Probing chemical space with alkaloid-inspired libraries
作者:Michael C. McLeod、Gurpreet Singh、James N. Plampin、Digamber Rane、Jenna L. Wang、Victor W. Day、Jeffrey Aubé
DOI:10.1038/nchem.1844
日期:2014.2
Screening of small-moleculelibraries is an important aspect of probe and drug discovery science. Numerous authors have suggested that bioactive natural products are attractive starting points for such libraries because of their structural complexity and sp3-rich character. Here, we describe the construction of a screening library based on representative members of four families of biologically active
An efficient first approach to the Stemona alkaloid (+/-)-Stemonamine has been developed on the basis of a key TiCl4 promoted tandem Semipinacol rearrangement/Schmidt reaction and a Dieckmann condensation reaction.
Domino Reactions That Combine an Azido-Schmidt Ring Expansion with the Diels−Alder Reaction
The combination of the intramolecular Schmidt reaction with the Diels-Alder reaction provides expedient access to a variety of heterocycles. Two different modes of reaction planning are presented. In one, the azide and ketone moieties necessary for the intramolecular Schmidt reaction originate on different molecules that are reacted and subsequently undergo a ring-adjustment step. Alternatively, an azido ketone can be used provided the ketone is deactivated by its presence in an enone.
Intramolecular Schmidt Reactions of Alkyl Azides with Ketones: Scope and Stereochemical Studies
作者:Gregory L. Milligan、Craig J. Mossman、Jeffrey Aube
DOI:10.1021/ja00147a006
日期:1995.10
The intramolecular Schmidt reaction of alkyl azides and ketones has been demonstrated. The reaction is proposed to occur via initial attack of an azide on a ketone activated by a variety of protic or Lewis acids, including trifluoroacetic acid, titanium tetrachloride, and others. The resulting azidohydrin undergoes a direct rearrangement to afford the product amide and molecular nitrogen. When cyclic ketones are used, fused bicyclic lactams of types encountered in a wide variety of natural products are obtained. Although the distance allowed between the carbonyl group and the alkyl azide is quite restricted, the reaction is general with respect to the ketone component, including acyclic ketones and cyclic substrates ranging from standard to large ring sizes. The reaction also succeeds with aldehydes, although elimination or hydride migration products compete. In several cases examined, the reaction was found to proceed with retention of configuration at the migrating carbon. Competing reactions with beta-diketones and alpha,beta-unsaturated ketones were found to predominate over ring expansion.
Thermal rearrangements of α-(ω-azidoalkyl) enones
作者:Gary A. Molander、Christopher T. Bibeau
DOI:10.1016/s0040-4039(02)01077-8
日期:2002.7
The thermal rearrangement of alpha-(omega-azidoalkyl) enones has been investigated. A variety of these substrates were synthesized and subjected to thermal rearrangement to investigate the scope and generality of their transformation to bicyclic lactams. (C) 2002 Elsevier Science Ltd. All rights reserved.