Isoquinoline quinones

This quinone synthesis was used to obtain the isoquinoline quinone 2, a unit of some saframycin antibiotics (equation I). 

Milanowski DJ, Gustafson KR, Kelley JA, McMahon JB (2004) Caulibugulones A-F, Novel Cytotoxic Isoquinoline Quinones and Iminoquinones from the Marine Bryozoan Caulibugula intermis. J Nat Prod 67 70... 

Diels-Alder addition of azadienes to quinones has been used to prepare analogues of the antibiotic diazaquinomycin (26). Quinoline-5,6-quinone yields both regioisomers (Equation (8)) while the isoquinoline quinone gives only the pyrido[3,4- ]quinoline (79) (Equation (9)) <91TL1307>. 

Most of the isoquinoline quinones described above have antibacterial activity (Table 3) and moderate levels of cytotoxicity (Table 1) have been reported. Other bioactivity reported for mimosamycin and 7-amino-7-demethoxymimosamycin (89) are aldose reductase inhibition, 34.6% at 10 pmol dm 3, and cAMP phosphodiesterase inhibition, 26.3% at 100 pmol dm 3, respectively (71). 

Fig. (6). Isolated isoquinoline quinone alkaloids from Xestospongia sp.

Pyridine is present in many metabolites of haplosderid sponges, but few examples have been found in Halichon-drida, such as pyraxinine (pyridylguanidine), isolated from Cymbastela cantharella from New Caledonia (Al Mourabit et al, 1997) and related to girolline (Al Mourabit and Potier, 2001). Mimosamydn, an isoquinoline quinone of bacterial origin (Streptomyces lavandulae), has been isolated... 

Parker, K.A. and Casteel, D.A. (1988) Isoquinoline quinones. Preparation of saframydn intermediates and a total synthesis of mimosamycin. J. Org. Chem., 53, 2847-2850. 

MilanovskL D.J., Gustafson, K.R., Kelley, J.A., and McMahon, J.B. (2004) Cauhhugulones A-F, novel cytotoxic isoquinolines quinones and iminoquinones from the marine bryozoan Caulibugula intermis. J. Nat. Prod., 67, 70-73. 

Park, A. and Schmitz, F.J. (1993) Synthesis of perfragilin B, a cytotoxic isoquinoline quinone isolated from the bryozoan Membranipora peifragilis. Tetrahedron Lett., 34, 3983-3984. 

---