Asymmetric synthesis of (-)-dehydro-exo-brevicomin with a photoisomerisation-intramolecular acetalisation sequence.

We herein report a novel, short asymmetric synthesis of (-)-dehydro-exo-brevicomin (DHB, 1), a sex pheromone isolated from house mice, in 44% overall yield, the highest yield reported so far, over eight steps from trans-3-hexen-1-ol (7). We successfully prepared the target molecule (-)-1 from spontaneous intramolecular acetalisation after the photoisomerisation of trans-enone 6, which generated the corresponding cis-enone 5in situ, the possible biosynthetic precursor of DHB.

Biomimetic systems involving sequential redox reactions in glycolysis - the sulfur effect.

Magnesium hemithioacetates were used as model cysteine compounds to mimic natural hemithioacetals, and their biomimetic oxidation reactions using a model NAD+ compound were investigated. Cyclic hemithioacetate was found to be the best substrate for the reaction with the model NAD+ compound, which gave the corresponding NADH analog in excellent yield.

Elucidation of Racemization Process of Azaspirene Skeleton in Neutral Aqueous Media.

Azaspirene and related congeners, which possess various biological activities, have a unique spirocyclic core structure. However, there are few studies on the chemical properties of (-)-azaspirene, despite the fact that it may provide important insights into unveiling the biosynthetic pathway. Here, we report a nine-step chemical synthesis of an azaspirene analogue with a new finding that the natural (-)-azaspirene skeleton easily racemizes in neutral aqueous media.

Azaspirene analogs inhibit the growth of human uterine carcinosarcoma in vitro and in vivo.

Uterine carcinosarcoma is a highly aggressive gynecological neoplasm that responds poorly to conventional chemotherapy and radiotherapy. Recent studies have shown high angiogenic activities of this tumor, hence anti-angiogenic approaches are expected to provide new treatment strategies for this tumor. In previous work, azaspirene was isolated from Neosartorya sp. fungi, and in vitro anti-angiogenic activities were shown. In the present study, the anti-angiogenic effects of azaspirene analogs, synthetic molecules with a shorter ethyl group replacing a hexadienyl side-chain of the natural compound, were assessed in vitro using human umbilical vein endothelial cells (HUVECs) co-cultured with FU-MMT-3 human uterine carcinosarcoma cells. The anti-tumor and anti-angiogenic effects of these analogs were also evaluated in vivo using FU-MMT-3 xenografted tumors in nude mice. The azaspirene analogs inhibited the tube formation of HUVECs induced by FU-MMT-3 cells in vitro and significantly suppressed tumor growth in vivo compared to the untreated group (control). A significant reduction of the microvessel density in tumors was observed, in comparison to the control. No apparent toxicity, including body loss, was observed in any mice treated in this study. These azaspirene analogs may be effective against uterine carcinosarcoma, possibly acting via potent anti-angiogenic effects.

Genetic dissection of pheromone processing reveals main olfactory system-mediated social behaviors in mice.

Most mammals have two major olfactory subsystems: the main olfactory system (MOS) and vomeronasal system (VNS). It is now widely accepted that the range of pheromones that control social behaviors are processed by both the VNS and the MOS. However, the functional contributions of each subsystem in social behavior remain unclear. To genetically dissociate the MOS and VNS functions, we established two conditional knockout mouse lines that led to either loss-of-function in the entire MOS or in the dorsal MOS. Mice with whole-MOS loss-of-function displayed severe defects in active sniffing and poor survival through the neonatal period. In contrast, when loss-of-function was confined to the dorsal MOB, sniffing behavior, pheromone recognition, and VNS activity were maintained. However, defects in a wide spectrum of social behaviors were observed: attraction to female urine and the accompanying ultrasonic vocalizations, chemoinvestigatory preference, aggression, maternal behaviors, and risk-assessment behaviors in response to an alarm pheromone. Functional dissociation of pheromone detection and pheromonal induction of behaviors showed the anterior olfactory nucleus (AON)-regulated social behaviors downstream from the MOS. Lesion analysis and neural activation mapping showed pheromonal activation in multiple amygdaloid and hypothalamic nuclei, important regions for the expression of social behavior, was dependent on MOS and AON functions. Identification of the MOS-AON-mediated pheromone pathway may provide insights into pheromone signaling in animals that do not possess a functional VNS, including humans.

Planar-to-planar chirality transfer in the excited state. Enantiodifferentiating photoisomerization of cyclooctenes sensitized by planar-chiral paracyclophane.

Photochemical planar-to-planar chirality transfer was effected by using (R)-[10]paracyclophane-12-carboxylates as a planar-chiral sensitizer and (Z)-cyclooctene and (Z,Z)-1,5-cyclooctadiene as prochiral substrates to give a planar-chiral (E)- and (E,Z)-isomer in up to 44% and 87% enantiomeric excess, respectively, the latter of which being the highest ever reported for a sensitized photochirogenic reaction.

Synthesis and structural revision of phomopsin B, a novel polyketide carrying a 10-membered cyclic-ether ring.

Total synthesis of the proposed structure 2 for phomopsin B was achieved by using an intramolecular olefin metathesis as a key step. The spectral data, however, did not match with those of the natural product reported. Re-examination of the reported NMR data led to the structural revision of phomopsin B to known dothiorelone A 18. The R configuration of dothiorelone A was determined by total synthesis through a cross-metathesis with a chiral olefin 19.

Synthesis of planar-chiral paracyclophanes via samarium(II)-catalyzed intramolecular pinacol coupling.

[reaction: see text] A series of [n]paracyclophanediols (n = 8-12) was synthesized by samarium-catalyzed pinacol coupling for their ansa-bridge formation. Enantiomerically pure [n]paracyclophane esters were derived from the diols in a several steps via chiral resolution (for n = 10) or via crystallization-induced asymmetric transformation (for n = 11) by using amino alcohol auxiliaries and their selective cleavages.

Biomimetic Oxidation of Aldehyde with NAD+ Models: Glycolysis-Type Hydrogen Transfer in an NAD+ /NADH Model System.

Just like in biological systems, the GAPDH-catalyzed oxidation of aldehyde to carboxylate proceeds in conjunction with 1,4-selective reduction of NAD+ to NADH model compounds [Eq. (1)]. The combination of GAPDH- and LDH-type transfer reactions is also described here as a system mimic for the NAD+ /NADH redox cycle in anaerobic glycolysis. GAPDH=D-glyceraldehyde-3-phosphate dehydrogenase, LDH=L-lactate dehydrogenase.