Harukazu Fukami

Revisit to the sulfonation of pyrroles: is the sulfonation position correct?

Abstract Sulfonation of pyrrole and its 1-methyl derivatives with a sulfur trioxide–pyridine complex was found to give 3-sulfonated pyrroles, but not 2-sulfonates as described in textbooks. The replacement of 1-methyl-2-tri- n -butylstannylpyrrole with trimethylsilyl chlorosulfonate, followed by quenching with aq. NaHCO 3 also generated sodium 1-methylpyrrole-3-sulfonate, not 2-sulfonate.

Background and features of emil, a system for database-aided bioanalogous structural transformation of bioactive compounds

Abstract Various structural transformation processes observed in a number of past developmental examples of pharmaceuticals and agrochemicals are regarded as being invaluable precedents for the prospective analog design. In certain cases, (sub)structural transformation patterns are interchangeable among various compound series in spite of differences in their pharmacological category. Thus, the patterns extracted with a computer-readable format could be accumulated and integrated as a database for potential “rules” for bioanalogous molecular transformations. EMIL is a system that incorporates the database and a data-processing engine constructed to release “higher-ordered” candidate structures from a “lower-ordered” input structure “automatically”. Conceptual background for the database construction and the procedure for the database collection are presented on the basis of some lead evolution examples among pharmaceutical and agrochemical series of compounds.

Syntheses of Ribofuranosyl-2-deoxystreptamines

4-0-, 5-0- and 6-0-β-d-Ribofuranosyl-2-deoxystreptamine derivatives were prepared from 4 (or 6)-O-acetyl-N, N′-dicarbobenzyloxy-2-deoxystreptamine and 2, 3, 5-tri-O-benzoyl-d-ribofuranosyl chloride by a modified Konigs-Knorr reaction. Structures were determined by identification with an authentic sample derived from neomycin for the 5-O-isomer, and by comparison of the Δ [M]CuAm values of their N-acetyl derivatives for the 4-0- and 6-O-isomers.

Total Synthesis of Ribostamycin

Suitably protected 5-O-β-d-ribofuranosyl-2-deoxystreptamine was condensed with protected 2, 6-diamino-2, 6-dideoxy-a-d-glucopyranosyl bromide by a modified Konigs-Knorr reaction to give three condensation products. One of which was confirmed as a ribostamycin derivative. The others were designated as its 6-O-α- and 6-O-β-isomers by the PMR spectra of their free bases and N-acetyl derivatives and by their chemical reactions.