Favourable involvement of α2A-adrenoreceptor antagonism in the I2-imidazoline binding sites-mediated morphine analgesia enhancement
摘要:
Aim of the present study was to obtain novel alpha(2)-adrenoreceptor (alpha(2)-AR) antagonists, possibly endowed with subtype-selectivity. Therefore, inspired by the non subtype-selective alpha(2)-AR antagonist idazoxan, we designed 1,4-dioxane derivatives bearing an aromatic area in position 5 or 6 and the imidazoline nucleus in position 2. Among the novel molecules 1-6, compound 2, with a trans stereochemical relationship between 5-phenyl and 2-imidazoline groups, was able to antagonize the sole alpha(2A)-subtype. Moreover, 2 showed an affinity at I-2-imidazoline binding sites (I-2-IBS) comparable to that at alpha(2A)-AR. In in vivo studies 2 strongly increased morphine analgesia. This interesting behaviour appeared to be induced by the favourable involvement of alpha(2A)-AR antagonism in the I-2-IBS-mediated morphine analgesia enhancement. (C) 2012 Elsevier Ltd. All rights reserved.
Alternative Sm(II) Species-Mediated Cascade Coupling/Cyclization for the Synthesis of Oxobicyclo[3.1.0]hexane-1-ols
摘要:
The allylSmBr/HMPA/MsOH system has been found to be an efficient reagent for the "ester-alkene" coupling/cyclization cascade of readily available a-allyloxy esters. Oxobicyclo[3.1.0]hexane-1-ols were thus prepared in good to excellent yields and diastereoselectivities. Investigation on the mechanism suggested the possible existence of a new Sm(II) species, namely, CH3SO3SmBr, which resulted from the reaction between allylSmBr and MsOH and may be the actual SET reagent.
Enantioselective C−C Bond Formation by Rhodium-Catalyzed Tandem Ylide Formation/[2,3]-Sigmatropic Rearrangement between Donor/Acceptor Carbenoids and Allylic Alcohols
作者:Zhanjie Li、Huw M. L. Davies
DOI:10.1021/ja9075293
日期:2010.1.13
The rhodium-catalyzed reaction of racemic allyl alcohols with methyl phenyldiazoacetate or methyl styryldiazoacetate results in a two-step process, an initial oxonium ylide formation followed by a [2,3]-sigmatropic rearrangement. This process competes favorably with the more conventional O-H insertion chemistry as long as donor/acceptor carbenoids and highly substituted allyl alcohols are used as substrates
environmentally benign character of iron mean that it is an ideal alternative to precious metals in catalysis. Recent growth in the number of iron-catalysed reactions reported reflects an increasing demand for sustainable chemistry. Only a limited number of chiral iron catalysts have been reported and these have, in general, proven less enantioselective than other transition-metal catalysts, thus limiting their