Carbacephems have been synthesized from D-serine by two routes involving construction first of the six-membered ring followed by cyclization to give the bicyclic beta-lactam. In one route, alkylation of a lactim ether was accomplished with Ni(Acac)(2) as a catalyst. The desired R stereochemistry at the carbon corresponding to C-6 of the cephem was obtained by stereospecific hydrogenation of a vinylogous carbamate. The second route involved a stereospecific Michael cyclization to give the same C-6 stereochemistry. Closure of a piperidyl beta-amino acid intermediate common to both routes was accomplished using a modified Mukaiyama reagent found to be superior in our system to the traditional reagent. The resulting carbacephem core was stereospecifically substituted at C-7 with an ethyl or amino functionality. The ethylated intermediate was transformed into a stable enol triflate useful for the further elaboration of biologically important carbacephems.
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.
作者:Wanjin Zhong、Chuan Wan、Ziyuan Zhou、Chuan Dai、Yichi Zhang、Fei Lu、Feng Yin、Zigang Li
DOI:10.1021/acs.orglett.3c03539
日期:2023.12.8
Through systematic optimization of halopyridinium compounds, we established a peptide coupling protocol utilizing 4-iodine N-methylpyridinium (4IMP) for solid-phase peptidesynthesis (SPPS). The 4IMP coupling reagent is easily prepared, bench stable, and cost-effective. Employing 4IMP in the SPPS process has showcased remarkable chemoselectivity and efficiency, effectively eliminating racemization
Silver halide light sensitive emulsion layer having enhanced photographic sensitivity
申请人:EASTMAN KODAK COMPANY
公开号:EP0786692A1
公开(公告)日:1997-07-30
A photographic element comprises at least one silver halide emulsion layer in which the silver halide is sensitized with a compound of formula
Z-(L-XY)k
wherein:
Z is a light absorbing group;
L is a linking group containing a least one
C, N, S, or O atom; and
k is 1 or 2; and
XY represents a fragmentable electron donor moiety wherein:
1) XY has a an oxidation potential between 0 and about 1.4 V;
2) X is an electron donor group;
3) Y is a leaving group other than hydrogen; and
4) the oxidized form of XY undergoes a bond cleavage reaction to give the radical X• and the leaving fragment Y.
In a preferred embodiment the radical X• has an oxidation potential of ≤ -0.7 V.
感光元件包括至少一个卤化银乳剂层,其中的卤化银是用式 1 的化合物感光的。
Z-(L-XY)k
其中
Z 是光吸收基团
L 是连接基团,含有至少一个
C、N、S 或 O 原子的连接基团;以及
k 是 1 或 2;以及
XY 代表可碎裂的电子供体分子,其中
1) XY 的氧化电位在 0 至约 1.4 V 之间;
2) X 是电子供体基团
3) Y 是氢以外的离去基团;以及
4) XY 的氧化形式发生键裂反应,生成自由基 X- 和离去片段 Y。
在一个优选的实施方案中,自由基 X- 的氧化电位≤ -0.7 V。
Amphotericin B derivatives with improved therapeutic index
申请人:The Board of Trustees of the University of Illinois
公开号:US10323057B2
公开(公告)日:2019-06-18
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.
本文提供了两性霉素 B(AmB)的某些衍生物,其特点是毒性降低,抗真菌活性保持不变。其中某些衍生物是 AmB 的 C16 脲衍生物。某些衍生物是 AmB 的 C3、C5、C8、C9、C11、C13 或 C15 脱氧核衍生物。某些衍生物包括 AmB 的霉菌胺附属物的 C3′或 C4′修饰。此外,还提供了制造本发明AmB衍生物的方法、包含本发明AmB衍生物的药物组合物以及本发明AmB衍生物的使用方法。
ORGANOCATALYTIC ENANTIOSELECTIVE SYNTHESIS OF BICYCLIC ß-LACTONES VIA NUCLEOPHILE-CATALYZED ALDOL-LACTONIZATION (NCAL)
作者:Nguyen, Henry、Oh, Seongho、Henry-Riyad, Huda、Sepulveda, Diana、Romo, Daniel