Conversion of carbamates to amidosulfones and amides. Synthesis of the [14C]-labeled antiobesity agent Ro23-7637

[reaction: see text] Carbamates of primary and secondary amines react with the dianion of methyl phenyl sulfone to yield amidosulfones. Alylation of the amidosulfone followed by reductive removal of the sulfonyl residue gives an amide.     

Variable strategy toward carbasugars and relatives. 4. Viable access to (4a-carbapentofuranosyl)amines, (5a-carbahexopyranosyl)amines,and amino acids thereof

A chiral, divergent synthesis of two carbafuranosylamines, 1 and 2, two carbapyranosylamines, 3 and 4, two carbafuranosylamino acids, 5 and 6, and two carbapyranosylamino acids, 7 and 8, has been achieved. Highlights of the procedure include the following: a diastereoselective crossed vinylogous Mukaiyama aldol coupling between N-(tert-butoxycarbonyl)-2-[(tert-butyldimethylsilyl)oxy]pyrrole (TBSOP, 9) and 2,3-O-isopropylidene-D-glyceraldehyde (10) for the assembly of the target compound carbon backbone; a high-yielding silylative cycloaldolization that gives the cyclopentanoid and cyclohexanoid motifs; and a reductive or hydrolytic breakage of the lactam C(O)-N link to liberate the carbasugar and install the desired pseudo-anomeric amine and the hydroxymethyl or carboxyl functionalities. The sequences leading to trans-configured carbafuranosyl compounds 1 and 5 and carbapyranosyl compounds 3 and 7 were 12- and 13-step processes, with overall yields of 34%, 35%, 17%, and 16%. Cis-configured isomers 2, 4, 6, and 8 were obtained only in minor yields.     

The Assisi Chartula by the hand of Saint Francis: non-destructive characterization by spectroscopic spectrometric and optical methods

Just two examples of writings by the hand of S. Francesco are known to exist: a letter to Brother Leone, kept in the archives of Spoleto cathedral and the Chartula, displayed in the Hall of Reliquaries at Assisi's Sacro Convento. For the first time in its history the Chartula has undergone a series of non-destructive analyses, with the object of establishing its current state of conservation and the types of inks used in its making. A new display case has been designed and built for the improved conservation of this precious document. The new housing substitutes an ancient case, which was located inside the original reliquary.     

A General Scheme for Shape Preserving Planar Interpolating Curves

This paper describes the application of the so-called Abstract Schemes (AS) for the construction of shape preserving interpolating planar curves. The basic idea behind AS is given by observing that when we interpolate some data points by a spline, we can dispose of several free parameters d ₀,d ₁,...,d _N (d _i R ^q ), which are associated with the knots. If we now express shape constraints as conditions relative to each interval between two knots, they can be rewritten as a sequences of inclusion conditions: ({d} _i ,d _i+1)D _i R ^2q , where the sets D _i are the corresponding feasible domains. In this setting the problems of existence, construction and selection of an optimal solution can be studied with the help of Set Theory in a general way. The method is then applied for the construction of shape preserving, planar interpolating curves.     

Permeabilities and stabilities of large dihexadecylphosphate and dioctadecyldimethylammonium chloride vesicles

Sodium dihexadecylphosphate (DHP) vesicles, with a mean external diameter of 0.27 μm, were obtained by chloroform vaporization followed by gel filtration. The relative volume of the internal aqueous compartment, estimated measuring entrapment of [¹⁴C] sucrose, was 13 liters/mol. DHP and dioctadecyldimethyl ammonium chloride (DODAC) large vesicles were stable up to 20 days at room temperature. In contrast, small sonicated DHP and DODAC vesicles were stable for some hours after preparation. Both DHP and DODAC large vesicles were impermeable toward most solutes tested. Large DHP vesicles responded as ideal osmometers toward gradients of sucrose, NaCl, or NaOH. The behavior of large vesicles of synthetic amphiphiles and of phospholipids was found to be analogous in the gel state.