Extremely high regio- and stereoselective C-C bond formation of substituted γ-hydroxylactams: synthesis of macronecines based on their structural duality

With a view to develop a new synthetic entry for the necine bases, treatment of functionalized γ-hydroxylactams was found to undergo quite high regio- and diastereoselective carbon-carbon bond formation reactions, affording the corresponding structurally dualistic alkylated lactams in satisfactory yields. The reaction was further applied to the practical and efficient synthesis of (±)-macronecine [(1S^∗,2R^∗,7aR^∗)-1-hydroxymethyl-2-hydroxypyrrolizidine] and (±)-2-epi-macronecine [(1S^∗,2S^∗,7aR^∗)-1-hydroxymethyl-2-hydroxypyrrolizidine].     

Aldol-type reaction of a 4-pyrone: a straightforward approach to 4-pyrone-containing natural products

A straightforward approach to 4-pyrone-containing natural products has been developed, which includes an aldol-type reaction between 2,6-diethyl-3,5-dimethyl-4-pyrone and aldehydes. The counter cation of the carbanion of the pyrone was found to play an important role in this reaction.     

New asymmetric strategy for the total synthesis of naturally occurring (+)-alexine and (−)-7-epi-alexine

A novel and highly convenient process is described for the asymmetric synthesis of polyhydroxylated pyrrolizidine alkaloids, (+)-alexine [(1R,2R,3R,7S,7aS)-3-hydroxymethyl-1,2,7-trihydroxypyrrolizidine] and (−)-7-epi-alexine [(1R,2R,3R,7R,7aS)-3-hydroxymethyl-1,2,7-trihydroxypyrrolizidine], as the potent glycosidase inhibitors by featuring the efficient and stereodefined elaboration of the functionalized pyrrolidine derivatives, which were, in turn, prepared via stereoselective manipulation of the homochiral allyl alcohol precursors derived from l-xylose.     

Total synthesis of the proposed structures of hyacinthacines C2, C3, and their C5-epimers

Synthesis and structural confirmation of highly oxygenated pyrrolizidine alkaloids, hyacinthacines C₂ [(1S,2R,3R,5R,7S,7aR)-3,5-hydroxymethyl-1,2,7-trihydroxypyrrolizidine], C₃[(1S,2R,3R,5S,7R,7aR)-3,5-hydroxymethyl-1,2,7-trihydroxypyrrolizidine], and their C5-epimers were achieved on the basis of the highly divergent method employing (S)-(−)-2-pyrrolidone-5-carboxylic acid as the starting material.     

Spontaneous formation of dye-functionalized gold nanoparticles using reverse micellar systems

Detailed exploratory and mechanistic investigations on spontaneous formation of dye-functionalized gold nanoparticles (GNPs) using dye-based reverse micellar systems are described in this publication. The accumulated results from spectroscopic and microscopic investigations demonstrated that water molecules confined within nanoscopic enclosure of the self-assembled reverse micelles played critical role in the redox processes of aurate ions to produce GNPs, which are assumed to have approximately constant size distributions. The resulting dye-functionalized GNPs were found to offer their absorption and fluorescence emission tunability by changing the medium polarity as well as to exhibit excellent film-forming properties to give optically homogeneous polystyrene thin films. These key findings in addition to broad applicability of the self-assembling process with a variety of dye analogues have led to a conclusion that the protocol presented here serves as a versatile synthetic method to provide a potential convenience for future development of new organic-inorganic hybrid nanomaterials.     

Three-dimensional magnetic resonance imaging after ultrasonography for assessment of fetal gastroschisis

A 24-year-old woman (Gravida I, Para I) at estimated 32 weeks of pregnancy was referred to our department for evaluation of a suspected fetal gastroschisis. Ultrasound scan revealed multiple loops of dilated bowel outside the fetal abdomen and absence of membrane surrounding the herniated loops of the intestines. Three-dimensional (3D) magnetic resonance imaging was performed to obtain more information on the bowel both outside and inside the abdomen. Images were constructed with T1-weighted fat-suppressed 3D fast low-angle shot sequences using a maximum intensity projection algorithm. The 3D images made possible the realization of fetal bowel conditions with greater definition and accuracy.     

Synthesis and spectral properties of perylene–rhodamine dyads with lipophilic dendritic auxiliaries

The present publication reports a new entry of perylene–rhodamine dyads, whose solubilities in organic solvents are enhanced by the lipophilic dendritic auxiliaries. Spectroscopic studies on these dyad systems have demonstrated that the intramolecular Förster resonance energy transfer (FRET) from the perylene donor to the rhodamine acceptor was activated upon protonation with either H₂SO₄ or TFA to result in drastic colour change of the fluorescence emissions. This phenomenon can be reasonably accounted for in terms of the switching behaviour of the FRET interactions, which is suppressed by disruptive interference from lone pair electrons of the amino moieties.