Synthesis of endo-(3-azabicyclo[3.1.0]hex-6-yl)-methanol and derivatives as new geometric/charge mimics of glycosyltransfer transition states

The syntheses of azabicyclo[3.1.0]hexane transition state (TS) analogs are described. Cyclopropanation of N-Boc-3-pyrroline with ethyl diazoacetate afforded a 1.6:1 exo/endo ratio of the resulting ester. Reduction of the endo-isomer with LiAlH₄ yielded the alcohol which was phosphorylated, or iodinated to provide access to aglycon containing TS analogs.     

Synthesis of a novel tricyclic 4-quinolone. Incorporation of a spiro-cyclopropyl group at N1 by bridging to C2

An important pharmacophore in many quinolone antiinfectives is the N1 cyclopropane. By incorporating the cyclopropane into a N1 to C2 bridge, the first quinolone substrate incorporating a spiro fused cyclopropane, 8,9,10-trifluoro-2,3,4,6-tetrahydro-6-oxospiro[1H-benzo[c]quinolizine-1,l-cyclopropane]-5-carboxylic acid, ethyl ester ( 8 ), was prepared.     

Thioalkylated tetraethylene glycol: a new ligand for water soluble monolayer protected gold clusters

Ligand-stabilised, water-soluble gold nanoparticles of two different size ranges (2-4 and 5-8 nm) are readily prepared using monohydroxy (1-mercaptoundec-11-yl) tetraethylene glycol as a novel capping agent. These nanoparticles are as stable as alkylthiol-capped monolayer protected clusters (MPCs) and do not aggregate from aqueous solution under a wide range of stringent conditions. It is expected that this new material will be useful for a number of bio-analytical applications.     

A convenient stereoselective synthesis of cationic (η3-allyl)iron tetracarbonyl complexes

Allylic alcohols have been found to react with Fe₂(CO)₉ in ether to afford after addition of HBF₄/acetic anhydride, the corresponding (η³-allyl)Fe(CO)₄⁺BF₄^?- species (I) in moderate to good yields. The geometry of the starting alcohol is retained in the product complex; thus E-crotyl and -cinnamyl alcohols led to anti-substituted complexes, whereas the corresponding Z-alcohols produced syn-complexes.     

The important role of crystallinity and amylose ratio in thermal stability of starches

Journal of Thermal Analysis and Calorimetry - The thermal features of potato, banana, corn and cassava starches were correlated with structural properties. These starches were characterized by SEM,...     

Electronic properties of the trimethylenemethaneiron tricarbonyl group

The substituent electronic effects of trimethylenemethaneiron tricarbonyl [TMMFe(CO)₃] have been studied, with σ values reported. Determination of these values was accomplished through three different techniques: a study of acidity relative to benzoic acid with TMMFe(CO)₃ acting as a substituent of benzoic acid; ¹⁹F-nuclear magnetic resonance (NMR) shielding analysis of m-fluorophenylTMMFe(CO)₃; and ¹³C-NMR shielding analysis of phenylTMMFe(CO)₃. The TMMFe(CO)₃ group behaves in much the same manner as a phenyl group (i.e. weakly electron releasing by resonance and weakly electron attracting by induction). The syntheses of the substituted phenyltrimethyleneiron tricarbonyl compounds are described.     

Development of nonproprietary phosphine ligands for the Pd-catalyzed amination reaction

A new family of pyrazole and bi-pyrazole phosphine ligands are reported that perform efficiently in the Pd-catalyzed amination reaction. Of the ligands screened, ligand 1 emerged as the most compatible for couplings involving both primary and secondary amines with typical yields of 84-99%.