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C 18 H 22 FeO 7 cristallise dans P2 1 2 1 2 1 avec a=6,4633, b=10,7995, c=28,056 A, Z=4; affinement jusqu'a R=0,030. Une caracteristique surprenante de la structure moleculaire est une orientation non usuelle: cis «anti-sterique» des coordinats menthyloxy et Fe(CO) 4 . Les resultats experimentaux sont completes par les resultas de calculs ab initio

A new and efficient synthetis of 1,6-dioxaspiro[4,4]nonane-spiroacetals, starting from the simple building blocks acetone and oxiranes is described.

Using intestinal sleeves in vitro, we studied the effect of dietary carbohydrate on active monosaccharide uptake in mice. Dietary carbohydrate did not affect numerous parameters of intestinal structure, such as length, circumference, weight, protein content, villus dimensions and density, and area at the villus level. Mice on a carbohydrate-free diet had active D-glucose uptake relatively independent of position along the small intestine. A carbohydrate-containing diet reversibly and within 1 day stimulated uptake except in the ileum, restoring the proximal-to-distal gradient in glucose uptake normally observed. This stimulation involved a 81-116% increase in the Michaelis- Menton constant Vmax, and also an apparent increase in the Michaelis- Menton constant Km, that may however be an artifact arising from unstirred-layer effects. Active uptake of 3-O-methyl-D-glucose also increased, permeability to glucose remained unchanged, and proline uptake reversibly decreased (probably due to the lower protein content of the carbohydrate-containing diets). The effect of fasting on active monosaccharide uptake seemed largely due to withdrawal of dietary carbohydrate, rather than of calories per se. It is concluded that dietary carbohydrate causes induction of monosaccharide carriers in the intestine, along with its more familiar induction of pancreatic amylase and intestinal disaccharidases. Substrate-dependent carrier induction may be physiologically significant in maintaining the proximal-to-distal gradient of glucose transport. An appendix presents measurements of villus area as a function of position along the intestine.

Highly enantioselective α-alkylations of ketones and aldehydes using metalated chiral hydrazones of (S)- or (R)-1-amino-2-methoxymethyl-pyrrolidine (“SAMP/RAMP-hydrazones”) are described. Furthermore, reduction/N-N bond cleavage of SAMP-hydrazones leads to primary amines of (R)- or (S)-configuration with selectivities of up to 94% ee depending on the reducing agent. Proline derived chiral hydrazines can also be used efficiently as agents for chromatographic (HPLC) resolution of aldehydes. Lithiated chiral (thio)formamides and allylamines are used in asymmetric nucleophilic acylation processes and as chiral homoenolate equivalents, respectively. In addition, new simple and generally applicable syntheses of spiroacetals and α-aminoketones are presented.

Dimethylhydrazone von enolisierbaren Aldehyden oder Ketonen, z.B. (I), konnen quantitativ in α-Stellung unter Bildung von hochreaktiven Li-Derivaten, z.B. (II), metalliert werden.

Hybrid silicon focal plane arrays for infrared detection have progressed rapidly over the past year from the point of proof of concept to pilot production. Packaging schemes have been developed which will allow the integration of thousands of pixels into a large area, two-dimensional focal plane. The performance of silicon focal planes has been optimized and producibility aspects addressed. This paper discusses operating characteristics and packaging concepts of hybrid silicon focal planes and investigates their future applications.

On decrit la synthese enantioselective d'α-hydroxycetones par additions nucleophiles sur des aldehydes, d'equivalents d'anions acyl chiraux obtenus par metallation d'α-aminonitriles