21H,22H-Porphine → HCID 178419803, compound

Participants

Reaction Steps

Synthesis. A sample of 4-bromobenzaldehyde dimethylacetal46 was coupled with di-tert-butylphosphite to give 4-(di-tert-butyloxyphosphoryl)benzaldehyde dimethylacetal. The latter was used in a mixed-aldehyde condensation47 with pyrrole under standard conditions of BF3.O(Et)2-ethanol cocatalysis48 followed by oxidation with DDQ to give porphyrin 1. Porphyrin 1 was metalated with Zn(OAc)2.2H2O in CHCl3/methanol to afford zinc porphyrin Zn1 in 73% yield (Scheme 1). Cleavage of the tert-butyl groups was achieved by following the known procedure45 with TMS-Cl/TEA in refluxing CHCl3 (stabilized with amylenes). In this manner, the porphyrin Zn2 was obtained without demetalation in 89% yield. Note that CHCl3 stabilized with amylenes rather than ethanol was used to avoid the possible reaction of ethanol with TMS-Cl.

Provenance & Evidence