... compounds 7a-d were first oxidated with m-chloroperbenzoic acid (MCP- BA) and then submitted to regiospecific substitution with heterocyclic bases. ... Journal of Medicinal Chemistry, 1993, Vol. ... 4.21 (2 H, q, J = 6 Hz, CHzCHs), 4.50-4.70 (2 H, m, NCHZ), 8.18 (1 H, d, J = 9 Hz, H ...