Treatment of the heterobimetallic iron(II) alkoxides [(THF)MFe(OtBu)(3)](2) with p-tert-butylcalix[4]areneH(4) (L(1)H(4)) affords the oxo-bridged diiron(III) complexes {Fe[M(NCMe)(x)](2)L(1)}(2)(mu-O), M = Na, x = 2 1 x 8(CH(3)CN), M = K, x = 3 2 x 3.5(CH(3)CN); similar use of p-tert-butylcalix[6]areneH(6) (L(2)H(6)) afforded [{Fe(2)(mu-O)Na(2)(OH(2))(NCMe)(2)L(2)}(2)][{Fe(2)(mu-O)Na(OH(2))(NCMe)(6)L(2)}(2)](2-)[Na(NCMe)(5)](2)(2+) 3 x 9.46(CH(3)CN) and [{Fe(2)(mu-O)L(2)(K(NCMe)(2))(2)}(2)] 4 x 10.8(MeCN), respectively. In the case of 4, a minor product {(L(2)(2)Fe(8)O(8))[K(NCMe)(1.5)K(H(2)O)(NCMe)(2.5)](2)} 5 x 6(CH(3)CN), which is comprised of chains of (L(2)(2)Fe(8)O(8)) clusters bridged by K/MeCN fragments, is also isolated. Use of p-tert-butylcalix[8]areneH(8) (L(3)H(8)) and two equivalents of [(THF)KFe(OtBu)(3)](2) affords [(K(2)(mu-NCCH(3))(4)(mu-OH(2)))(2)(Fe(2)(mu-O)L(3)H(2))(2)(CH(3)CN)(2)] 6 x 9(CH(3)CN). In the case of p-tert-butyltetrahomodioxacalix[6]areneH(6) (L(4)H(6)), reaction with [(THF)MFe(OtBu)(3)](2) (two equivalents) leads to isolation of the pseudoisomorphic complexes [M(2)(CH(3)CN)(4)L(4)Fe(2)(mu-O)] x 4 CH(3)CN M = Na 7 x 4(CH(3)CN), M = K 8 x 2(CH(3)CN); similar use of p-tert-butylhexahomotrioxacalix[3]areneH(3) (L(5)H(3)) led to [Na(2)Fe(2)(mu-OH)(2)(L(5))(2)(CH(3)CN)(4)] 9 x 2(CH(2)Cl(2)). The complex [L(4)(ZnEt)(4)Zn(2)(CH(3)CN)(4)(mu-OEt)(2)], 10 x 2(CH(3)CN), isolated from the reaction of L(4)H(6) and ZnEt(2) is also reported. Complexes 1-10 are structurally characterized (partially in the case of 4) and screened (not 5) as catalysts for the ring opening polymerization of epsilon-caprolactone.

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To become independent of petroleum resources, societies have to develop methods to synthesize full-biobased polymers from natural products directly. In this study, full-biobased cellulose esters were synthesized by the oxidative esterification process between cellulose and natural α,β-unsaturated aldehydes in an ionic liquid working as solvent and catalyst. The role of the ionic liquid in this cellulose-modification system was systematically investigated, and a newly designed noncarboxylate-type ionic liquid, 1-ethyl-3-methylimidazolium 2-pyridinolate (EmimOPy), was developed to prevent a serious side reaction in which the carboxylate anion of the carboxylate-type ionic liquid is introduced into the hydroxyl group of cellulose as an ester group on the products. Under optimized conditions, this oxidative esterification-reaction system in EmimOPy afforded fully substituted cellulose ester (up to the degree of substitution = 3.0). Furthermore, cellulose reacted with several types of aldehyde substrates, even biobased low-reactive α- or β-substituted unsaturated aldehydes (e.g., citral and perillaldehyde). Thus, this synthesis demonstrates excellent atom economy without using any additional catalysts or activators under metal-free conditions.

A series of boronic acid-containing saccharide receptors was synthesised via copper catalysed azidealkyne cycloaddition (CuAAC) reactions. Their saccharide binding capacity was studied by 1 H and 11 B NMR spectroscopy titrations and isothermal titration calorimetry (ITC) techniques. Fluorescent sensors were generated by linking a phenylboronic acid (PBA) receptor with fluorophores via a triazole-linker. Fluorescence titrations with fructose revealed that the substitution pattern about the PBA influences the fluorescence response to saccharides. Titrations studied by 1 H NMR spectroscopy suggested that fructose binding is enhanced when the aromatic ring bearing the boronic acid has the triazole-containing substituent at the ortho position. No evidence of either a dative N-B bond or solvent insertion (between B and N) was observed by 11 B NMR spectroscopy. These results demonstrate that synthetic accessible triazole receptors may allow rapid sensor synthesis, screening and discovery. † Electronic supplementary information (ESI) available. CCDC 1475996 and 1475987. For ESI and crystallographic data in CIF or other electronic format see

A series of single enantiomer, 2,4-cis-disubstituted amino azetidines were synthesised and used as ligands for copper-catalysed Henry reactions of aldehydes with nitromethane. Optimisation of ligand substituents and the reaction conditions was conducted. The enantiomeric excess of the formed products was highest when alkyl aldehydes were employed in the reaction (>99% e.e.). The absolute stereochemistry of one representative azetidine derivative salt was determined by analysis of the Flack parameter of an XRD single crystal structure. The origin of selectivity in catalysis was investigated computationally, revealing the importance of the amino-substituent in determining the stereochemical outcome. A racemic platinum complex of a cis-disubstituted azetidine is examined by XRD single crystal structure analysis with reference to its steric parameters, and analogies to the computationally determined copper complex catalyst are drawn. A preliminary example of the use of a cis-disubstituted azetidine scaffold in thiourea H-bonding catalyst is noted in the supporting information.