Doris P. Schumacher

A copper-free palladium catalyzed cross coupling reaction of vinyl tosylates with terminal acetylenes

A copper-free palladium-catalyzed cross coupling of vinyl tosylate (2) and terminal acetylenes was investigated, affording a convenient and efficient method for construction of an sp–sp2 carboncarbon bond. The tosylate (2) derived from 1,3-cyclohexanedione was reacted with terminal acetylene under the copper-free conditions at ambient temperature, in the presence of palladium acetate and triphenylphosphine, to provide the conjugated en-yn-one products in excellent overall yields while leaving other functional groups intact. This reaction protocol was extended to coumarin tosylate (12).

Preparations of antifungal Sch 42427/SM 9164: Preparative chromatographic resolution, and total asymmetric synthesis via enzymatic preparation of chiral α-hydroxy arylketones

Abstract Efficient approaches towards the preparation of chiral azole antifungals Sch 42427/SM 9164 (1) via large scale chromatographic separation of its enantiomers, or via enzymatic syntheses of key chiral intermediates α-hydroxy arylketones 5 in excellent enantiomeric excesses (ees) are described.

Reaction of aziridinium ions with organometallic reagents: optimization of the key step of ecopipam synthesis

Formation, stability and reactivity of aziridinium ions 3 towards organometallic reagents was explored and optimized for the efficient preparation of key drug intermediate 5c.

SCH 23831, a novel macrolide from Micromonospora rosaria

Abstract A novel macrolid elaborated by Micromonospora rosaria , SCH 23831, was assigned structure 2 on the basis of spectroscopic data. Several derivatives are also discussed.

The synthesis of netilmicin via complexing of vicinal and non-vicinal amino-hydroxyl group pairs with divalent transition-metal cations

Sisomicin was converted into 3,2′,6′-tri-N-acetylsisomicin by acetylation of its 3″,4″-vicinal-cis and 1,2″-non-vicinal amino-hydroxyl group pair complex of copper(II) or cobalt(II) acetate. The tri-N-blocked derivative was reductively monoalkylated at the 1-position with acetaldehyde and sodium cyanoborohydride and then N-deprotected to give netilmicin.

Structure elucidation of Sch 49088, a novel everninomicin antibiotic containing an unusual hydroxylamino-ether sugar, everhydroxylaminose

Abstract Degradation of Sch 49088 ( 1 ) provided a novel, highly functionalized O-substituted hydroxylamine-containing sugar, everhydroxylaminose 11 isolated as a β-OMe glycoside. Notably the two acid sensitive orthoester moieties in the intact antibiotic 1 co-exist in the presence of three phenolic groups and a free carboxylic acid group.