ORGN 568 |
Asymmetric synthesis of the quaternary carbon of diazonamide A
| Gorka Peris and Edwin Vedejs. Department of Chemistry, University of Michigan, 930 North University, Ann Arbor, MI 48109-1055 |
| The natural product Diazonamide A was described in 1991 as the hemiacetal of 1; its structure was revised in 2001 to aminal 2. Our efforts towards the synthesis of the quaternary carbon of Diazonamide A (C10) have relied on the regioselective carboxylation of the enolate of an oxindole (3, aminal series, eq 1). The carboxylation of these substrates was controlled by the use of a chiral protecting group. This strategy resulted in good diastereocontrol in the installation of the quaternary carbon and allowed for diastereomer separation. The diastereopure oxindoles (4) were formally elaborated to the heterocyclic core of Diazonamide A (5). 
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