Synthesis of hexacyclic parnafungin A and C models.
A convergent, practical route to unstable hexacyclic parnafungin A and C models has been developed. Two iodoxanthones were prepared in four or five steps (33-50% overall yield). Suzuki-Miyaura coupling of the iodoxanthones with excess readily available 3-carbomethoxy-2-nitrophenyl pinacol boronate afforded the hindered highly functionalized 2-arylxanthones (53-58%) in the first key step. In the second key step, zinc reduction gave benzisoxazolinones that were treated with MsCl and then base to generate the unstable hexacyclic parnafungin A (13% overall yield for 8 steps) and C (8% overall yield for 9 steps) models. Analogously to the parnafungins, hexacyclic parnafungin C model decomposes to a phenanthridine with a half-life of 2 d in CDCl(3).
Department of Chemistry, MS 015, Brandeis University, Waltham, Massachusetts 02454-9110, USA.
Quan
Q
Zhou
Barry B
BB
Snider
D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D023303:Oxazolidinones / Q000138:chemical synthesis* / Q000737:chemistry; D010617:Phenanthridines / Q000138:chemical synthesis* / Q000737:chemistry; D011083:Polycyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry
D023303:Oxazolidinones; D010617:Phenanthridines; D011083:Polycyclic Compounds; C555842:parnafungin A1; C555843:parnafungin A2; C538877:parnafungin C