Boron-complexation strategy for use with 1-acyldipyrromethanes.
1-Acyldipyrromethanes are important precursors in rational syntheses of diverse porphyrinic compounds. 1-Acyldipyrromethanes are difficult to purify, typically streaking upon chromatography and giving amorphous powders upon attempted crystallization. A solution to this problem has been achieved by reacting the 1-acyldipyrromethane with a dialkylboron triflate (e.g., Bu2B-OTf or 9-BBN-OTf) to give the corresponding B,B-dialkyl-B-(1-acyldipyrromethane)boron(III) complex. The reaction is selective for a 1-acyldipyrromethane in the presence of a dipyrromethane. The 1-acyldipyrromethane-boron complexes are stable to routine handling, are soluble in common organic solvents, are hydrophobic, crystallize readily, and chromatograph without streaking. The 1-acyldipyrromethane can be liberated in high yield from the boron complex upon treatment with 1-pentanol. Alternatively, the 1-acyldipyrromethane-boron complex can be used in the formation of a trans-A2B2-porphyrin. In summary, the boron-complexation strategy has broad scope and greatly facilitates the isolation of 1-acyldipyrromethanes.
Muthukumaran
Kannan
K
Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA.
Ptaszek
Marcin
M
Noll
Bruce
B
Scheidt
W Robert
WR
Lindsey
Jonathan S
JS
D000215:Acylation; D001895:Boron / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D007202:Indicators and Reagents; D008697:Methane / Q000737:chemistry*; D015394:Molecular Structure; D011166:Porphyrins / Q000138:chemical synthesis*; D011758:Pyrroles / Q000138:chemical synthesis* / Q000737:chemistry
D007202:Indicators and Reagents; D011166:Porphyrins; D011758:Pyrroles; D001895:Boron; D008697:Methane