Die Aminothiazole (I) kondensieren mit den α‐Bromketonen (II) zu den Derivaten (III), die zu den Imidazothiazolen (IV) cyclisiert werden (mittel bis gute Ausbeuten an (III) und (IV)).

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A heterogeneous catalytic method for the preparation of trans-aziridines from imines and methyl diazoacetate is described using Rh III -and Mn III -exchanged montmorillonite K10 clays as catalysts.

A modular synthesis of unsaturated 1-monoacylglycerols (1) from cis-1-iodo-1-alkenes [cis-RCH=CHI] and unsaturated carboxylic acids [CH 2 =CH(CH 2 ) n CO 2 H] is described. The method revolves around a Suzuki coupling to establish olefin geometry.We needed to prepare a series of cis unsaturated 1-monoacylglycerols (1-MAG) of type 1 in connection with a project directed toward developing and understanding the in meso method for crystallization of membrane-associated proteins. 1 Standard procedures for the synthesis of 1-MAGs were used to prepare several compounds of type 1 (Figure 1) from commercially available fatty acids with the appropriate neck (N) and tail (T) length. 2,3 Not all of the fatty acids required for our studies, however, were commercially available. Thus, we developed a modular approach to the synthesis of compounds of type 1 that should be amenable to the synthesis of a wide variety of 1-MAGs. The details of this approach are described herein.The aforementioned crystallization studies dictated that we prepare 1-MAGs with at least 99% homogeneity of cis olefin geometry. It was our experience that catalytic hydrogenation of alkynes was unsatisfactory in this regard and thus, we turned to other methods that would be less capricious in regard to olefin geometry. 4 We eventually settled on an approach that revolves around the coupling of alkenes with iodoalkenes, methodology pioneered by the Suzuki group. 5 The preparation of the coupling partners for this approach is shown in Scheme 1 and Scheme 2.cis-Iodoalkenes were prepared using established procedures (Scheme 1). Terminal alkynes 2 were deprotonated with n-butyllithium and the resulting acetylides were quenched with iodine to provide iodoalkynes 3. 6 The iodoalkynes were reduced with diimide to provide iodoalkenes of type 4 with excellent control of olefin geometry. 6 A problem that always accompanied this step was reduction of 4 to the corresponding iodoalkane. Thus, these reactions were usually run to partial completion. The mixture of products and starting material was treated with aqueous trimethylamine to convert the alkane to a quarternary ammonium salt that was easily separated from the mixture of iodoalkene and starting iodoalkyne. 6 The starting material and iodoalkene 4 were then separated by column chromatography over silica gel. Esterification of the appropriate unsaturated acids 5 with solketal provided the alkenes 6 needed for the Suzuki coupling (Scheme 2). Scheme 1 Scheme 2 Figure 1Downloaded by: National University of Singapore. Copyrighted material.

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