Structural requirements of dictyopyrones isolated from Dictyostelium spp. in the regulation of Dictyostelium development and in anti-leukemic activity
摘要:
Cellular slime molds are fascinating to the field of developmental biology, and have long been used as excellent model organisms for the study of various aspects of multicellular development. We have recently isolated alpha-pyronoids, named dictyopyrones A-D (1-4), from various species of Dictyostelium cellular slime molds, and it was shown that compound 3 may regulate Dictyostelium development. In this study, we synthesized dictyopyrones A-D (1-4) and their analogues, investigated the physiological role of the molecules in cell growth and morphogenesis in D. discoideum, and further verified their effects on human leukemia K562 cells. Nitrogen-containing compounds 22 and 37 strongly inhibited cell growth in K562 leukemia cells, indicating that these compounds may be utilized as novel lead compounds for anti-leukemic agents. (C) 2004 Elsevier Ltd. All rights reserved.
Triethyl- (or Trimethyl-)Silyl Triflate-Catalyzed Reductive Cleavage of Triphenylmethyl (Trityl) Ethers with Triethylsilane
摘要:
[GRAPHICS]A triphenylmethyl (trityl) ether was reductively and instantaneously cleaved by triethylsilane in the presence of a catalytic amount of TES- (or TMS)-triflate. The reaction conditions are mild enough to achieve reduction in the presence of a variety of acid-sensitive functional groups. Upon a mild acidic treatment of the crude product, the corresponding alcohol is obtained in high yield.
Reductive cleavage of benzyl ethers with lithium naphthalenide. A convenient method for debenzylation
作者:Hsing-Jang Liu、Judy Yip、Kak-Shan Shia
DOI:10.1016/s0040-4039(97)00345-6
日期:1997.3
An operationally simple, high-yielding and highly chemoselective procedure has been developed for the conversion of benzyl ethers to the corresponding alcohols, using lithium naphthalenide as the reagent.
Herein we report the isolation and characterization of aminal intermediates in the organocatalytic α‐chlorination of aldehydes. These species are stable covalent ternary adducts of the substrate, the catalyst and the chlorinating reagent. NMR‐assisted kinetic studies and isotopic labeling experiments with the isolated intermediate did not support its involvement in downstream stereoselective processes
Deprotection of mono and dimethoxy phenyl methyl ethers using catalytic amounts of DDQ
作者:S. Chandrasekhar、G. Sumithra、J.S. Yadav
DOI:10.1016/0040-4039(96)00081-0
日期:1996.3
4-Methoxy and 3,4 dimethoxy benzyl ethers have been deprotected with catalyticamounts of DDQ by oxidative recycling of the byproduct DDHQ with FeCl3 for the first time.
Primary alcohols and primary/secondary amines are labelled with D atom at α-position regioselectively by means of deuterium oxide and ruthenium catalyst.