Yasufumi Ohfune

Structure Determination of a New Juvenile Hormone from a Heteropteran Insect

The structure of the juvenile hormone (JH) in the suborder Heteroptera, order Hemiptera, has been known for a very long time to be different from the JH of other orders, but the structure has been a matter of controversy. The structure was first elucidated by an unprecedented approach involving the screening of a JH molecular library. The novel Heteroptera-specific JH (JHSB3) is a new category of JH that is featured by the skipped bisepoxide structure.

Total synthesis of (-)-amathaspiramide F.

The stereoselective total synthesis of the marine alkaloid (-)-amathaspiramide F (1) was achieved from the alpha-hydoxy-alpha-ethynylsilane 2. The crucial steps in this synthesis involved not only the enolate Claisen rearrangement of the alpha-acyloxy-alpha-alkenylsilane 6 for the construction of the nitrogen-containing quaternary carbon center, but also the chemoselective formation of the azaspirohemiaminal 12 using heptamethyldisilazane as the methylamine equivalent and the regioselective dibromination of the phenol moiety of 12 using n-Bu(4)NBrCl(2).

Efficient Total Synthesis of (−)-Kaitocephalin†

A highly diastereoselective total synthesis of (-)-kaitocephalin, a novel antagonist of ionotropic glutamate receptors, was accomplished in 12 steps starting from 5-substituted proline ester via the aldol reaction with OBO-serine aldehyde, (E)-selective alpha,beta-dehydroamino acid synthesis using a new HWE reagent, and catalytic hydrogenation.

Biological activities of juvenile hormone III skipped bisepoxide in last instar nymphs and adults of a stink bug, Plautia stali

Juvenile hormone III skipped bisepoxide (JHSB(3)), methyl (2R,3S,10R)-2,3;10,11-bisepoxyfarnesoate was recently determined as a novel juvenile hormone (JH) in a stink bug, Plautia stali. To further confirm the biological function of JHSB(3) in this insect, its juvenilizing, reproduction-stimulating and diapause-terminating activities and the presence in the hemolymph were examined. Topical application of JHSB(3) to last instar nymphs inhibited their metamorphosis in a dose-dependent fashion. In allatectomized and diapausing adults, JHSB(3) application exerted stimulatory effects on the development of ovaries and ectadenia in females and males, respectively. JHSB(3) was detected from the hemolymph of reproductively active females by gas chromatography-mass spectrometry analysis while its titer in the hemolymph collected from diapausing adults was too low to be detected. These results demonstrated that JHSB(3) has biological function as a JH in P. stali. Topical application of JHSB(3), its stereoisomers and 10R-JH III also indicated that compounds with the 2R,3S-configuration were more potent than those with the 2S,3R-configuration and 2,3-double bond.

Short Total Synthesis of (−)-Kainic Acid

A short total synthesis of (-)-kainic acid has been developed involving a novel diastereofacial differentiating Cu-catalyzed Michael addition-cyclization reaction, which provided access to a chiral pyrroline in a highly stereoselective manner. The chiral pyrroline was converted to (-)-kainic acid via the stereoselective 1,4-reduction of the pyrroline double bond in three steps.

Efficient synthesis of optically active α-substituted glutamate analogs possessing α-hydroxymethyl and α-alkoxymethyl groups

Highly enantioselective synthesis of (2R)-α-(hydroxymethyl)glutamate (1), a selective agonist of mGluR2 and 3, was achieved in short steps using an asymmetric version of the Strecker synthesis. This was converted into its α-methoxymethyl- and α-benzyloxymethyl derivatives 2 and 3, possible ligands as tools to investigate glutamate receptors, via protection of the sterically hindered amino group by means of phase transfer catalyst.

Stereocontrolled synthesis of a potent agonist of group II metabotropic glutamate receptors, (+)-LY354740, and its related derivatives

Abstract Efficient synthesis of (+)-2-aminobicyclo[3.1.0]hexane-2,6-dicarboxylic acid (LY354740: 1 ) and its structurally related analogs (−)- 2 and (−)- 3 has been accomplished starting with (1 S ,2 R )-1-amino-2-hydroxycyclopentane- or cyclohexanecarboxylic acid ( 4 or 17 ) via an intramolecular cyclopropanation of α-diazo acetamide.

Solid phase synthesis of α-amino squaric acid-containing peptides

A new method has been developed for the synthesis of 3-(1-aminoalkyl)-4-hydroxycyclobut-3-ene-1,2-dione [α-amino squaric acid (α-Asq)]-containing peptides using solid phase peptide synthesis according to an Fmoc protecting group strategy. FmocHN-Gly-[α-Asq]-Oi-Pr was successfully used as a coupling unit in this method, which allowed for the construction of α-Asq-containing hexapeptide libraries including Sq-Gly and Sq-Phe units using the Wang-resin. Peptides containing the α-Asq moiety exhibited inhibitory activity towards a digestive enzyme.