Diethyl Ether → HCID 178435499, compound

HRID 1729008Notes

Reaction equation

HRID 1729008 reaction equation
[CH3:1][CH2:2][C:3]1[C:21]2=[N:22][C:5](=[CH:6][C:7]3[NH:11][C:10]([CH:12]=[C:13]4[CH:34]([CH3:35])[CH:33]([CH2:36][CH2:37][C:38]([O:40][CH3:41])=[O:39])[C:15]([C:16]5C(C(OC)=O)[C:25](=[O:26])[C:24]6[C:17]=5[NH:18][C:19]([C:23]=6[CH3:32])=[CH:20]2)=[N:14]4)=[C:9]([CH3:42])[C:8]=3[CH:43]=[CH2:44])[C:4]=1[CH3:45].[OH-:46].[K+].C[CH2:49][O:50]CC>N1C=CC=CC=1.C(O)CC>[CH3:1][CH2:2][C:3]1[C:21]2[NH:22][C:5](=[CH:6][C:7]3[NH:11][C:10]([CH:12]=[C:13]4[NH:14][C:15]([C:16]5[C:49](=[O:50])[O:26][C:25](=[O:46])[C:24]6=[C:23]([CH3:32])[C:19]([CH:20]=2)=[N:18][C:17]=56)=[C:33]([CH2:36][CH2:37][C:38]([O:40][CH3:41])=[O:39])[C@@H:34]4[CH3:35])=[C:9]([CH3:42])[C:8]=3[CH:43]=[CH2:44])[C:4]=1[CH3:45]

Participants

6

Reactant 3

HCID 3283Diethyl EtherHCID 14797Potassium HydroxideHCID 178435494HCID 178435494, compound

Product 1

HCID 178435499HCID 178435499, compoundYield 50%

Reagents, catalysts & solvents 2

HCID 10311-PropanolSolventHCID 1049PyridineSolvent

Procedure

Methyl pheophorbide-a (2) prepared in Example 1 (300 mg, 0.49 mmole) was dissolved in warm pyridine (5 mL) and the solution was diluted with ether (500 mL). The solution was stirred with a stream of air passing through it, and a solution of potassium hydroxide (4 g) in n-propanol (10 mL) was added. The bright green mixture containing precipitated potassium hydroxide was stirred and aerated for 30 min and then extracted with wateruntil the ethereal layer was no longer green. The ethereal solution was discarded, the aqueous extracts were combined and adjusted to pH~4 with concentrated sulfuric acid (~4 mL). Then the mixture was extracted with methylene chloride until the aqueous layer was no longer green-brown. The combined methylene chloride extract containing so-called "unstable chlorin" was subjected to repeated evaporation and redissolutionin distilled THF until no further increase in visible absorption at 700 nm was observed. The product was esterified with ethereal diazomethane, then washed with water, dried and evaporated to dryness. The product was purified on preparative TLC plates, eluting with 2% methanol in methylene chloride to give a purple-brown band. After evaporating the solvents, the residue was crystallized from methylene chloride/methanol to yield 143 mg (50%) of purpurin-18 methyl ester (3).

Workup

  1. additionThe bright green mixture containing
  2. customprecipitated potassium hydroxide
  3. stirringwas stirred
  4. extractionextracted with wateruntil the ethereal layer
  5. extractionThen the mixture was extracted with methylene chloride until the aqueous layer
  6. extractionThe combined methylene chloride extract
  7. additioncontaining so-called "unstable chlorin"
  8. customevaporation and redissolutionin
  9. distillationdistilled THF until
  10. temperatureno further increase in visible absorption at 700 nm
  11. washwashed with water
  12. customdried
  13. customevaporated to dryness
  14. customThe product was purified on preparative TLC plates
  15. washeluting with 2% methanol in methylene chloride
  16. customto give a purple-brown band
  17. customAfter evaporating the solvents
  18. customthe residue was crystallized from methylene chloride/methanol

Sources & evidence

ORD record
ord-9b61f45a4f8648a583bca911e39098f2
Source dataset
uspto-grants-1994_07
Patent number
US05330741

Reaction notes

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