Structural Probing of Ketone Catalysts for Asymmetric Epoxidation
摘要:
A series of chiral ketones derived from carbohydrates were investigated as catalysts for the asymmetric epoxidation. Fructose-derived ketones are found to be efficient catalysts. The studies show that the structural requirements for the ketone catalysts are very stringent and different types of olefins may require ketones with different structural arrangements. The current study allows us to further understand the chiral ketone catalyzed asymmetric epoxidation and provides some insight for the development of new catalysts.
AMPHOTERICIN B DERIVATIVES WITH IMPROVED THERAPEUTIC INDEX
申请人:THE BOARD OF TRUSTEES OF THE UNIVERSITY OF ILLINOIS
公开号:US20160215012A1
公开(公告)日:2016-07-28
Provided are certain derivatives of amphotericin B (AmB) characterized by reduced toxicity and retained anti-fungal activity. Certain of the derivatives are C16 urea derivatives of AmB. Certain of the derivatives are C3, C5, C8, C9, C11, C13, or C15 deoxy derivatives of AmB. Certain of the derivatives include C3′ or C4′ modifications of the mycosamine appendage of AmB. Also provided are methods of making AmB derivatives of the invention, pharmaceutical compositions comprising AmB derivatives of the invention, and methods of use of AmB derivatives of the invention.
Modular Monodentate Oxaphospholane Ligands: Utility in Highly Efficient and Enantioselective 1,4-Diboration of 1,3-Dienes
作者:Christopher H. Schuster、Bo Li、James P. Morken
DOI:10.1002/anie.201102404
日期:2011.8.16
Tune it up! Tunable, chiral, monodentateoxaphospholaneligands (termed OxaPhos) are highly effective in the Pt‐catalyzed title reaction, providing the 1,4‐addition products in enantiomer ratios approaching 99:1 (see scheme). In the presence of enantiomerically pure cis‐iBu‐OxaPhos, a catalyst loading of only 0.02 mol % [Pt(dba)3] was sufficient for effective reaction. pin=pinacolato, dba=dibenzylideneacetone
2,3-<i>O</i>-(3-Pentylidene)-D-glyceraldehyde and 2,3-<i>O</i>-(3-Pentylidene)-L-glyceraldehyde: Convenient Glyceraldehyde Surrogates Obtained via a Novel Periodate-Based Oxdation System
作者:Christopher R. Schmid、David A. Bradley
DOI:10.1055/s-1992-26170
日期:——
The synthesis of two novel glyceraldehyde surrogates, 2,3-O-(3-pentylidene)-D-glyceraldehyde (2) and 2,3-O-(3-pentylidene)-L.-glyceraldehyde (3) is presented. Synthesis, handling and storage advantages of 2 and 3 over the conventionally employed 2,3-O-isopropylidene-D-glyceraldehyde (1) are discussed. The 3-pentanone-derived protecting group facilitates the extraction of product from aqueous oxidation solutions, while the 3-pentanone liberated on ketal deprotection can be efficiently removed at reduced pressures. The synthesis employs a buffered potassium periodate oxidation which offers significant advantages over sodium periodate in glycol cleavage reactions.
Spongistatin Synthetic Studies. An Efficient, Second-Generation Construction of an Advanced ABCD Intermediate
作者:Amos B. Smith、Victoria A. Doughty、Chris Sfouggatakis、Clay S. Bennett、Jyunichi Koyanagi、Makoto Takeuchi
DOI:10.1021/ol017273z
日期:2002.3.1
short, efficient, and stereocontrolled synthesis of (-)-4, an advanced ABCD subunit of the spongistatins, has been achieved. Central to the synthetic strategy is the multicomponent linchpin union of silyl dithianes with epoxides to access both the AB and CD fragments. Fragment coupling was then achieved via an efficient stereoselective aldol reaction. The linear sequence required 22 steps and proceeded