Step saver: Carbonyl groups with lower reactivities can be transformed in the presence of more reactive ones by treatment with PPh3 (or PEt3) and TMSOTf prior to the reaction (see scheme; TMS=trimethylsilyl, Tf=trifluoromethanesulfonyl). This methodology can be applied to reduction and alkylation reactions, and enabled the short asymmetric totalsynthesis of (+)‐centrolobine with the highest overall
New potent inhibitors of tyrosinase: Novel clues to binding of 1,3,4-thiadiazole-2(3H)-thiones, 1,3,4-oxadiazole-2(3H)-thiones, 4-amino-1,2,4-triazole-5(4H)-thiones, and substituted hydrazides to the dicopper active site
作者:Usman Ghani、Nisar Ullah
DOI:10.1016/j.bmc.2010.04.021
日期:2010.6.1
hydrazides were tailored and synthesized as new potent inhibitors of tyrosinase. The rationale for inhibitor design was based on the active site structural evidence from the crystal structures of bacterial tyrosinase and potato catechol oxidase enzymes. Kinetic and active site binding studies suggested mono-dentate binding of thiadiazole, oxadiazole, and triazole rings to the active site dicopper center
A Mild, Efficient and Selective Cleavage of Aryl<i>tert</i>-Butyldimethysilyl Ethers Using KOH in Ethanol
作者:Zhi-Yong Jiang、Yan-Guang Wang
DOI:10.1246/cl.2003.568
日期:2003.7
An efficient and selective method for the deprotection of aryl tert-butyldimethysilyl (TBS) ethers is described. The protecting group TBS could be cleaved from aryl silyl ethers in the prensence of alkyl TBS ethers using KOH in ethanol at room temperature to give the corresponding phenols in excellent yields (87–99%).
A Facile One-Pot Transformation of Baylis-Hillman Adducts into Unsymmetrical Disubstituted Maleimide and Maleic Anhydride Frameworks: A Facile Synthesis of Himanimide A
Unsymmetrical, disubstitutedmaleimide and maleicanhydrideframeworks have been accessed from Baylis–Hillmanadducts in an operationally simple three‐step (Friedel–Crafts reaction, selective hydrolysis, and cyclization), one‐pot strategy. This strategy has been successfully extended to the synthesis of a representative bioactive compound, himanimide A (see scheme).
A mild, efficient and selective deprotection of t-butyldimethylsilyl-protected phenols using cesium carbonate
作者:Zhi-Yong Jiang、Yan-Guang Wang
DOI:10.1016/s0040-4039(03)00736-6
日期:2003.5
A mild and efficient method for the deprotection of aryl t-butyldimethysilyl (TBS) ethers is described. The protecting group TBS could be cleaved from aryl silyl ethers using cesium carbonate in DMF-H2O at room temperature to give the corresponding phenols in excellent yields. The reaction conditions allowed selective deprotection of aryl TBS-protected phenols in the presence of TBS, pbenyloxycarbonyl or tetrahydropyranyl-protected alcohols. (C) 2003 Elsevier Science Ltd. All rights reserved.