Relationships between chiroptical properties (Optical Rotatory Dispersion, ORD, and Circular Dichroism, CD) and Conformation of structur— ally simple isotactic polymers and copolymers derived from optically active monomers are reviewed. Both experimental and calculated values fit with chain cotiformations consisting prëdomirantly of one screw sense helical sections due to dissyinmetric cooperat...

By use of an asymmetric Ullmann coupling involving chiral naphthalene oxazolines 1, the title compounds were prepared in good yields and with high diastereoselectivity. Hydrolysis of the binaphthyl oxazolines 2 led to the di-aldehydes 5, which were transformed into the azepine derivative, 6. The latter was treated with the appropriate phosphoryl halide to access the chiral HMPA systems 7 and 9....

An all-trans-retinal (ATR) dimer (1) isolated from photoreceptor outer segments was found to have a stereogenic center at C13' flanked by tetraene (295 nm) and hexaenal (438 nm) chromophores. Analytical chiral HPLC (Chiralcel OD) revealed that the isolated retinoid had formed in 13% enantiomeric excess. Using a combination of (1)H-(1)H NOESY constraints, molecular modeling, and CD exciton coupl...

The absolute configuration of gymnocin-B has been determined to be (S)-10 and (S)-37. Three challenges toward the configurational assignment of this largest of the polyether marine toxin include (i) introduction of p-(meso-triphenylporphyrin)-cinnamate group (TPPcinnamate) on sterically hindered 10-, 37-hydroxyls under mild conditions, (ii) conformational analysis in the presence of TPPcinnamat...

Chromic acid oxidation of manumycin (1), an antibiotic produced by Streptomyces parvulus (strain Tü 64), led to the isolation of 2-(2-methyl-4-oxo-2-pentenoylamino)-5,6-epoxy-1,4-benzoquinone (3) and (-)-(R)-2-methylhexanoic acid (4). From the absolute configuration of 4, determined by comparing its optical rotation with published data, follows the absolute configuration at the center of chiral...

Since the first description of epipubic bones in 1698, their functions and those of the associated abdominal muscles of monotremes and marsupial mammals have remained unresolved. We show that each epipubic bone is part of a kinetic linkage extending from the femur, by way of the pectineus muscle, to the epipubic bone, through the pyramidalis and rectus abdominis muscles on one side of the abdom...

We propose a new couplet of identity and view manifolds for multi-view shape modeling that is applied to automated target tracking and recognition (ATR). The identity manifold captures both inter-class and intra-class variability of target shapes, while a hemispherical view manifold is involved to account for the variability of viewpoints. Combining these two manifolds via a non-linear tensor d...

A combined chemical/chiroptical microscale protocol for the determination of absolute configurations of cyclic alpha-hydroxyketones is described. The hydroxyl group in cyclic alpha-hydroxyketones is converted into (3-aminopropylamino)acetate (NH2CH2CH2CH2NHCH2COOR), or more generally, according to a newly developed protocol, into (3-hydroxypropylamino)acetate group (HOCH2CH2CH2NHCH2COOR). The r...

The genus Albistyla is described for a group of similar, highly distinctive Neotropical species that key out at couplet 55 of the key to Neotropical Sphaeroceridae in Marshall and Buck (2010). Albistyla is diagnosed by the combination of a single pair of strongly cruciate interfrontal bristles, two dorsocentral bristles, and the costa ending at the tip of R4+5. It is defined as a monophyletic g...