-dimethyl-8,10-dihydro-pyrido[1,2-a]indol-2-ylmethyl-ammonium iodide

Solvents

acetonitrile

Conditions

Workup

1. 1
   Otherequipped with magnetic stir bar
2. 2
   OtherThe flask was closed with rubber septa
3. 3
   Otherreaction mixture
4. 4
   OtherThe volume of reaction mixture
5. 5
   Otherwas reduced in about half using rotary evaporator
6. 6
   OtherDuring this operation most of the methanol was removed from the reaction mixture
7. 7
   Otherprecipitates
8. 8
   FiltrationThe product was filtered
9. 9
   Washwashed with acetonitrile
10. 10
    Otherdried
11. 11
    Othertransferred to a 500-mL conical flask
12. 12
    Otherequipped with magnetic stirrer
13. 13
    workup.ADDITION200 mL of dichloromethane were added to the flask, and flask content
14. 14
    workup.STIRRINGwas stirred
15. 15
    Temperaturewith mild heating (very gentle DCM boiling) for 10 min
16. 16
    FiltrationThe mixture was filtered when still hot
17. 17
    Washthe dye was washed with DCM
18. 18
    Otherdried

Procedure

{8-[1-Cyano-4-(1,3-dimethyl-2,4,6-trioxo-tetrahydro-pyrimidin-5-ylidene)-but-2-enylidene]-10,10-dimethyl-8,10-dihydro-pyrido[1,2-a]indol-2-ylmethyl}-carbamic acid tert-butyl ester (20 g, 0.04 mol; Sigma-Aldrich) from previous step was placed in one-necked round bottom 1 L flask equipped with magnetic stir bar and dissolved in 150 mL of acetonitrile. The flask was closed with rubber septa and flashed with dry nitrogen. 10 g of iodotrimethylsilane were added to the flask with use of syringe, and reaction mixture was stirred at room temperature for 30 min. During addition of iodotrimethylsilane the color of the flask changed from deep blue to deep orange. 25 mL of methanol were added to the reaction mixture and its color become deep blue again. The volume of reaction mixture was reduced in about half using rotary evaporator. During this operation most of the methanol was removed from the reaction mixture and the product, which is insoluble in acetonitrile, precipitates. The product was filtered, washed with acetonitrile, dried and transferred to a 500-mL conical flask equipped with magnetic stirrer. 200 mL of dichloromethane were added to the flask, and flask content was stirred with mild heating (very gentle DCM boiling) for 10 min. The mixture was filtered when still hot, the dye was washed with DCM and dried. The yield was 10 g (50% of theory based on two steps).

Source