The Choice of Phosphane Reagent in Fukuyama−Mitsunobu Alkylation: Intramolecular Selectivity Between Primary and Secondary Alcohols in the Preparation of Asymmetric Tetraamine Building Blocks for Synthesis of Philanthotoxins
作者:Christian A. Olsen、Malene R. Jørgensen、Matthias Witt、Ian R. Mellor、Peter N. R. Usherwood、Jerzy W. Jaroszewski、Henrik Franzyk
DOI:10.1002/ejoc.200300186
日期:2003.9
phosphane reagent more bulky than trimethylphosphane gave a high intramolecular selectivity between primary and secondary hydroxy groups in the Fukuyama−Mitsunobu reaction. Thus, trimethylphosphane proved to be the only phosphane reagent that enabled alkylation of 2-nitrobenzenesulfonamides with a wide range of secondaryalcohols, whereas tributylphosphane was selective for primaryalcohol groups. This
The present invention features rifamycin analogs that can be used as therapeutics for treating or preventing a variety of microbial infections. In one form, the analogs are acetylated at the 25-position, as is rifamycin. In another form, the analogs are deacetylated at the 25-position. In yet other forms, benzoxazinorifamycin, benzthiazinorifamycin, and benzdiazinorifamycin analogs are derivatized at various positions of the benzene ring, including 3′-hydroxy analogs, and/or various fused ring systems with the benzene ring at the 4′,5′ or 5′,6′ positions.
.alpha.-Oximino amide trianions in the stereoselective synthesis of isoxazolines and .gamma.-hydroxy .alpha.-amino acids
作者:Anthony G. M. Barrett、Dashyant Dhanak、Suzanne A. Lebold、Mark A. Russell
DOI:10.1021/jo00005a042
日期:1991.3
The trianions 17 and 33, which were prepared from the corresponding alpha-oximino amides 7 and 30, were reacted with 4-methoxybenzaldehyde to stereoselectively provide, on acidification, the corresponding trans-substituted isoxazoline-3-carboxamides 8 and 31/32, respectively. Additionally, the dianion 24, which was prepared from the corresponding O-silyl oxime 22, was reacted with 4-methoxybenzaldehyde to stereoselectively give the anti beta-hydroxy oxime 23. Reduction of 8 and 26 stereoselectively gave the 2,3-syn-3,4-anti amino amides 11 and 27. Amides 11 and 27 were subsequently converted to the gamma-hydroxy-alpha-amino acids 12 and 29 and the corresponding lactones 13 and 28. Amino acid 29 is the N-terminal amino acid of the antifungal agent nikkomycin B.
Synthesis of 2′,3′-dihydrosolanesyl analogues of β-d-arabinofuranosyl-1-monophosphoryldecaprenol with promising antimycobacterial activity
Two new hydrolytically stable analogues of beta-D-arabinofuranosyl-1-monophosphoryldecaprenol, the donor substrate for mycobacterial arabinosyltransferase, have been prepared. Biological evaluation of these compounds in vitro against Mycobacterium tuberculosis H(37)Rv strain revealed a promising activity. (c) 2006 Elsevier Ltd. All rights reserved.
Palladium-catalyzed bis-coupling of dihaloaromatics with 2-amidoacrylates