Highly Efficient One-Pot Synthesis of Metalloporphyrazines under Mild Conditions

Abstract

A novel single-step preparation of free-base and metalloporphyrazines from maleonitriles was accomplished for the first time by treatment with metal salts, hexamethyldisilazane (HMDS) and p-toluene sulfonic acid (PTSA) in DMF at 120 °C. This reaction provides a new preparative method under mild conditions for direct synthesis of metalloporphyrazines having a variety of metals and substituted maleonitriles.

Key words

macrocycles - porphyrazines - maleonitrile - template - hexamethyldisilazane

References and Notes

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13

Representative Procedure.
Bis(dimethylamino)maleonitrile (328 mg, 2 mmol), HMDS (1.68 mL, 8 mmol), Zn(OAc)₂ (220 mg, 1 mmol), PTSA (38 mg, 0.2 mmol) and DMF (1 mL) were taken in a sealed tube. The reaction mixture was heated at 120 °C for 24 h under Ar atmosphere. The reaction mixture was then evaporated to dryness under reduced pressure. The resultant solid material was subjected to neutral alumina column and eluted with hexane-EtOAc (9:1). The front running blue color band was collected and evaporated to dryness under reduced pressure to get Zn-porphyrazine 2b (160 mg) in 43%. Anal. Calcd: C, 53.22; H, 6.70; N, 31.03. Found: C, 53.70; H, 6.65; N, 31.30. UV/Vis (CH₂Cl₂): λ_max (log e) = 630 (4.27), 545 (sh), 330 (4.72) nm. ¹H NMR (CDCl₃): δ = 3.70 (s) ppm. ¹³C NMR (CDCl₃): δ = 43.8, 137.7, 150.7 ppm. MS (MALDI-TOF): m/z = 722. All the compounds obtained are known and in agreement with the reported spectral and analytical data.